JDK 11 java.base.jmod - Base Module
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⏎ java/lang/ClassLoader.java
/*
* Copyright (c) 2013, 2018, Oracle and/or its affiliates. All rights reserved.
* ORACLE PROPRIETARY/CONFIDENTIAL. Use is subject to license terms.
*
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package java.lang;
import java.io.InputStream;
import java.io.IOException;
import java.io.UncheckedIOException;
import java.io.File;
import java.lang.reflect.Constructor;
import java.lang.reflect.InvocationTargetException;
import java.net.URL;
import java.security.AccessController;
import java.security.AccessControlContext;
import java.security.CodeSource;
import java.security.PrivilegedAction;
import java.security.ProtectionDomain;
import java.security.cert.Certificate;
import java.util.ArrayDeque;
import java.util.Arrays;
import java.util.Collections;
import java.util.Deque;
import java.util.Enumeration;
import java.util.HashMap;
import java.util.HashSet;
import java.util.Hashtable;
import java.util.Map;
import java.util.NoSuchElementException;
import java.util.Objects;
import java.util.Set;
import java.util.Spliterator;
import java.util.Spliterators;
import java.util.Vector;
import java.util.WeakHashMap;
import java.util.concurrent.ConcurrentHashMap;
import java.util.function.Supplier;
import java.util.stream.Stream;
import java.util.stream.StreamSupport;
import jdk.internal.loader.BuiltinClassLoader;
import jdk.internal.perf.PerfCounter;
import jdk.internal.loader.BootLoader;
import jdk.internal.loader.ClassLoaders;
import jdk.internal.misc.Unsafe;
import jdk.internal.misc.VM;
import jdk.internal.ref.CleanerFactory;
import jdk.internal.reflect.CallerSensitive;
import jdk.internal.reflect.Reflection;
import sun.reflect.misc.ReflectUtil;
import sun.security.util.SecurityConstants;
/**
* A class loader is an object that is responsible for loading classes. The
* class {@code ClassLoader} is an abstract class. Given the <a
* href="#binary-name">binary name</a> of a class, a class loader should attempt to
* locate or generate data that constitutes a definition for the class. A
* typical strategy is to transform the name into a file name and then read a
* "class file" of that name from a file system.
*
* <p> Every {@link java.lang.Class Class} object contains a {@link
* Class#getClassLoader() reference} to the {@code ClassLoader} that defined
* it.
*
* <p> {@code Class} objects for array classes are not created by class
* loaders, but are created automatically as required by the Java runtime.
* The class loader for an array class, as returned by {@link
* Class#getClassLoader()} is the same as the class loader for its element
* type; if the element type is a primitive type, then the array class has no
* class loader.
*
* <p> Applications implement subclasses of {@code ClassLoader} in order to
* extend the manner in which the Java virtual machine dynamically loads
* classes.
*
* <p> Class loaders may typically be used by security managers to indicate
* security domains.
*
* <p> In addition to loading classes, a class loader is also responsible for
* locating resources. A resource is some data (a "{@code .class}" file,
* configuration data, or an image for example) that is identified with an
* abstract '/'-separated path name. Resources are typically packaged with an
* application or library so that they can be located by code in the
* application or library. In some cases, the resources are included so that
* they can be located by other libraries.
*
* <p> The {@code ClassLoader} class uses a delegation model to search for
* classes and resources. Each instance of {@code ClassLoader} has an
* associated parent class loader. When requested to find a class or
* resource, a {@code ClassLoader} instance will usually delegate the search
* for the class or resource to its parent class loader before attempting to
* find the class or resource itself.
*
* <p> Class loaders that support concurrent loading of classes are known as
* <em>{@linkplain #isRegisteredAsParallelCapable() parallel capable}</em> class
* loaders and are required to register themselves at their class initialization
* time by invoking the {@link
* #registerAsParallelCapable ClassLoader.registerAsParallelCapable}
* method. Note that the {@code ClassLoader} class is registered as parallel
* capable by default. However, its subclasses still need to register themselves
* if they are parallel capable.
* In environments in which the delegation model is not strictly
* hierarchical, class loaders need to be parallel capable, otherwise class
* loading can lead to deadlocks because the loader lock is held for the
* duration of the class loading process (see {@link #loadClass
* loadClass} methods).
*
* <h3> <a id="builtinLoaders">Run-time Built-in Class Loaders</a></h3>
*
* The Java run-time has the following built-in class loaders:
*
* <ul>
* <li><p>Bootstrap class loader.
* It is the virtual machine's built-in class loader, typically represented
* as {@code null}, and does not have a parent.</li>
* <li><p>{@linkplain #getPlatformClassLoader() Platform class loader}.
* All <em>platform classes</em> are visible to the platform class loader
* that can be used as the parent of a {@code ClassLoader} instance.
* Platform classes include Java SE platform APIs, their implementation
* classes and JDK-specific run-time classes that are defined by the
* platform class loader or its ancestors.
* <p> To allow for upgrading/overriding of modules defined to the platform
* class loader, and where upgraded modules read modules defined to class
* loaders other than the platform class loader and its ancestors, then
* the platform class loader may have to delegate to other class loaders,
* the application class loader for example.
* In other words, classes in named modules defined to class loaders
* other than the platform class loader and its ancestors may be visible
* to the platform class loader. </li>
* <li><p>{@linkplain #getSystemClassLoader() System class loader}.
* It is also known as <em>application class loader</em> and is distinct
* from the platform class loader.
* The system class loader is typically used to define classes on the
* application class path, module path, and JDK-specific tools.
* The platform class loader is a parent or an ancestor of the system class
* loader that all platform classes are visible to it.</li>
* </ul>
*
* <p> Normally, the Java virtual machine loads classes from the local file
* system in a platform-dependent manner.
* However, some classes may not originate from a file; they may originate
* from other sources, such as the network, or they could be constructed by an
* application. The method {@link #defineClass(String, byte[], int, int)
* defineClass} converts an array of bytes into an instance of class
* {@code Class}. Instances of this newly defined class can be created using
* {@link Class#newInstance Class.newInstance}.
*
* <p> The methods and constructors of objects created by a class loader may
* reference other classes. To determine the class(es) referred to, the Java
* virtual machine invokes the {@link #loadClass loadClass} method of
* the class loader that originally created the class.
*
* <p> For example, an application could create a network class loader to
* download class files from a server. Sample code might look like:
*
* <blockquote><pre>
* ClassLoader loader = new NetworkClassLoader(host, port);
* Object main = loader.loadClass("Main", true).newInstance();
* . . .
* </pre></blockquote>
*
* <p> The network class loader subclass must define the methods {@link
* #findClass findClass} and {@code loadClassData} to load a class
* from the network. Once it has downloaded the bytes that make up the class,
* it should use the method {@link #defineClass defineClass} to
* create a class instance. A sample implementation is:
*
* <blockquote><pre>
* class NetworkClassLoader extends ClassLoader {
* String host;
* int port;
*
* public Class findClass(String name) {
* byte[] b = loadClassData(name);
* return defineClass(name, b, 0, b.length);
* }
*
* private byte[] loadClassData(String name) {
* // load the class data from the connection
* . . .
* }
* }
* </pre></blockquote>
*
* <h3> <a id="binary-name">Binary names</a> </h3>
*
* <p> Any class name provided as a {@code String} parameter to methods in
* {@code ClassLoader} must be a binary name as defined by
* <cite>The Java™ Language Specification</cite>.
*
* <p> Examples of valid class names include:
* <blockquote><pre>
* "java.lang.String"
* "javax.swing.JSpinner$DefaultEditor"
* "java.security.KeyStore$Builder$FileBuilder$1"
* "java.net.URLClassLoader$3$1"
* </pre></blockquote>
*
* <p> Any package name provided as a {@code String} parameter to methods in
* {@code ClassLoader} must be either the empty string (denoting an unnamed package)
* or a fully qualified name as defined by
* <cite>The Java™ Language Specification</cite>.
*
* @jls 6.7 Fully Qualified Names
* @jls 13.1 The Form of a Binary
* @see #resolveClass(Class)
* @since 1.0
* @revised 9
* @spec JPMS
*/
public abstract class ClassLoader {
private static native void registerNatives();
static {
registerNatives();
}
// The parent class loader for delegation
// Note: VM hardcoded the offset of this field, thus all new fields
// must be added *after* it.
private final ClassLoader parent;
// class loader name
private final String name;
// the unnamed module for this ClassLoader
private final Module unnamedModule;
// a string for exception message printing
private final String nameAndId;
/**
* Encapsulates the set of parallel capable loader types.
*/
private static class ParallelLoaders {
private ParallelLoaders() {}
// the set of parallel capable loader types
private static final Set<Class<? extends ClassLoader>> loaderTypes =
Collections.newSetFromMap(new WeakHashMap<>());
static {
synchronized (loaderTypes) { loaderTypes.add(ClassLoader.class); }
}
/**
* Registers the given class loader type as parallel capable.
* Returns {@code true} is successfully registered; {@code false} if
* loader's super class is not registered.
*/
static boolean register(Class<? extends ClassLoader> c) {
synchronized (loaderTypes) {
if (loaderTypes.contains(c.getSuperclass())) {
// register the class loader as parallel capable
// if and only if all of its super classes are.
// Note: given current classloading sequence, if
// the immediate super class is parallel capable,
// all the super classes higher up must be too.
loaderTypes.add(c);
return true;
} else {
return false;
}
}
}
/**
* Returns {@code true} if the given class loader type is
* registered as parallel capable.
*/
static boolean isRegistered(Class<? extends ClassLoader> c) {
synchronized (loaderTypes) {
return loaderTypes.contains(c);
}
}
}
// Maps class name to the corresponding lock object when the current
// class loader is parallel capable.
// Note: VM also uses this field to decide if the current class loader
// is parallel capable and the appropriate lock object for class loading.
private final ConcurrentHashMap<String, Object> parallelLockMap;
// Maps packages to certs
private final Map <String, Certificate[]> package2certs;
// Shared among all packages with unsigned classes
private static final Certificate[] nocerts = new Certificate[0];
// The classes loaded by this class loader. The only purpose of this table
// is to keep the classes from being GC'ed until the loader is GC'ed.
private final Vector<Class<?>> classes = new Vector<>();
// The "default" domain. Set as the default ProtectionDomain on newly
// created classes.
private final ProtectionDomain defaultDomain =
new ProtectionDomain(new CodeSource(null, (Certificate[]) null),
null, this, null);
// Invoked by the VM to record every loaded class with this loader.
void addClass(Class<?> c) {
classes.addElement(c);
}
// The packages defined in this class loader. Each package name is
// mapped to its corresponding NamedPackage object.
//
// The value is a Package object if ClassLoader::definePackage,
// Class::getPackage, ClassLoader::getDefinePackage(s) or
// Package::getPackage(s) method is called to define it.
// Otherwise, the value is a NamedPackage object.
private final ConcurrentHashMap<String, NamedPackage> packages
= new ConcurrentHashMap<>();
/*
* Returns a named package for the given module.
*/
private NamedPackage getNamedPackage(String pn, Module m) {
NamedPackage p = packages.get(pn);
if (p == null) {
p = new NamedPackage(pn, m);
NamedPackage value = packages.putIfAbsent(pn, p);
if (value != null) {
// Package object already be defined for the named package
p = value;
// if definePackage is called by this class loader to define
// a package in a named module, this will return Package
// object of the same name. Package object may contain
// unexpected information but it does not impact the runtime.
