Jackson Data Binding Source Code
Jackson is "the Java JSON library" or "the best JSON parser for Java". Or simply as "JSON for Java".
Jackson Databind Source Code files are provided in the source packge (jackson-databind-2.14.0-sources.jar). You can download it at Jackson Maven Website.
You can also browse Jackson Databind Source Code below:
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⏎ com/fasterxml/jackson/databind/deser/DeserializerCache.java
package com.fasterxml.jackson.databind.deser;
import java.util.HashMap;
import com.fasterxml.jackson.annotation.JsonFormat;
import com.fasterxml.jackson.databind.*;
import com.fasterxml.jackson.databind.deser.std.StdDelegatingDeserializer;
import com.fasterxml.jackson.databind.introspect.Annotated;
import com.fasterxml.jackson.databind.type.*;
import com.fasterxml.jackson.databind.util.ClassUtil;
import com.fasterxml.jackson.databind.util.Converter;
import com.fasterxml.jackson.databind.util.LRUMap;
/**
* Class that defines caching layer between callers (like
* {@link ObjectMapper},
* {@link com.fasterxml.jackson.databind.DeserializationContext})
* and classes that construct deserializers
* ({@link com.fasterxml.jackson.databind.deser.DeserializerFactory}).
*/
public final class DeserializerCache
implements java.io.Serializable // since 2.1
{
private static final long serialVersionUID = 1L;
/*
/**********************************************************
/* Caching
/**********************************************************
*/
/**
* We will also cache some dynamically constructed deserializers;
* specifically, ones that are expensive to construct.
* This currently means bean, Enum and container deserializers.
*/
final protected LRUMap<JavaType, JsonDeserializer<Object>> _cachedDeserializers;
/**
* During deserializer construction process we may need to keep track of partially
* completed deserializers, to resolve cyclic dependencies. This is the
* map used for storing deserializers before they are fully complete.
*/
final protected HashMap<JavaType, JsonDeserializer<Object>> _incompleteDeserializers
= new HashMap<JavaType, JsonDeserializer<Object>>(8);
/*
/**********************************************************
/* Life-cycle
/**********************************************************
*/
public DeserializerCache() {
this(2000); // see [databind#1995]
}
public DeserializerCache(int maxSize) {
int initial = Math.min(64, maxSize>>2);
_cachedDeserializers = new LRUMap<>(initial, maxSize);
}
/*
/**********************************************************
/* JDK serialization handling
/**********************************************************
*/
Object writeReplace() {
// instead of making this transient, just clear it:
_incompleteDeserializers.clear();
return this;
}
/*
/**********************************************************
/* Access to caching aspects
/**********************************************************
*/
/**
* Method that can be used to determine how many deserializers this
* provider is caching currently
* (if it does caching: default implementation does)
* Exact count depends on what kind of deserializers get cached;
* default implementation caches only dynamically constructed deserializers,
* but not eagerly constructed standard deserializers (which is different
* from how serializer provider works).
*<p>
* The main use case for this method is to allow conditional flushing of
* deserializer cache, if certain number of entries is reached.
*/
public int cachedDeserializersCount() {
return _cachedDeserializers.size();
}
/**
* Method that will drop all dynamically constructed deserializers (ones that
* are counted as result value for {@link #cachedDeserializersCount}).
* This can be used to remove memory usage (in case some deserializers are
* only used once or so), or to force re-construction of deserializers after
* configuration changes for mapper than owns the provider.
*/
public void flushCachedDeserializers() {
_cachedDeserializers.clear();
}
/*
/**********************************************************
/* General deserializer locating method
/**********************************************************
*/
/**
* Method called to get hold of a deserializer for a value of given type;
* or if no such deserializer can be found, a default handler (which
* may do a best-effort generic serialization or just simply
* throw an exception when invoked).
*<p>
* Note: this method is only called for value types; not for keys.
* Key deserializers can be accessed using {@link #findKeyDeserializer}.
*<p>
* Note also that deserializer returned is guaranteed to be resolved
* (if it is of type {@link ResolvableDeserializer}), but
* not contextualized (wrt {@link ContextualDeserializer}): caller
* has to handle latter if necessary.