// this assertion may be helpful for troubleshooting
assert value.module() == m;
}
}
return p;
}
private static Void checkCreateClassLoader() {
return checkCreateClassLoader(null);
}
private static Void checkCreateClassLoader(String name) {
if (name != null && name.isEmpty()) {
throw new IllegalArgumentException("name must be non-empty or null");
}
SecurityManager security = System.getSecurityManager();
if (security != null) {
security.checkCreateClassLoader();
}
return null;
}
private ClassLoader(Void unused, String name, ClassLoader parent) {
this.name = name;
this.parent = parent;
this.unnamedModule = new Module(this);
if (ParallelLoaders.isRegistered(this.getClass())) {
parallelLockMap = new ConcurrentHashMap<>();
package2certs = new ConcurrentHashMap<>();
assertionLock = new Object();
} else {
// no finer-grained lock; lock on the classloader instance
parallelLockMap = null;
package2certs = new Hashtable<>();
assertionLock = this;
}
this.nameAndId = nameAndId(this);
}
/**
* If the defining loader has a name explicitly set then
* '<loader-name>' @<id>
* If the defining loader has no name then
* <qualified-class-name> @<id>
* If it's built-in loader then omit `@<id>` as there is only one instance.
*/
private static String nameAndId(ClassLoader ld) {
String nid = ld.getName() != null ? "\'" + ld.getName() + "\'"
: ld.getClass().getName();
if (!(ld instanceof BuiltinClassLoader)) {
String id = Integer.toHexString(System.identityHashCode(ld));
nid = nid + " @" + id;
}
return nid;
}
/**
* Creates a new class loader of the specified name and using the
* specified parent class loader for delegation.
*
* @apiNote If the parent is specified as {@code null} (for the
* bootstrap class loader) then there is no guarantee that all platform
* classes are visible.
*
* @param name class loader name; or {@code null} if not named
* @param parent the parent class loader
*
* @throws IllegalArgumentException if the given name is empty.
*
* @throws SecurityException
* If a security manager exists and its
* {@link SecurityManager#checkCreateClassLoader()}
* method doesn't allow creation of a new class loader.
*
* @since 9
* @spec JPMS
*/
protected ClassLoader(String name, ClassLoader parent) {
this(checkCreateClassLoader(name), name, parent);
}
/**
* Creates a new class loader using the specified parent class loader for
* delegation.
*
* <p> If there is a security manager, its {@link
* SecurityManager#checkCreateClassLoader() checkCreateClassLoader} method
* is invoked. This may result in a security exception. </p>
*
* @apiNote If the parent is specified as {@code null} (for the
* bootstrap class loader) then there is no guarantee that all platform
* classes are visible.
*
* @param parent
* The parent class loader
*
* @throws SecurityException
* If a security manager exists and its
* {@code checkCreateClassLoader} method doesn't allow creation
* of a new class loader.
*
* @since 1.2
*/
protected ClassLoader(ClassLoader parent) {
this(checkCreateClassLoader(), null, parent);
}
/**
* Creates a new class loader using the {@code ClassLoader} returned by
* the method {@link #getSystemClassLoader()
* getSystemClassLoader()} as the parent class loader.
*
* <p> If there is a security manager, its {@link
* SecurityManager#checkCreateClassLoader()
* checkCreateClassLoader} method is invoked. This may result in
* a security exception. </p>
*
* @throws SecurityException
* If a security manager exists and its
* {@code checkCreateClassLoader} method doesn't allow creation
* of a new class loader.
*/
protected ClassLoader() {
this(checkCreateClassLoader(), null, getSystemClassLoader());
}
/**
* Returns the name of this class loader or {@code null} if
* this class loader is not named.
*
* @apiNote This method is non-final for compatibility. If this
* method is overridden, this method must return the same name
* as specified when this class loader was instantiated.
*
* @return name of this class loader; or {@code null} if
* this class loader is not named.
*
* @since 9
* @spec JPMS
*/
public String getName() {
return name;
}
// package-private used by StackTraceElement to avoid
// calling the overrideable getName method
final String name() {
return name;
}
// -- Class --
/**
* Loads the class with the specified <a href="#binary-name">binary name</a>.
* This method searches for classes in the same manner as the {@link
* #loadClass(String, boolean)} method. It is invoked by the Java virtual
* machine to resolve class references. Invoking this method is equivalent
* to invoking {@link #loadClass(String, boolean) loadClass(name,
* false)}.
*
* @param name
* The <a href="#binary-name">binary name</a> of the class
*
* @return The resulting {@code Class} object
*
* @throws ClassNotFoundException
* If the class was not found
*/
public Class<?> loadClass(String name) throws ClassNotFoundException {
return loadClass(name, false);
}
/**
* Loads the class with the specified <a href="#binary-name">binary name</a>. The
* default implementation of this method searches for classes in the
* following order:
*
* <ol>
*
* <li><p> Invoke {@link #findLoadedClass(String)} to check if the class
* has already been loaded. </p></li>
*
* <li><p> Invoke the {@link #loadClass(String) loadClass} method
* on the parent class loader. If the parent is {@code null} the class
* loader built into the virtual machine is used, instead. </p></li>
*
* <li><p> Invoke the {@link #findClass(String)} method to find the
* class. </p></li>
*
* </ol>
*
* <p> If the class was found using the above steps, and the
* {@code resolve} flag is true, this method will then invoke the {@link
* #resolveClass(Class)} method on the resulting {@code Class} object.
*
* <p> Subclasses of {@code ClassLoader} are encouraged to override {@link
* #findClass(String)}, rather than this method. </p>
*
* <p> Unless overridden, this method synchronizes on the result of
* {@link #getClassLoadingLock getClassLoadingLock} method
* during the entire class loading process.
*
* @param name
* The <a href="#binary-name">binary name</a> of the class
*
* @param resolve
* If {@code true} then resolve the class
*
* @return The resulting {@code Class} object
*
* @throws ClassNotFoundException
* If the class could not be found
*/
protected Class<?> loadClass(String name, boolean resolve)
throws ClassNotFoundException
{
synchronized (getClassLoadingLock(name)) {
// First, check if the class has already been loaded
Class<?> c = findLoadedClass(name);
if (c == null) {
long t0 = System.nanoTime();
try {
if (parent != null) {
c = parent.loadClass(name, false);
} else {
c = findBootstrapClassOrNull(name);
}
} catch (ClassNotFoundException e) {
// ClassNotFoundException thrown if class not found
// from the non-null parent class loader
}
if (c == null) {
// If still not found, then invoke findClass in order
// to find the class.
long t1 = System.nanoTime();
c = findClass(name);
// this is the defining class loader; record the stats
PerfCounter.getParentDelegationTime().addTime(t1 - t0);
PerfCounter.getFindClassTime().addElapsedTimeFrom(t1);
PerfCounter.getFindClasses().increment();
}
}
if (resolve) {
resolveClass(c);
}
return c;
}
}
/**
* Loads the class with the specified <a href="#binary-name">binary name</a>
* in a module defined to this class loader. This method returns {@code null}
* if the class could not be found.
*
* @apiNote This method does not delegate to the parent class loader.
*
* @implSpec The default implementation of this method searches for classes
* in the following order:
*
* <ol>
* <li>Invoke {@link #findLoadedClass(String)} to check if the class
* has already been loaded.</li>
* <li>Invoke the {@link #findClass(String, String)} method to find the
* class in the given module.</li>
* </ol>
*
* @param module
* The module
* @param name
* The <a href="#binary-name">binary name</a> of the class
*
* @return The resulting {@code Class} object in a module defined by
* this class loader, or {@code null} if the class could not be found.
*/
final Class<?> loadClass(Module module, String name) {
synchronized (getClassLoadingLock(name)) {
// First, check if the class has already been loaded
Class<?> c = findLoadedClass(name);
if (c == null) {
c = findClass(module.getName(), name);
}
if (c != null && c.getModule() == module) {
return c;
} else {
return null;
}
}
}
/**
* Returns the lock object for class loading operations.
* For backward compatibility, the default implementation of this method
* behaves as follows. If this ClassLoader object is registered as
* parallel capable, the method returns a dedicated object associated
* with the specified class name. Otherwise, the method returns this
* ClassLoader object.
*
* @param className
* The name of the to-be-loaded class
*
* @return the lock for class loading operations
*
* @throws NullPointerException
* If registered as parallel capable and {@code className} is null
*
* @see #loadClass(String, boolean)
*
* @since 1.7
*/
protected Object getClassLoadingLock(String className) {
Object lock = this;
if (parallelLockMap != null) {
Object newLock = new Object();
lock = parallelLockMap.putIfAbsent(className, newLock);
if (lock == null) {
lock = newLock;
}
}
return lock;
}
// Invoked by the VM after loading class with this loader.
private void checkPackageAccess(Class<?> cls, ProtectionDomain pd) {
final SecurityManager sm = System.getSecurityManager();
if (sm != null) {
if (ReflectUtil.isNonPublicProxyClass(cls)) {
for (Class<?> intf: cls.getInterfaces()) {
checkPackageAccess(intf, pd);
}
return;
}
final String packageName = cls.getPackageName();
if (!packageName.isEmpty()) {
AccessController.doPrivileged(new PrivilegedAction<>() {
public Void run() {
sm.checkPackageAccess(packageName);
return null;
}
}, new AccessControlContext(new ProtectionDomain[] {pd}));
}
}
}
/**
* Finds the class with the specified <a href="#binary-name">binary name</a>.
* This method should be overridden by class loader implementations that
* follow the delegation model for loading classes, and will be invoked by
* the {@link #loadClass loadClass} method after checking the
* parent class loader for the requested class.
*
* @implSpec The default implementation throws {@code ClassNotFoundException}.
*
* @param name
* The <a href="#binary-name">binary name</a> of the class
*
* @return The resulting {@code Class} object
*
* @throws ClassNotFoundException
* If the class could not be found
*
* @since 1.2
*/
protected Class<?> findClass(String name) throws ClassNotFoundException {
throw new ClassNotFoundException(name);
}
/**
* Finds the class with the given <a href="#binary-name">binary name</a>
* in a module defined to this class loader.
* Class loader implementations that support loading from modules
* should override this method.
*
* @apiNote This method returns {@code null} rather than throwing
* {@code ClassNotFoundException} if the class could not be found.
*
* @implSpec The default implementation attempts to find the class by
* invoking {@link #findClass(String)} when the {@code moduleName} is
* {@code null}. It otherwise returns {@code null}.
*
* @param moduleName
* The module name; or {@code null} to find the class in the
* {@linkplain #getUnnamedModule() unnamed module} for this
* class loader
* @param name
* The <a href="#binary-name">binary name</a> of the class
*
* @return The resulting {@code Class} object, or {@code null}
* if the class could not be found.
*
* @since 9
* @spec JPMS
*/
protected Class<?> findClass(String moduleName, String name) {
if (moduleName == null) {
try {
return findClass(name);
} catch (ClassNotFoundException ignore) { }
}
return null;
}
/**
* Converts an array of bytes into an instance of class {@code Class}.
* Before the {@code Class} can be used it must be resolved. This method
* is deprecated in favor of the version that takes a <a
* href="#binary-name">binary name</a> as its first argument, and is more secure.
*
* @param b
* The bytes that make up the class data. The bytes in positions
* {@code off} through {@code off+len-1} should have the format
* of a valid class file as defined by
* <cite>The Java™ Virtual Machine Specification</cite>.
*
* @param off
* The start offset in {@code b} of the class data
*
* @param len
* The length of the class data
*
* @return The {@code Class} object that was created from the specified
* class data
*
* @throws ClassFormatError
* If the data did not contain a valid class
*
* @throws IndexOutOfBoundsException
* If either {@code off} or {@code len} is negative, or if
* {@code off+len} is greater than {@code b.length}.
*
* @throws SecurityException
* If an attempt is made to add this class to a package that
* contains classes that were signed by a different set of
* certificates than this class, or if an attempt is made
* to define a class in a package with a fully-qualified name
* that starts with "{@code java.}".
*
* @see #loadClass(String, boolean)
* @see #resolveClass(Class)
*
* @deprecated Replaced by {@link #defineClass(String, byte[], int, int)
* defineClass(String, byte[], int, int)}
*/
@Deprecated(since="1.1")
protected final Class<?> defineClass(byte[] b, int off, int len)
throws ClassFormatError
{
return defineClass(null, b, off, len, null);
}
/**
* Converts an array of bytes into an instance of class {@code Class}.
* Before the {@code Class} can be used it must be resolved.
*
* <p> This method assigns a default {@link java.security.ProtectionDomain
* ProtectionDomain} to the newly defined class. The
* {@code ProtectionDomain} is effectively granted the same set of
* permissions returned when {@link
* java.security.Policy#getPermissions(java.security.CodeSource)
* Policy.getPolicy().getPermissions(new CodeSource(null, null))}
* is invoked. The default protection domain is created on the first invocation
* of {@link #defineClass(String, byte[], int, int) defineClass},
* and re-used on subsequent invocations.
*
* <p> To assign a specific {@code ProtectionDomain} to the class, use
* the {@link #defineClass(String, byte[], int, int,
* java.security.ProtectionDomain) defineClass} method that takes a
* {@code ProtectionDomain} as one of its arguments. </p>
*
* <p>
* This method defines a package in this class loader corresponding to the
* package of the {@code Class} (if such a package has not already been defined
* in this class loader). The name of the defined package is derived from
* the <a href="#binary-name">binary name</a> of the class specified by
* the byte array {@code b}.
* Other properties of the defined package are as specified by {@link Package}.
*
* @param name
* The expected <a href="#binary-name">binary name</a> of the class, or
* {@code null} if not known
*
* @param b
* The bytes that make up the class data. The bytes in positions
* {@code off} through {@code off+len-1} should have the format
* of a valid class file as defined by
* <cite>The Java™ Virtual Machine Specification</cite>.
*
* @param off
* The start offset in {@code b} of the class data
*
* @param len
* The length of the class data
*
* @return The {@code Class} object that was created from the specified
* class data.
*
* @throws ClassFormatError
* If the data did not contain a valid class
*
* @throws IndexOutOfBoundsException
* If either {@code off} or {@code len} is negative, or if
* {@code off+len} is greater than {@code b.length}.
*
* @throws SecurityException
* If an attempt is made to add this class to a package that
* contains classes that were signed by a different set of
* certificates than this class (which is unsigned), or if
* {@code name} begins with "{@code java.}".
*
* @see #loadClass(String, boolean)
* @see #resolveClass(Class)
* @see java.security.CodeSource
* @see java.security.SecureClassLoader
*
* @since 1.1
* @revised 9
* @spec JPMS
*/
protected final Class<?> defineClass(String name, byte[] b, int off, int len)
throws ClassFormatError
{
return defineClass(name, b, off, len, null);
}
/* Determine protection domain, and check that:
- not define java.* class,
- signer of this class matches signers for the rest of the classes in
package.
*/
private ProtectionDomain preDefineClass(String name,
ProtectionDomain pd)
{
if (!checkName(name))
throw new NoClassDefFoundError("IllegalName: " + name);
// Note: Checking logic in java.lang.invoke.MemberName.checkForTypeAlias
// relies on the fact that spoofing is impossible if a class has a name
// of the form "java.*"
if ((name != null) && name.startsWith("java.")
&& this != getBuiltinPlatformClassLoader()) {
throw new SecurityException
("Prohibited package name: " +
name.substring(0, name.lastIndexOf('.')));
}
if (pd == null) {
pd = defaultDomain;
}
if (name != null) {
checkCerts(name, pd.getCodeSource());
}
return pd;
}
private String defineClassSourceLocation(ProtectionDomain pd) {
CodeSource cs = pd.getCodeSource();
String source = null;
if (cs != null && cs.getLocation() != null) {
source = cs.getLocation().toString();
}
return source;
}
private void postDefineClass(Class<?> c, ProtectionDomain pd) {
// define a named package, if not present
getNamedPackage(c.getPackageName(), c.getModule());
if (pd.getCodeSource() != null) {
Certificate certs[] = pd.getCodeSource().getCertificates();
if (certs != null)
setSigners(c, certs);
}
}
/**
* Converts an array of bytes into an instance of class {@code Class},
* with a given {@code ProtectionDomain}.
*
* <p> If the given {@code ProtectionDomain} is {@code null},
* then a default protection domain will be assigned to the class as specified
* in the documentation for {@link #defineClass(String, byte[], int, int)}.
* Before the class can be used it must be resolved.
*
* <p> The first class defined in a package determines the exact set of
* certificates that all subsequent classes defined in that package must
* contain. The set of certificates for a class is obtained from the
* {@link java.security.CodeSource CodeSource} within the
* {@code ProtectionDomain} of the class. Any classes added to that
* package must contain the same set of certificates or a
* {@code SecurityException} will be thrown. Note that if
* {@code name} is {@code null}, this check is not performed.
* You should always pass in the <a href="#binary-name">binary name</a> of the
* class you are defining as well as the bytes. This ensures that the
* class you are defining is indeed the class you think it is.
*
* <p> If the specified {@code name} begins with "{@code java.}", it can
* only be defined by the {@linkplain #getPlatformClassLoader()
* platform class loader} or its ancestors; otherwise {@code SecurityException}
* will be thrown. If {@code name} is not {@code null}, it must be equal to
* the <a href="#binary-name">binary name</a> of the class
* specified by the byte array {@code b}, otherwise a {@link
* NoClassDefFoundError NoClassDefFoundError} will be thrown.
*
* <p> This method defines a package in this class loader corresponding to the
* package of the {@code Class} (if such a package has not already been defined
* in this class loader). The name of the defined package is derived from
* the <a href="#binary-name">binary name</a> of the class specified by
* the byte array {@code b}.
* Other properties of the defined package are as specified by {@link Package}.
*
* @param name
* The expected <a href="#binary-name">binary name</a> of the class, or
* {@code null} if not known
*
* @param b
* The bytes that make up the class data. The bytes in positions
* {@code off} through {@code off+len-1} should have the format
* of a valid class file as defined by
* <cite>The Java™ Virtual Machine Specification</cite>.
*
* @param off
* The start offset in {@code b} of the class data
*
* @param len
* The length of the class data
*
* @param protectionDomain
* The {@code ProtectionDomain} of the class
*
* @return The {@code Class} object created from the data,
* and {@code ProtectionDomain}.
*
* @throws ClassFormatError
* If the data did not contain a valid class
*
* @throws NoClassDefFoundError
* If {@code name} is not {@code null} and not equal to the
* <a href="#binary-name">binary name</a> of the class specified by {@code b}
*
* @throws IndexOutOfBoundsException
* If either {@code off} or {@code len} is negative, or if
* {@code off+len} is greater than {@code b.length}.
*
* @throws SecurityException
* If an attempt is made to add this class to a package that
* contains classes that were signed by a different set of
* certificates than this class, or if {@code name} begins with
* "{@code java.}" and this class loader is not the platform
* class loader or its ancestor.
*
* @revised 9
* @spec JPMS
*/
protected final Class<?> defineClass(String name, byte[] b, int off, int len,
ProtectionDomain protectionDomain)
throws ClassFormatError
{
protectionDomain = preDefineClass(name, protectionDomain);
String source = defineClassSourceLocation(protectionDomain);
Class<?> c = defineClass1(this, name, b, off, len, protectionDomain, source);
postDefineClass(c, protectionDomain);
return c;
}
/**
* Converts a {@link java.nio.ByteBuffer ByteBuffer} into an instance
* of class {@code Class}, with the given {@code ProtectionDomain}.
* If the given {@code ProtectionDomain} is {@code null}, then a default
* protection domain will be assigned to the class as
* specified in the documentation for {@link #defineClass(String, byte[],
* int, int)}. Before the class can be used it must be resolved.
*
* <p>The rules about the first class defined in a package determining the
* set of certificates for the package, the restrictions on class names,
* and the defined package of the class
* are identical to those specified in the documentation for {@link
* #defineClass(String, byte[], int, int, ProtectionDomain)}.
*
* <p> An invocation of this method of the form
* <i>cl</i>{@code .defineClass(}<i>name</i>{@code ,}
* <i>bBuffer</i>{@code ,} <i>pd</i>{@code )} yields exactly the same
* result as the statements
*
*<p> <code>
* ...<br>
* byte[] temp = new byte[bBuffer.{@link
* java.nio.ByteBuffer#remaining remaining}()];<br>
* bBuffer.{@link java.nio.ByteBuffer#get(byte[])
* get}(temp);<br>
* return {@link #defineClass(String, byte[], int, int, ProtectionDomain)
* cl.defineClass}(name, temp, 0,
* temp.length, pd);<br>
* </code></p>
*
* @param name
* The expected <a href="#binary-name">binary name</a>. of the class, or
* {@code null} if not known
*
* @param b
* The bytes that make up the class data. The bytes from positions
* {@code b.position()} through {@code b.position() + b.limit() -1
* } should have the format of a valid class file as defined by
* <cite>The Java™ Virtual Machine Specification</cite>.
*
* @param protectionDomain
* The {@code ProtectionDomain} of the class, or {@code null}.
*
* @return The {@code Class} object created from the data,
* and {@code ProtectionDomain}.
*
* @throws ClassFormatError
* If the data did not contain a valid class.
*
* @throws NoClassDefFoundError
* If {@code name} is not {@code null} and not equal to the
* <a href="#binary-name">binary name</a> of the class specified by {@code b}
*
* @throws SecurityException
* If an attempt is made to add this class to a package that
* contains classes that were signed by a different set of
* certificates than this class, or if {@code name} begins with
* "{@code java.}".
*
* @see #defineClass(String, byte[], int, int, ProtectionDomain)
*
* @since 1.5
* @revised 9
* @spec JPMS
*/
protected final Class<?> defineClass(String name, java.nio.ByteBuffer b,
ProtectionDomain protectionDomain)
throws ClassFormatError
{
int len = b.remaining();
// Use byte[] if not a direct ByteBuffer:
if (!b.isDirect()) {
if (b.hasArray()) {
return defineClass(name, b.array(),
b.position() + b.arrayOffset(), len,
protectionDomain);
} else {
// no array, or read-only array
byte[] tb = new byte[len];
b.get(tb); // get bytes out of byte buffer.
return defineClass(name, tb, 0, len, protectionDomain);
}
}
protectionDomain = preDefineClass(name, protectionDomain);
String source = defineClassSourceLocation(protectionDomain);
Class<?> c = defineClass2(this, name, b, b.position(), len, protectionDomain, source);
postDefineClass(c, protectionDomain);
return c;
}
static native Class<?> defineClass1(ClassLoader loader, String name, byte[] b, int off, int len,
ProtectionDomain pd, String source);
static native Class<?> defineClass2(ClassLoader loader, String name, java.nio.ByteBuffer b,
int off, int len, ProtectionDomain pd,
String source);
// true if the name is null or has the potential to be a valid binary name
private boolean checkName(String name) {
if ((name == null) || (name.length() == 0))
return true;
if ((name.indexOf('/') != -1) || (name.charAt(0) == '['))
return false;
return true;
}
private void checkCerts(String name, CodeSource cs) {
int i = name.lastIndexOf('.');
String pname = (i == -1) ? "" : name.substring(0, i);
Certificate[] certs = null;
if (cs != null) {
certs = cs.getCertificates();
}
Certificate[] pcerts = null;
if (parallelLockMap == null) {
synchronized (this) {
pcerts = package2certs.get(pname);
if (pcerts == null) {
package2certs.put(pname, (certs == null? nocerts:certs));
}
}
} else {
pcerts = ((ConcurrentHashMap<String, Certificate[]>)package2certs).
putIfAbsent(pname, (certs == null? nocerts:certs));
}
if (pcerts != null && !compareCerts(pcerts, certs)) {
throw new SecurityException("class \"" + name
+ "\"'s signer information does not match signer information"
+ " of other classes in the same package");
}
}
/**
* check to make sure the certs for the new class (certs) are the same as
* the certs for the first class inserted in the package (pcerts)
*/
private boolean compareCerts(Certificate[] pcerts,
Certificate[] certs)
{
// certs can be null, indicating no certs.
if ((certs == null) || (certs.length == 0)) {
return pcerts.length == 0;
}
// the length must be the same at this point
if (certs.length != pcerts.length)
return false;
// go through and make sure all the certs in one array
// are in the other and vice-versa.
boolean match;
for (Certificate cert : certs) {
match = false;
for (Certificate pcert : pcerts) {
if (cert.equals(pcert)) {
match = true;
break;
}
}
if (!match) return false;
}
// now do the same for pcerts
for (Certificate pcert : pcerts) {
match = false;
for (Certificate cert : certs) {
if (pcert.equals(cert)) {
match = true;
break;
}
}
if (!match) return false;
}
return true;
}
/**
* Links the specified class. This (misleadingly named) method may be
* used by a class loader to link a class. If the class {@code c} has
* already been linked, then this method simply returns. Otherwise, the
* class is linked as described in the "Execution" chapter of
* <cite>The Java™ Language Specification</cite>.
*
* @param c
* The class to link
*
* @throws NullPointerException
* If {@code c} is {@code null}.
*
* @see #defineClass(String, byte[], int, int)
*/
protected final void resolveClass(Class<?> c) {
if (c == null) {
throw new NullPointerException();
}
}
/**
* Finds a class with the specified <a href="#binary-name">binary name</a>,
* loading it if necessary.
*
* <p> This method loads the class through the system class loader (see
* {@link #getSystemClassLoader()}). The {@code Class} object returned
* might have more than one {@code ClassLoader} associated with it.
* Subclasses of {@code ClassLoader} need not usually invoke this method,
* because most class loaders need to override just {@link
* #findClass(String)}. </p>
*
* @param name
* The <a href="#binary-name">binary name</a> of the class
*
* @return The {@code Class} object for the specified {@code name}
*
* @throws ClassNotFoundException
* If the class could not be found
*
* @see #ClassLoader(ClassLoader)
* @see #getParent()
*/
protected final Class<?> findSystemClass(String name)
throws ClassNotFoundException
{
return getSystemClassLoader().loadClass(name);
}
/**
* Returns a class loaded by the bootstrap class loader;
* or return null if not found.
*/
Class<?> findBootstrapClassOrNull(String name) {
if (!checkName(name)) return null;
return findBootstrapClass(name);
}
// return null if not found
private native Class<?> findBootstrapClass(String name);
/**
* Returns the class with the given <a href="#binary-name">binary name</a> if this
* loader has been recorded by the Java virtual machine as an initiating
* loader of a class with that <a href="#binary-name">binary name</a>. Otherwise
* {@code null} is returned.
*
* @param name
* The <a href="#binary-name">binary name</a> of the class
*
* @return The {@code Class} object, or {@code null} if the class has
* not been loaded
*
* @since 1.1
*/
protected final Class<?> findLoadedClass(String name) {
if (!checkName(name))
return null;
return findLoadedClass0(name);
}
private final native Class<?> findLoadedClass0(String name);
/**
* Sets the signers of a class. This should be invoked after defining a
* class.
*
* @param c
* The {@code Class} object
*
* @param signers
* The signers for the class
*
* @since 1.1
*/
protected final void setSigners(Class<?> c, Object[] signers) {
c.setSigners(signers);
}
// -- Resources --
/**
* Returns a URL to a resource in a module defined to this class loader.
* Class loader implementations that support loading from modules
* should override this method.
*
* @apiNote This method is the basis for the {@link
* Class#getResource Class.getResource}, {@link Class#getResourceAsStream
* Class.getResourceAsStream}, and {@link Module#getResourceAsStream
* Module.getResourceAsStream} methods. It is not subject to the rules for
* encapsulation specified by {@code Module.getResourceAsStream}.
*
* @implSpec The default implementation attempts to find the resource by
* invoking {@link #findResource(String)} when the {@code moduleName} is
* {@code null}. It otherwise returns {@code null}.
*
* @param moduleName
* The module name; or {@code null} to find a resource in the
* {@linkplain #getUnnamedModule() unnamed module} for this
* class loader
* @param name
* The resource name
*
* @return A URL to the resource; {@code null} if the resource could not be
* found, a URL could not be constructed to locate the resource,
* access to the resource is denied by the security manager, or
* there isn't a module of the given name defined to the class
* loader.
*
* @throws IOException
* If I/O errors occur
*
* @see java.lang.module.ModuleReader#find(String)
* @since 9
* @spec JPMS
*/
protected URL findResource(String moduleName, String name) throws IOException {
if (moduleName == null) {
return findResource(name);
} else {
return null;
}
}
/**
* Finds the resource with the given name. A resource is some data
* (images, audio, text, etc) that can be accessed by class code in a way
* that is independent of the location of the code.
*
* <p> The name of a resource is a '{@code /}'-separated path name that
* identifies the resource. </p>
*
* <p> Resources in named modules are subject to the encapsulation rules
* specified by {@link Module#getResourceAsStream Module.getResourceAsStream}.
* Additionally, and except for the special case where the resource has a
* name ending with "{@code .class}", this method will only find resources in
* packages of named modules when the package is {@link Module#isOpen(String)
* opened} unconditionally (even if the caller of this method is in the
* same module as the resource). </p>
*
* @implSpec The default implementation will first search the parent class
* loader for the resource; if the parent is {@code null} the path of the
* class loader built into the virtual machine is searched. If not found,
* this method will invoke {@link #findResource(String)} to find the resource.
*
* @apiNote Where several modules are defined to the same class loader,
* and where more than one module contains a resource with the given name,
* then the ordering that modules are searched is not specified and may be
* very unpredictable.
* When overriding this method it is recommended that an implementation
* ensures that any delegation is consistent with the {@link
* #getResources(java.lang.String) getResources(String)} method.
*
* @param name
* The resource name
*
* @return {@code URL} object for reading the resource; {@code null} if
* the resource could not be found, a {@code URL} could not be
* constructed to locate the resource, the resource is in a package
* that is not opened unconditionally, or access to the resource is
* denied by the security manager.
*
* @throws NullPointerException If {@code name} is {@code null}
*
* @since 1.1
* @revised 9
* @spec JPMS
*/
public URL getResource(String name) {
Objects.requireNonNull(name);
URL url;
if (parent != null) {
url = parent.getResource(name);
} else {
url = BootLoader.findResource(name);
}
if (url == null) {
url = findResource(name);
}
return url;
}
/**
* Finds all the resources with the given name. A resource is some data
* (images, audio, text, etc) that can be accessed by class code in a way
* that is independent of the location of the code.
*
* <p> The name of a resource is a {@code /}-separated path name that
* identifies the resource. </p>
*
* <p> Resources in named modules are subject to the encapsulation rules
* specified by {@link Module#getResourceAsStream Module.getResourceAsStream}.
* Additionally, and except for the special case where the resource has a
* name ending with "{@code .class}", this method will only find resources in
* packages of named modules when the package is {@link Module#isOpen(String)
* opened} unconditionally (even if the caller of this method is in the
* same module as the resource). </p>
*
* @implSpec The default implementation will first search the parent class
* loader for the resource; if the parent is {@code null} the path of the
* class loader built into the virtual machine is searched. It then
* invokes {@link #findResources(String)} to find the resources with the
* name in this class loader. It returns an enumeration whose elements
* are the URLs found by searching the parent class loader followed by
* the elements found with {@code findResources}.
*
* @apiNote Where several modules are defined to the same class loader,
* and where more than one module contains a resource with the given name,
* then the ordering is not specified and may be very unpredictable.
* When overriding this method it is recommended that an
* implementation ensures that any delegation is consistent with the {@link
* #getResource(java.lang.String) getResource(String)} method. This should
* ensure that the first element returned by the Enumeration's
* {@code nextElement} method is the same resource that the
* {@code getResource(String)} method would return.
*
* @param name
* The resource name
*
* @return An enumeration of {@link java.net.URL URL} objects for the
* resource. If no resources could be found, the enumeration will
* be empty. Resources for which a {@code URL} cannot be
* constructed, are in a package that is not opened
* unconditionally, or access to the resource is denied by the
* security manager, are not returned in the enumeration.
*
* @throws IOException
* If I/O errors occur
* @throws NullPointerException If {@code name} is {@code null}
*
* @since 1.2
* @revised 9
* @spec JPMS
*/
public Enumeration<URL> getResources(String name) throws IOException {
Objects.requireNonNull(name);
@SuppressWarnings("unchecked")
Enumeration<URL>[] tmp = (Enumeration<URL>[]) new Enumeration<?>[2];
if (parent != null) {
tmp[0] = parent.getResources(name);
} else {
tmp[0] = BootLoader.findResources(name);
}
tmp[1] = findResources(name);
return new CompoundEnumeration<>(tmp);
}
/**
* Returns a stream whose elements are the URLs of all the resources with
* the given name. A resource is some data (images, audio, text, etc) that
* can be accessed by class code in a way that is independent of the
* location of the code.
*
* <p> The name of a resource is a {@code /}-separated path name that
* identifies the resource.
*
* <p> The resources will be located when the returned stream is evaluated.
* If the evaluation results in an {@code IOException} then the I/O
* exception is wrapped in an {@link UncheckedIOException} that is then
* thrown.
*
* <p> Resources in named modules are subject to the encapsulation rules
* specified by {@link Module#getResourceAsStream Module.getResourceAsStream}.
* Additionally, and except for the special case where the resource has a
* name ending with "{@code .class}", this method will only find resources in
* packages of named modules when the package is {@link Module#isOpen(String)
* opened} unconditionally (even if the caller of this method is in the
* same module as the resource). </p>
*
* @implSpec The default implementation invokes {@link #getResources(String)
* getResources} to find all the resources with the given name and returns
* a stream with the elements in the enumeration as the source.
*
* @apiNote When overriding this method it is recommended that an
* implementation ensures that any delegation is consistent with the {@link
* #getResource(java.lang.String) getResource(String)} method. This should
* ensure that the first element returned by the stream is the same
* resource that the {@code getResource(String)} method would return.
*
* @param name
* The resource name
*
* @return A stream of resource {@link java.net.URL URL} objects. If no
* resources could be found, the stream will be empty. Resources
* for which a {@code URL} cannot be constructed, are in a package
* that is not opened unconditionally, or access to the resource
* is denied by the security manager, will not be in the stream.
*
* @throws NullPointerException If {@code name} is {@code null}
*
* @since 9
*/
public Stream<URL> resources(String name) {
Objects.requireNonNull(name);
int characteristics = Spliterator.NONNULL | Spliterator.IMMUTABLE;
Supplier<Spliterator<URL>> si = () -> {
try {
return Spliterators.spliteratorUnknownSize(
getResources(name).asIterator(), characteristics);
} catch (IOException e) {
throw new UncheckedIOException(e);
}
};
return StreamSupport.stream(si, characteristics, false);
}
/**
* Finds the resource with the given name. Class loader implementations
* should override this method.
*
* <p> For resources in named modules then the method must implement the
* rules for encapsulation specified in the {@code Module} {@link
* Module#getResourceAsStream getResourceAsStream} method. Additionally,
* it must not find non-"{@code .class}" resources in packages of named
* modules unless the package is {@link Module#isOpen(String) opened}
* unconditionally. </p>
*
* @implSpec The default implementation returns {@code null}.
*
* @param name
* The resource name
*
* @return {@code URL} object for reading the resource; {@code null} if
* the resource could not be found, a {@code URL} could not be
* constructed to locate the resource, the resource is in a package
* that is not opened unconditionally, or access to the resource is
* denied by the security manager.
*
* @since 1.2
* @revised 9
* @spec JPMS
*/
protected URL findResource(String name) {
return null;
}
/**
* Returns an enumeration of {@link java.net.URL URL} objects
* representing all the resources with the given name. Class loader
* implementations should override this method.
*
* <p> For resources in named modules then the method must implement the
* rules for encapsulation specified in the {@code Module} {@link
* Module#getResourceAsStream getResourceAsStream} method. Additionally,
* it must not find non-"{@code .class}" resources in packages of named
* modules unless the package is {@link Module#isOpen(String) opened}
* unconditionally. </p>
*
* @implSpec The default implementation returns an enumeration that
* contains no elements.
*
* @param name
* The resource name
*
* @return An enumeration of {@link java.net.URL URL} objects for
* the resource. If no resources could be found, the enumeration
* will be empty. Resources for which a {@code URL} cannot be
* constructed, are in a package that is not opened unconditionally,
* or access to the resource is denied by the security manager,
* are not returned in the enumeration.
*
* @throws IOException
* If I/O errors occur
*
* @since 1.2
* @revised 9
* @spec JPMS
*/
protected Enumeration<URL> findResources(String name) throws IOException {
return Collections.emptyEnumeration();
}
/**
* Registers the caller as
* {@linkplain #isRegisteredAsParallelCapable() parallel capable}.
* The registration succeeds if and only if all of the following
* conditions are met:
* <ol>
* <li> no instance of the caller has been created</li>
* <li> all of the super classes (except class Object) of the caller are
* registered as parallel capable</li>
* </ol>
* <p>Note that once a class loader is registered as parallel capable, there
* is no way to change it back.</p>
*
* @return {@code true} if the caller is successfully registered as
* parallel capable and {@code false} if otherwise.
*
* @see #isRegisteredAsParallelCapable()
*
* @since 1.7
*/
@CallerSensitive
protected static boolean registerAsParallelCapable() {
Class<? extends ClassLoader> callerClass =
Reflection.getCallerClass().asSubclass(ClassLoader.class);
return ParallelLoaders.register(callerClass);
}
/**
* Returns {@code true} if this class loader is registered as
* {@linkplain #registerAsParallelCapable parallel capable}, otherwise
* {@code false}.
*
* @return {@code true} if this class loader is parallel capable,
* otherwise {@code false}.
*
* @see #registerAsParallelCapable()
*
* @since 9
*/
public final boolean isRegisteredAsParallelCapable() {
return ParallelLoaders.isRegistered(this.getClass());
}
/**
* Find a resource of the specified name from the search path used to load
* classes. This method locates the resource through the system class
* loader (see {@link #getSystemClassLoader()}).
*
* <p> Resources in named modules are subject to the encapsulation rules
* specified by {@link Module#getResourceAsStream Module.getResourceAsStream}.
* Additionally, and except for the special case where the resource has a
* name ending with "{@code .class}", this method will only find resources in
* packages of named modules when the package is {@link Module#isOpen(String)
* opened} unconditionally. </p>
*
* @param name
* The resource name
*
* @return A {@link java.net.URL URL} to the resource; {@code
* null} if the resource could not be found, a URL could not be
* constructed to locate the resource, the resource is in a package
* that is not opened unconditionally or access to the resource is
* denied by the security manager.
*
* @since 1.1
* @revised 9
* @spec JPMS
*/
public static URL getSystemResource(String name) {
return getSystemClassLoader().getResource(name);
}
/**
* Finds all resources of the specified name from the search path used to
* load classes. The resources thus found are returned as an
* {@link java.util.Enumeration Enumeration} of {@link
* java.net.URL URL} objects.
*
* <p> The search order is described in the documentation for {@link
* #getSystemResource(String)}. </p>
*
* <p> Resources in named modules are subject to the encapsulation rules
* specified by {@link Module#getResourceAsStream Module.getResourceAsStream}.
* Additionally, and except for the special case where the resource has a
* name ending with "{@code .class}", this method will only find resources in
* packages of named modules when the package is {@link Module#isOpen(String)
* opened} unconditionally. </p>
*
* @param name
* The resource name
*
* @return An enumeration of {@link java.net.URL URL} objects for
* the resource. If no resources could be found, the enumeration
* will be empty. Resources for which a {@code URL} cannot be
* constructed, are in a package that is not opened unconditionally,
* or access to the resource is denied by the security manager,
* are not returned in the enumeration.
*
* @throws IOException
* If I/O errors occur
*
* @since 1.2
* @revised 9
* @spec JPMS
*/
public static Enumeration<URL> getSystemResources(String name)
throws IOException
{
return getSystemClassLoader().getResources(name);
}
/**
* Returns an input stream for reading the specified resource.
*
* <p> The search order is described in the documentation for {@link
* #getResource(String)}. </p>
*
* <p> Resources in named modules are subject to the encapsulation rules
* specified by {@link Module#getResourceAsStream Module.getResourceAsStream}.
* Additionally, and except for the special case where the resource has a
* name ending with "{@code .class}", this method will only find resources in
* packages of named modules when the package is {@link Module#isOpen(String)
* opened} unconditionally. </p>
*
* @param name
* The resource name
*
* @return An input stream for reading the resource; {@code null} if the
* resource could not be found, the resource is in a package that
* is not opened unconditionally, or access to the resource is
* denied by the security manager.
*
* @throws NullPointerException If {@code name} is {@code null}
*
* @since 1.1
* @revised 9
* @spec JPMS
*/
public InputStream getResourceAsStream(String name) {
Objects.requireNonNull(name);
URL url = getResource(name);
try {
return url != null ? url.openStream() : null;
} catch (IOException e) {
return null;
}
}
/**
* Open for reading, a resource of the specified name from the search path
* used to load classes. This method locates the resource through the
* system class loader (see {@link #getSystemClassLoader()}).
*
* <p> Resources in named modules are subject to the encapsulation rules
* specified by {@link Module#getResourceAsStream Module.getResourceAsStream}.
* Additionally, and except for the special case where the resource has a
* name ending with "{@code .class}", this method will only find resources in
* packages of named modules when the package is {@link Module#isOpen(String)
* opened} unconditionally. </p>
*
* @param name
* The resource name
*
* @return An input stream for reading the resource; {@code null} if the
* resource could not be found, the resource is in a package that
* is not opened unconditionally, or access to the resource is
* denied by the security manager.
*
* @since 1.1
* @revised 9
* @spec JPMS
*/
public static InputStream getSystemResourceAsStream(String name) {
URL url = getSystemResource(name);
try {
return url != null ? url.openStream() : null;
} catch (IOException e) {
return null;
}
}
// -- Hierarchy --
/**
* Returns the parent class loader for delegation. Some implementations may
* use {@code null} to represent the bootstrap class loader. This method
* will return {@code null} in such implementations if this class loader's
* parent is the bootstrap class loader.
*
* @return The parent {@code ClassLoader}
*
* @throws SecurityException
* If a security manager is present, and the caller's class loader
* is not {@code null} and is not an ancestor of this class loader,
* and the caller does not have the
* {@link RuntimePermission}{@code ("getClassLoader")}
*
* @since 1.2
*/
@CallerSensitive
public final ClassLoader getParent() {
if (parent == null)
return null;
SecurityManager sm = System.getSecurityManager();
if (sm != null) {
// Check access to the parent class loader
// If the caller's class loader is same as this class loader,
// permission check is performed.
checkClassLoaderPermission(parent, Reflection.getCallerClass());
}
return parent;
}
/**
* Returns the unnamed {@code Module} for this class loader.
*
* @return The unnamed Module for this class loader
*
* @see Module#isNamed()
* @since 9
* @spec JPMS
*/
public final Module getUnnamedModule() {
return unnamedModule;
}
/**
* Returns the platform class loader. All
* <a href="#builtinLoaders">platform classes</a> are visible to
* the platform class loader.
*
* @implNote The name of the builtin platform class loader is
* {@code "platform"}.
*
* @return The platform {@code ClassLoader}.
*
* @throws SecurityException
* If a security manager is present, and the caller's class loader is
* not {@code null}, and the caller's class loader is not the same
* as or an ancestor of the platform class loader,
* and the caller does not have the
* {@link RuntimePermission}{@code ("getClassLoader")}
*
* @since 9
* @spec JPMS
*/
@CallerSensitive
public static ClassLoader getPlatformClassLoader() {
SecurityManager sm = System.getSecurityManager();
ClassLoader loader = getBuiltinPlatformClassLoader();
if (sm != null) {
checkClassLoaderPermission(loader, Reflection.getCallerClass());
}
return loader;
}
/**
* Returns the system class loader. This is the default
* delegation parent for new {@code ClassLoader} instances, and is
* typically the class loader used to start the application.
*
* <p> This method is first invoked early in the runtime's startup
* sequence, at which point it creates the system class loader. This
* class loader will be the context class loader for the main application
* thread (for example, the thread that invokes the {@code main} method of
* the main class).
*
* <p> The default system class loader is an implementation-dependent
* instance of this class.
*
* <p> If the system property "{@code java.system.class.loader}" is defined
* when this method is first invoked then the value of that property is
* taken to be the name of a class that will be returned as the system
* class loader. The class is loaded using the default system class loader
* and must define a public constructor that takes a single parameter of
* type {@code ClassLoader} which is used as the delegation parent. An
* instance is then created using this constructor with the default system
* class loader as the parameter. The resulting class loader is defined
* to be the system class loader. During construction, the class loader
* should take great care to avoid calling {@code getSystemClassLoader()}.
* If circular initialization of the system class loader is detected then
* an {@code IllegalStateException} is thrown.
*
* @implNote The system property to override the system class loader is not
* examined until the VM is almost fully initialized. Code that executes
* this method during startup should take care not to cache the return
* value until the system is fully initialized.
*
* <p> The name of the built-in system class loader is {@code "app"}.
* The system property "{@code java.class.path}" is read during early
* initialization of the VM to determine the class path.
* An empty value of "{@code java.class.path}" property is interpreted
* differently depending on whether the initial module (the module
* containing the main class) is named or unnamed:
* If named, the built-in system class loader will have no class path and
* will search for classes and resources using the application module path;
* otherwise, if unnamed, it will set the class path to the current
* working directory.
*
* @return The system {@code ClassLoader}
*
* @throws SecurityException
* If a security manager is present, and the caller's class loader
* is not {@code null} and is not the same as or an ancestor of the
* system class loader, and the caller does not have the
* {@link RuntimePermission}{@code ("getClassLoader")}
*
* @throws IllegalStateException
* If invoked recursively during the construction of the class
* loader specified by the "{@code java.system.class.loader}"
* property.
*
* @throws Error
* If the system property "{@code java.system.class.loader}"
* is defined but the named class could not be loaded, the
* provider class does not define the required constructor, or an
* exception is thrown by that constructor when it is invoked. The
* underlying cause of the error can be retrieved via the
* {@link Throwable#getCause()} method.
*
* @revised 1.4
* @revised 9
* @spec JPMS
*/
@CallerSensitive
public static ClassLoader getSystemClassLoader() {
switch (VM.initLevel()) {
case 0:
case 1:
case 2:
// the system class loader is the built-in app class loader during startup
return getBuiltinAppClassLoader();
case 3:
String msg = "getSystemClassLoader cannot be called during the system class loader instantiation";
throw new IllegalStateException(msg);
default:
// system fully initialized
assert VM.isBooted() && scl != null;
SecurityManager sm = System.getSecurityManager();
if (sm != null) {
checkClassLoaderPermission(scl, Reflection.getCallerClass());
}
return scl;
}
}
static ClassLoader getBuiltinPlatformClassLoader() {
return ClassLoaders.platformClassLoader();
}
static ClassLoader getBuiltinAppClassLoader() {
return ClassLoaders.appClassLoader();
}
/*
* Initialize the system class loader that may be a custom class on the
* application class path or application module path.
*
* @see java.lang.System#initPhase3
*/
static synchronized ClassLoader initSystemClassLoader() {
if (VM.initLevel() != 3) {
throw new InternalError("system class loader cannot be set at initLevel " +
VM.initLevel());
}
// detect recursive initialization
if (scl != null) {
throw new IllegalStateException("recursive invocation");
}
ClassLoader builtinLoader = getBuiltinAppClassLoader();
// All are privileged frames. No need to call doPrivileged.
String cn = System.getProperty("java.system.class.loader");
if (cn != null) {
try {
// custom class loader is only supported to be loaded from unnamed module
Constructor<?> ctor = Class.forName(cn, false, builtinLoader)
.getDeclaredConstructor(ClassLoader.class);
scl = (ClassLoader) ctor.newInstance(builtinLoader);
} catch (Exception e) {
Throwable cause = e;
if (e instanceof InvocationTargetException) {
cause = e.getCause();
if (cause instanceof Error) {
throw (Error) cause;
}
}
if (cause instanceof RuntimeException) {
throw (RuntimeException) cause;
}
throw new Error(cause.getMessage(), cause);
}
} else {
scl = builtinLoader;
}
return scl;
}
// Returns true if the specified class loader can be found in this class
// loader's delegation chain.
boolean isAncestor(ClassLoader cl) {
ClassLoader acl = this;
do {
acl = acl.parent;
if (cl == acl) {
return true;
}
} while (acl != null);
return false;
}
// Tests if class loader access requires "getClassLoader" permission
// check. A class loader 'from' can access class loader 'to' if
// class loader 'from' is same as class loader 'to' or an ancestor
// of 'to'. The class loader in a system domain can access
// any class loader.
private static boolean needsClassLoaderPermissionCheck(ClassLoader from,
ClassLoader to)
{
if (from == to)
return false;
if (from == null)
return false;
return !to.isAncestor(from);
}
// Returns the class's class loader, or null if none.
static ClassLoader getClassLoader(Class<?> caller) {
// This can be null if the VM is requesting it
if (caller == null) {
return null;
}
// Circumvent security check since this is package-private
return caller.getClassLoader0();
}
/*
* Checks RuntimePermission("getClassLoader") permission
* if caller's class loader is not null and caller's class loader
* is not the same as or an ancestor of the given cl argument.
*/
static void checkClassLoaderPermission(ClassLoader cl, Class<?> caller) {
SecurityManager sm = System.getSecurityManager();
if (sm != null) {
// caller can be null if the VM is requesting it
ClassLoader ccl = getClassLoader(caller);
if (needsClassLoaderPermissionCheck(ccl, cl)) {
sm.checkPermission(SecurityConstants.GET_CLASSLOADER_PERMISSION);
}
}
}
// The system class loader
// @GuardedBy("ClassLoader.class")
private static volatile ClassLoader scl;
// -- Package --
/**
* Define a Package of the given Class object.
*
* If the given class represents an array type, a primitive type or void,
* this method returns {@code null}.
*
* This method does not throw IllegalArgumentException.
*/
Package definePackage(Class<?> c) {
if (c.isPrimitive() || c.isArray()) {
return null;
}
return definePackage(c.getPackageName(), c.getModule());
}
/**
* Defines a Package of the given name and module
*
* This method does not throw IllegalArgumentException.
*
* @param name package name
* @param m module
*/
Package definePackage(String name, Module m) {
if (name.isEmpty() && m.isNamed()) {
throw new InternalError("unnamed package in " + m);
}
// check if Package object is already defined
NamedPackage pkg = packages.get(name);
if (pkg instanceof Package)
return (Package)pkg;
return (Package)packages.compute(name, (n, p) -> toPackage(n, p, m));
}
/*
* Returns a Package object for the named package
*/
private Package toPackage(String name, NamedPackage p, Module m) {
// define Package object if the named package is not yet defined
if (p == null)
return NamedPackage.toPackage(name, m);
// otherwise, replace the NamedPackage object with Package object
if (p instanceof Package)
return (Package)p;
return NamedPackage.toPackage(p.packageName(), p.module());
}
/**
* Defines a package by <a href="#binary-name">name</a> in this {@code ClassLoader}.
* <p>
* <a href="#binary-name">Package names</a> must be unique within a class loader and
* cannot be redefined or changed once created.
* <p>
* If a class loader wishes to define a package with specific properties,
* such as version information, then the class loader should call this
* {@code definePackage} method before calling {@code defineClass}.
* Otherwise, the
* {@link #defineClass(String, byte[], int, int, ProtectionDomain) defineClass}
* method will define a package in this class loader corresponding to the package
* of the newly defined class; the properties of this defined package are
* specified by {@link Package}.
*
* @apiNote
* A class loader that wishes to define a package for classes in a JAR
* typically uses the specification and implementation titles, versions, and
* vendors from the JAR's manifest. If the package is specified as
* {@linkplain java.util.jar.Attributes.Name#SEALED sealed} in the JAR's manifest,
* the {@code URL} of the JAR file is typically used as the {@code sealBase}.
* If classes of package {@code 'p'} defined by this class loader
* are loaded from multiple JARs, the {@code Package} object may contain
* different information depending on the first class of package {@code 'p'}
* defined and which JAR's manifest is read first to explicitly define
* package {@code 'p'}.
*
* <p> It is strongly recommended that a class loader does not call this
* method to explicitly define packages in <em>named modules</em>; instead,
* the package will be automatically defined when a class is {@linkplain
* #defineClass(String, byte[], int, int, ProtectionDomain) being defined}.
* If it is desirable to define {@code Package} explicitly, it should ensure
* that all packages in a named module are defined with the properties
* specified by {@link Package}. Otherwise, some {@code Package} objects
* in a named module may be for example sealed with different seal base.
*
* @param name
* The <a href="#binary-name">package name</a>
*
* @param specTitle
* The specification title
*
* @param specVersion
* The specification version
*
* @param specVendor
* The specification vendor
*
* @param implTitle
* The implementation title
*
* @param implVersion
* The implementation version
*
* @param implVendor
* The implementation vendor
*
* @param sealBase
* If not {@code null}, then this package is sealed with
* respect to the given code source {@link java.net.URL URL}
* object. Otherwise, the package is not sealed.
*
* @return The newly defined {@code Package} object
*
* @throws NullPointerException
* if {@code name} is {@code null}.
*
* @throws IllegalArgumentException
* if a package of the given {@code name} is already
* defined by this class loader
*
*
* @since 1.2
* @revised 9
* @spec JPMS
*
* @jvms 5.3 Run-time package
* @see <a href="{@docRoot}/../specs/jar/jar.html#package-sealing">
* The JAR File Specification: Package Sealing</a>
*/
protected Package definePackage(String name, String specTitle,
String specVersion, String specVendor,
String implTitle, String implVersion,
String implVendor, URL sealBase)
{
Objects.requireNonNull(name);
// definePackage is not final and may be overridden by custom class loader
Package p = new Package(name, specTitle, specVersion, specVendor,
implTitle, implVersion, implVendor,
sealBase, this);
if (packages.putIfAbsent(name, p) != null)
throw new IllegalArgumentException(name);
return p;
}
/**
* Returns a {@code Package} of the given <a href="#binary-name">name</a> that
* has been defined by this class loader.
*
* @param name The <a href="#binary-name">package name</a>
*
* @return The {@code Package} of the given name that has been defined
* by this class loader, or {@code null} if not found
*
* @throws NullPointerException
* if {@code name} is {@code null}.
*
* @jvms 5.3 Run-time package
*
* @since 9
* @spec JPMS
*/
public final Package getDefinedPackage(String name) {
Objects.requireNonNull(name, "name cannot be null");
NamedPackage p = packages.get(name);
if (p == null)
return null;
return definePackage(name, p.module());
}
/**
* Returns all of the {@code Package}s that have been defined by
* this class loader. The returned array has no duplicated {@code Package}s
* of the same name.
*
* @apiNote This method returns an array rather than a {@code Set} or {@code Stream}
* for consistency with the existing {@link #getPackages} method.
*
* @return The array of {@code Package} objects that have been defined by
* this class loader; or an zero length array if no package has been
* defined by this class loader.
*
* @jvms 5.3 Run-time package
*
* @since 9
* @spec JPMS
*/
public final Package[] getDefinedPackages() {
return packages().toArray(Package[]::new);
}
/**
* Finds a package by <a href="#binary-name">name</a> in this class loader and its ancestors.
* <p>
* If this class loader defines a {@code Package} of the given name,
* the {@code Package} is returned. Otherwise, the ancestors of
* this class loader are searched recursively (parent by parent)
* for a {@code Package} of the given name.
*
* @apiNote The {@link #getPlatformClassLoader() platform class loader}
* may delegate to the application class loader but the application class
* loader is not its ancestor. When invoked on the platform class loader,
* this method will not find packages defined to the application
* class loader.
*
* @param name
* The <a href="#binary-name">package name</a>
*
* @return The {@code Package} of the given name that has been defined by
* this class loader or its ancestors, or {@code null} if not found.
*
* @throws NullPointerException
* if {@code name} is {@code null}.
*
* @deprecated
* If multiple class loaders delegate to each other and define classes
* with the same package name, and one such loader relies on the lookup
* behavior of {@code getPackage} to return a {@code Package} from
* a parent loader, then the properties exposed by the {@code Package}
* may not be as expected in the rest of the program.
* For example, the {@code Package} will only expose annotations from the
* {@code package-info.class} file defined by the parent loader, even if
* annotations exist in a {@code package-info.class} file defined by
* a child loader. A more robust approach is to use the
* {@link ClassLoader#getDefinedPackage} method which returns
* a {@code Package} for the specified class loader.
*
* @see ClassLoader#getDefinedPackage(String)
*
* @since 1.2
* @revised 9
* @spec JPMS
*/
@Deprecated(since="9")
protected Package getPackage(String name) {
Package pkg = getDefinedPackage(name);
if (pkg == null) {
if (parent != null) {
pkg = parent.getPackage(name);
} else {
pkg = BootLoader.getDefinedPackage(name);
}
}
return pkg;
}
/**
* Returns all of the {@code Package}s that have been defined by
* this class loader and its ancestors. The returned array may contain
* more than one {@code Package} object of the same package name, each
* defined by a different class loader in the class loader hierarchy.
*
* @apiNote The {@link #getPlatformClassLoader() platform class loader}
* may delegate to the application class loader. In other words,
* packages in modules defined to the application class loader may be
* visible to the platform class loader. On the other hand,
* the application class loader is not its ancestor and hence
* when invoked on the platform class loader, this method will not
* return any packages defined to the application class loader.
*
* @return The array of {@code Package} objects that have been defined by
* this class loader and its ancestors
*
* @see ClassLoader#getDefinedPackages()
*
* @since 1.2
* @revised 9
* @spec JPMS
*/
protected Package[] getPackages() {
Stream<Package> pkgs = packages();
ClassLoader ld = parent;
while (ld != null) {
pkgs = Stream.concat(ld.packages(), pkgs);
ld = ld.parent;
}
return Stream.concat(BootLoader.packages(), pkgs)
.toArray(Package[]::new);
}
// package-private
/**
* Returns a stream of Packages defined in this class loader
*/
Stream<Package> packages() {
return packages.values().stream()
.map(p -> definePackage(p.packageName(), p.module()));
}
// -- Native library access --
/**
* Returns the absolute path name of a native library. The VM invokes this
* method to locate the native libraries that belong to classes loaded with
* this class loader. If this method returns {@code null}, the VM
* searches the library along the path specified as the
* "{@code java.library.path}" property.
*
* @param libname
* The library name
*
* @return The absolute path of the native library
*
* @see System#loadLibrary(String)
* @see System#mapLibraryName(String)
*
* @since 1.2
*/
protected String findLibrary(String libname) {
return null;
}
/**
* The inner class NativeLibrary denotes a loaded native library instance.
* Every classloader contains a vector of loaded native libraries in the
* private field {@code nativeLibraries}. The native libraries loaded
* into the system are entered into the {@code systemNativeLibraries}
* vector.
*
* <p> Every native library requires a particular version of JNI. This is
* denoted by the private {@code jniVersion} field. This field is set by
* the VM when it loads the library, and used by the VM to pass the correct
* version of JNI to the native methods. </p>
*
* @see ClassLoader
* @since 1.2
*/
static class NativeLibrary {
// the class from which the library is loaded, also indicates
// the loader this native library belongs.
final Class<?> fromClass;
// the canonicalized name of the native library.
// or static library name
final String name;
// Indicates if the native library is linked into the VM
final boolean isBuiltin;
// opaque handle to native library, used in native code.
long handle;
// the version of JNI environment the native library requires.
int jniVersion;
native boolean load0(String name, boolean isBuiltin);
native long findEntry(String name);
NativeLibrary(Class<?> fromClass, String name, boolean isBuiltin) {
this.name = name;
this.fromClass = fromClass;
this.isBuiltin = isBuiltin;
}
/*
* Loads the native library and registers for cleanup when its
* associated class loader is unloaded
*/
boolean load() {
if (handle != 0) {
throw new InternalError("Native library " + name + " has been loaded");
}
if (!load0(name, isBuiltin)) return false;
// register the class loader for cleanup when unloaded
// built class loaders are never unloaded
ClassLoader loader = fromClass.getClassLoader();
if (loader != null &&
loader != getBuiltinPlatformClassLoader() &&
loader != getBuiltinAppClassLoader()) {
CleanerFactory.cleaner().register(loader,
new Unloader(name, handle, isBuiltin));
}
return true;
}
static boolean loadLibrary(Class<?> fromClass, String name, boolean isBuiltin) {
ClassLoader loader =
fromClass == null ? null : fromClass.getClassLoader();
synchronized (loadedLibraryNames) {
Map<String, NativeLibrary> libs =
loader != null ? loader.nativeLibraries() : systemNativeLibraries();
if (libs.containsKey(name)) {
return true;
}
if (loadedLibraryNames.contains(name)) {
throw new UnsatisfiedLinkError("Native Library " + name +
" already loaded in another classloader");
}
/*
* When a library is being loaded, JNI_OnLoad function can cause
* another loadLibrary invocation that should succeed.
*
* We use a static stack to hold the list of libraries we are
* loading because this can happen only when called by the
* same thread because Runtime.load and Runtime.loadLibrary
* are synchronous.
*
* If there is a pending load operation for the library, we
* immediately return success; otherwise, we raise
* UnsatisfiedLinkError.
*/
for (NativeLibrary lib : nativeLibraryContext) {
if (name.equals(lib.name)) {
if (loader == lib.fromClass.getClassLoader()) {
return true;
} else {
throw new UnsatisfiedLinkError("Native Library " +
name + " is being loaded in another classloader");
}
}
}
NativeLibrary lib = new NativeLibrary(fromClass, name, isBuiltin);
// load the native library
nativeLibraryContext.push(lib);
try {
if (!lib.load()) return false;
} finally {
nativeLibraryContext.pop();
}
// register the loaded native library
loadedLibraryNames.add(name);
libs.put(name, lib);
}
return true;
}
// Invoked in the VM to determine the context class in JNI_OnLoad
// and JNI_OnUnload
static Class<?> getFromClass() {
return nativeLibraryContext.peek().fromClass;
}
// native libraries being loaded
static Deque<NativeLibrary> nativeLibraryContext = new ArrayDeque<>(8);
/*
* The run() method will be invoked when this class loader becomes
* phantom reachable to unload the native library.
*/
static class Unloader implements Runnable {
// This represents the context when a native library is unloaded
// and getFromClass() will return null,
static final NativeLibrary UNLOADER =
new NativeLibrary(null, "dummy", false);
final String name;
final long handle;
final boolean isBuiltin;
Unloader(String name, long handle, boolean isBuiltin) {
if (handle == 0) {
throw new IllegalArgumentException(
"Invalid handle for native library " + name);
}
this.name = name;
this.handle = handle;
this.isBuiltin = isBuiltin;
}
@Override
public void run() {
synchronized (loadedLibraryNames) {
/* remove the native library name */
loadedLibraryNames.remove(name);
nativeLibraryContext.push(UNLOADER);
try {
unload(name, isBuiltin, handle);
} finally {
nativeLibraryContext.pop();
}
}
}
}
// JNI FindClass expects the caller class if invoked from JNI_OnLoad
// and JNI_OnUnload is NativeLibrary class
static native void unload(String name, boolean isBuiltin, long handle);
}
// The paths searched for libraries
private static String usr_paths[];
private static String sys_paths[];
private static String[] initializePath(String propName) {
String ldPath = System.getProperty(propName, "");
int ldLen = ldPath.length();
char ps = File.pathSeparatorChar;
int psCount = 0;
if (ClassLoaderHelper.allowsQuotedPathElements &&
ldPath.indexOf('\"') >= 0) {
// First, remove quotes put around quoted parts of paths.
// Second, use a quotation mark as a new path separator.
// This will preserve any quoted old path separators.
char[] buf = new char[ldLen];
int bufLen = 0;
for (int i = 0; i < ldLen; ++i) {
char ch = ldPath.charAt(i);
if (ch == '\"') {
while (++i < ldLen &&
(ch = ldPath.charAt(i)) != '\"') {
buf[bufLen++] = ch;
}
} else {
if (ch == ps) {
psCount++;
ch = '\"';
}
buf[bufLen++] = ch;
}
}
ldPath = new String(buf, 0, bufLen);
ldLen = bufLen;
ps = '\"';
} else {
for (int i = ldPath.indexOf(ps); i >= 0;
i = ldPath.indexOf(ps, i + 1)) {
psCount++;
}
}
String[] paths = new String[psCount + 1];
int pathStart = 0;
for (int j = 0; j < psCount; ++j) {
int pathEnd = ldPath.indexOf(ps, pathStart);
paths[j] = (pathStart < pathEnd) ?
ldPath.substring(pathStart, pathEnd) : ".";
pathStart = pathEnd + 1;
}
paths[psCount] = (pathStart < ldLen) ?
ldPath.substring(pathStart, ldLen) : ".";
return paths;
}
// Invoked in the java.lang.Runtime class to implement load and loadLibrary.
static void loadLibrary(Class<?> fromClass, String name,
boolean isAbsolute) {
ClassLoader loader =
(fromClass == null) ? null : fromClass.getClassLoader();
if (sys_paths == null) {
usr_paths = initializePath("java.library.path");
sys_paths = initializePath("sun.boot.library.path");
}
if (isAbsolute) {
if (loadLibrary0(fromClass, new File(name))) {
return;
}
throw new UnsatisfiedLinkError("Can't load library: " + name);
}
if (loader != null) {
String libfilename = loader.findLibrary(name);
if (libfilename != null) {
File libfile = new File(libfilename);
if (!libfile.isAbsolute()) {
throw new UnsatisfiedLinkError(
"ClassLoader.findLibrary failed to return an absolute path: " + libfilename);
}
if (loadLibrary0(fromClass, libfile)) {
return;
}
throw new UnsatisfiedLinkError("Can't load " + libfilename);
}
}
for (String sys_path : sys_paths) {
File libfile = new File(sys_path, System.mapLibraryName(name));
if (loadLibrary0(fromClass, libfile)) {
return;
}
libfile = ClassLoaderHelper.mapAlternativeName(libfile);
if (libfile != null && loadLibrary0(fromClass, libfile)) {
return;
}
}
if (loader != null) {
for (String usr_path : usr_paths) {
File libfile = new File(usr_path, System.mapLibraryName(name));
if (loadLibrary0(fromClass, libfile)) {
return;
}
libfile = ClassLoaderHelper.mapAlternativeName(libfile);
if (libfile != null && loadLibrary0(fromClass, libfile)) {
return;
}
}
}
// Oops, it failed
throw new UnsatisfiedLinkError("no " + name +
" in java.library.path: " + Arrays.toString(usr_paths));
}
private static native String findBuiltinLib(String name);
private static boolean loadLibrary0(Class<?> fromClass, final File file) {
// Check to see if we're attempting to access a static library
String name = findBuiltinLib(file.getName());
boolean isBuiltin = (name != null);
if (!isBuiltin) {
name = AccessController.doPrivileged(
new PrivilegedAction<>() {
public String run() {
try {
return file.exists() ? file.getCanonicalPath() : null;
} catch (IOException e) {
return null;
}
}
});
if (name == null) {
return false;
}
}
return NativeLibrary.loadLibrary(fromClass, name, isBuiltin);
}
/*
* Invoked in the VM class linking code.
*/
private static long findNative(ClassLoader loader, String entryName) {
Map<String, NativeLibrary> libs =
loader != null ? loader.nativeLibraries() : systemNativeLibraries();
if (libs.isEmpty())
return 0;
// the native libraries map may be updated in another thread
// when a native library is being loaded. No symbol will be
// searched from it yet.
for (NativeLibrary lib : libs.values()) {
long entry = lib.findEntry(entryName);
if (entry != 0) return entry;
}
return 0;
}
// All native library names we've loaded.
// This also serves as the lock to obtain nativeLibraries
// and write to nativeLibraryContext.
private static final Set<String> loadedLibraryNames = new HashSet<>();
// Native libraries belonging to system classes.
private static volatile Map<String, NativeLibrary> systemNativeLibraries;
// Native libraries associated with the class loader.
private volatile Map<String, NativeLibrary> nativeLibraries;
/*
* Returns the native libraries map associated with bootstrap class loader
* This method will create the map at the first time when called.
*/
private static Map<String, NativeLibrary> systemNativeLibraries() {
Map<String, NativeLibrary> libs = systemNativeLibraries;
if (libs == null) {
synchronized (loadedLibraryNames) {
libs = systemNativeLibraries;
if (libs == null) {
libs = systemNativeLibraries = new ConcurrentHashMap<>();
}
}
}
return libs;
}
/*
* Returns the native libraries map associated with this class loader
* This method will create the map at the first time when called.
*/
private Map<String, NativeLibrary> nativeLibraries() {
Map<String, NativeLibrary> libs = nativeLibraries;
if (libs == null) {
synchronized (loadedLibraryNames) {
libs = nativeLibraries;
if (libs == null) {
libs = nativeLibraries = new ConcurrentHashMap<>();
}
}
}
return libs;
}
// -- Assertion management --
final Object assertionLock;
// The default toggle for assertion checking.
// @GuardedBy("assertionLock")
private boolean defaultAssertionStatus = false;
// Maps String packageName to Boolean package default assertion status Note
// that the default package is placed under a null map key. If this field
// is null then we are delegating assertion status queries to the VM, i.e.,
// none of this ClassLoader's assertion status modification methods have
// been invoked.
// @GuardedBy("assertionLock")
private Map<String, Boolean> packageAssertionStatus = null;
// Maps String fullyQualifiedClassName to Boolean assertionStatus If this
// field is null then we are delegating assertion status queries to the VM,
// i.e., none of this ClassLoader's assertion status modification methods
// have been invoked.
// @GuardedBy("assertionLock")
Map<String, Boolean> classAssertionStatus = null;
/**
* Sets the default assertion status for this class loader. This setting
* determines whether classes loaded by this class loader and initialized
* in the future will have assertions enabled or disabled by default.
* This setting may be overridden on a per-package or per-class basis by
* invoking {@link #setPackageAssertionStatus(String, boolean)} or {@link
* #setClassAssertionStatus(String, boolean)}.
*
* @param enabled
* {@code true} if classes loaded by this class loader will
* henceforth have assertions enabled by default, {@code false}
* if they will have assertions disabled by default.
*
* @since 1.4
*/
public void setDefaultAssertionStatus(boolean enabled) {
synchronized (assertionLock) {
if (classAssertionStatus == null)
initializeJavaAssertionMaps();
defaultAssertionStatus = enabled;
}
}
/**
* Sets the package default assertion status for the named package. The
* package default assertion status determines the assertion status for
* classes initialized in the future that belong to the named package or
* any of its "subpackages".
*
* <p> A subpackage of a package named p is any package whose name begins
* with "{@code p.}". For example, {@code javax.swing.text} is a
* subpackage of {@code javax.swing}, and both {@code java.util} and
* {@code java.lang.reflect} are subpackages of {@code java}.
*
* <p> In the event that multiple package defaults apply to a given class,
* the package default pertaining to the most specific package takes
* precedence over the others. For example, if {@code javax.lang} and
* {@code javax.lang.reflect} both have package defaults associated with
* them, the latter package default applies to classes in
* {@code javax.lang.reflect}.
*
* <p> Package defaults take precedence over the class loader's default
* assertion status, and may be overridden on a per-class basis by invoking
* {@link #setClassAssertionStatus(String, boolean)}. </p>
*
* @param packageName
* The name of the package whose package default assertion status
* is to be set. A {@code null} value indicates the unnamed
* package that is "current"
* (see section 7.4.2 of
* <cite>The Java™ Language Specification</cite>.)
*
* @param enabled
* {@code true} if classes loaded by this classloader and
* belonging to the named package or any of its subpackages will
* have assertions enabled by default, {@code false} if they will
* have assertions disabled by default.
*
* @since 1.4
*/
public void setPackageAssertionStatus(String packageName,
boolean enabled) {
synchronized (assertionLock) {
if (packageAssertionStatus == null)
initializeJavaAssertionMaps();
packageAssertionStatus.put(packageName, enabled);
}
}
/**
* Sets the desired assertion status for the named top-level class in this
* class loader and any nested classes contained therein. This setting
* takes precedence over the class loader's default assertion status, and
* over any applicable per-package default. This method has no effect if
* the named class has already been initialized. (Once a class is
* initialized, its assertion status cannot change.)
*
* <p> If the named class is not a top-level class, this invocation will
* have no effect on the actual assertion status of any class. </p>
*
* @param className
* The fully qualified class name of the top-level class whose
* assertion status is to be set.
*
* @param enabled
* {@code true} if the named class is to have assertions
* enabled when (and if) it is initialized, {@code false} if the
* class is to have assertions disabled.
*
* @since 1.4
*/
public void setClassAssertionStatus(String className, boolean enabled) {
synchronized (assertionLock) {
if (classAssertionStatus == null)
initializeJavaAssertionMaps();
classAssertionStatus.put(className, enabled);
}
}
/**
* Sets the default assertion status for this class loader to
* {@code false} and discards any package defaults or class assertion
* status settings associated with the class loader. This method is
* provided so that class loaders can be made to ignore any command line or
* persistent assertion status settings and "start with a clean slate."
*
* @since 1.4
*/
public void clearAssertionStatus() {
/*
* Whether or not "Java assertion maps" are initialized, set
* them to empty maps, effectively ignoring any present settings.
*/
synchronized (assertionLock) {
classAssertionStatus = new HashMap<>();
packageAssertionStatus = new HashMap<>();
defaultAssertionStatus = false;
}
}
/**
* Returns the assertion status that would be assigned to the specified
* class if it were to be initialized at the time this method is invoked.
* If the named class has had its assertion status set, the most recent
* setting will be returned; otherwise, if any package default assertion
* status pertains to this class, the most recent setting for the most
* specific pertinent package default assertion status is returned;
* otherwise, this class loader's default assertion status is returned.
* </p>
*
* @param className
* The fully qualified class name of the class whose desired
* assertion status is being queried.
*
* @return The desired assertion status of the specified class.
*
* @see #setClassAssertionStatus(String, boolean)
* @see #setPackageAssertionStatus(String, boolean)
* @see #setDefaultAssertionStatus(boolean)
*
* @since 1.4
*/
boolean desiredAssertionStatus(String className) {
synchronized (assertionLock) {
// assert classAssertionStatus != null;
// assert packageAssertionStatus != null;
// Check for a class entry
Boolean result = classAssertionStatus.get(className);
if (result != null)
return result.booleanValue();
// Check for most specific package entry
int dotIndex = className.lastIndexOf('.');
if (dotIndex < 0) { // default package
result = packageAssertionStatus.get(null);
if (result != null)
return result.booleanValue();
}
while(dotIndex > 0) {
className = className.substring(0, dotIndex);
result = packageAssertionStatus.get(className);
if (result != null)
return result.booleanValue();
dotIndex = className.lastIndexOf('.', dotIndex-1);
}
// Return the classloader default
return defaultAssertionStatus;
}
}
// Set up the assertions with information provided by the VM.
// Note: Should only be called inside a synchronized block
private void initializeJavaAssertionMaps() {
// assert Thread.holdsLock(assertionLock);
classAssertionStatus = new HashMap<>();
packageAssertionStatus = new HashMap<>();
AssertionStatusDirectives directives = retrieveDirectives();
for(int i = 0; i < directives.classes.length; i++)
classAssertionStatus.put(directives.classes[i],
directives.classEnabled[i]);
for(int i = 0; i < directives.packages.length; i++)
packageAssertionStatus.put(directives.packages[i],
directives.packageEnabled[i]);
defaultAssertionStatus = directives.deflt;
}
// Retrieves the assertion directives from the VM.
private static native AssertionStatusDirectives retrieveDirectives();
// -- Misc --
/**
* Returns the ConcurrentHashMap used as a storage for ClassLoaderValue(s)
* associated with this ClassLoader, creating it if it doesn't already exist.
*/
ConcurrentHashMap<?, ?> createOrGetClassLoaderValueMap() {
ConcurrentHashMap<?, ?> map = classLoaderValueMap;
if (map == null) {
map = new ConcurrentHashMap<>();
boolean set = trySetObjectField("classLoaderValueMap", map);
if (!set) {
// beaten by someone else
map = classLoaderValueMap;
}
}
return map;
}
// the storage for ClassLoaderValue(s) associated with this ClassLoader
private volatile ConcurrentHashMap<?, ?> classLoaderValueMap;
/**
* Attempts to atomically set a volatile field in this object. Returns
* {@code true} if not beaten by another thread. Avoids the use of
* AtomicReferenceFieldUpdater in this class.
*/
private boolean trySetObjectField(String name, Object obj) {
Unsafe unsafe = Unsafe.getUnsafe();
Class<?> k = ClassLoader.class;
long offset;
offset = unsafe.objectFieldOffset(k, name);
return unsafe.compareAndSetObject(this, offset, null, obj);
}
}
/*
* A utility class that will enumerate over an array of enumerations.
*/
final class CompoundEnumeration<E> implements Enumeration<E> {
private final Enumeration<E>[] enums;
private int index;
public CompoundEnumeration(Enumeration<E>[] enums) {
this.enums = enums;
}
private boolean next() {
while (index < enums.length) {
if (enums[index] != null && enums[index].hasMoreElements()) {
return true;
}
index++;
}
return false;
}
public boolean hasMoreElements() {
return next();
}
public E nextElement() {
if (!next()) {
throw new NoSuchElementException();
}
return enums[index].nextElement();
}
}
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