*
* @param ctxt Deserialization context
* @param propertyType Declared type of the value to deserializer (obtained using
* 'setter' method signature and/or type annotations
*
* @throws JsonMappingException if there are fatal problems with
* accessing suitable deserializer; including that of not
* finding any serializer
*/
public JsonDeserializer<Object> findValueDeserializer(DeserializationContext ctxt,
DeserializerFactory factory, JavaType propertyType)
throws JsonMappingException
{
JsonDeserializer<Object> deser = _findCachedDeserializer(propertyType);
if (deser == null) {
// If not, need to request factory to construct (or recycle)
deser = _createAndCacheValueDeserializer(ctxt, factory, propertyType);
if (deser == null) {
/* Should we let caller handle it? Let's have a helper method
* decide it; can throw an exception, or return a valid
* deserializer
*/
deser = _handleUnknownValueDeserializer(ctxt, propertyType);
}
}
return deser;
}
/**
* Method called to get hold of a deserializer to use for deserializing
* keys for {@link java.util.Map}.
*
* @throws JsonMappingException if there are fatal problems with
* accessing suitable key deserializer; including that of not
* finding any serializer
*/
public KeyDeserializer findKeyDeserializer(DeserializationContext ctxt,
DeserializerFactory factory, JavaType type)
throws JsonMappingException
{
KeyDeserializer kd = factory.createKeyDeserializer(ctxt, type);
if (kd == null) { // if none found, need to use a placeholder that'll fail
return _handleUnknownKeyDeserializer(ctxt, type);
}
// First: need to resolve?
if (kd instanceof ResolvableDeserializer) {
((ResolvableDeserializer) kd).resolve(ctxt);
}
return kd;
}
/**
* Method called to find out whether provider would be able to find
* a deserializer for given type, using a root reference (i.e. not
* through fields or membership in an array or collection)
*/
public boolean hasValueDeserializerFor(DeserializationContext ctxt,
DeserializerFactory factory, JavaType type)
throws JsonMappingException
{
/* Note: mostly copied from findValueDeserializer, except for
* handling of unknown types
*/
JsonDeserializer<Object> deser = _findCachedDeserializer(type);
if (deser == null) {
deser = _createAndCacheValueDeserializer(ctxt, factory, type);
}
return (deser != null);
}
/*
/**********************************************************
/* Helper methods that handle cache lookups
/**********************************************************
*/
protected JsonDeserializer<Object> _findCachedDeserializer(JavaType type)
{
if (type == null) {
throw new IllegalArgumentException("Null JavaType passed");
}
if (_hasCustomHandlers(type)) {
return null;
}
return _cachedDeserializers.get(type);
}
/**
* Method that will try to create a deserializer for given type,
* and resolve and cache it if necessary
*
* @param ctxt Currently active deserialization context
* @param type Type of property to deserialize
*/
protected JsonDeserializer<Object> _createAndCacheValueDeserializer(DeserializationContext ctxt,
DeserializerFactory factory, JavaType type)
throws JsonMappingException
{
/* Only one thread to construct deserializers at any given point in time;
* limitations necessary to ensure that only completely initialized ones
* are visible and used.
*/
synchronized (_incompleteDeserializers) {
// Ok, then: could it be that due to a race condition, deserializer can now be found?
JsonDeserializer<Object> deser = _findCachedDeserializer(type);
if (deser != null) {
return deser;
}
int count = _incompleteDeserializers.size();
// Or perhaps being resolved right now?
if (count > 0) {
deser = _incompleteDeserializers.get(type);
if (deser != null) {
return deser;
}
}
// Nope: need to create and possibly cache
try {
return _createAndCache2(ctxt, factory, type);
} finally {
// also: any deserializers that have been created are complete by now
if (count == 0 && _incompleteDeserializers.size() > 0) {
_incompleteDeserializers.clear();
}
}
}
}
/**
* Method that handles actual construction (via factory) and caching (both
* intermediate and eventual)
*/
protected JsonDeserializer<Object> _createAndCache2(DeserializationContext ctxt,
DeserializerFactory factory, JavaType type)
throws JsonMappingException
{
JsonDeserializer<Object> deser;
try {
deser = _createDeserializer(ctxt, factory, type);
} catch (IllegalArgumentException iae) {
// We better only expose checked exceptions, since those
// are what caller is expected to handle
ctxt.reportBadDefinition(type, ClassUtil.exceptionMessage(iae));
deser = null; // never gets here
}
if (deser == null) {
return null;
}
/* cache resulting deserializer? always true for "plain" BeanDeserializer
* (but can be re-defined for sub-classes by using @JsonCachable!)
*/
// 27-Mar-2015, tatu: As per [databind#735], avoid caching types with custom value desers
boolean addToCache = !_hasCustomHandlers(type) && deser.isCachable();
/* we will temporarily hold on to all created deserializers (to
* handle cyclic references, and possibly reuse non-cached
* deserializers (list, map))
*/
/* 07-Jun-2010, tatu: Danger: [JACKSON-296] was caused by accidental
* resolution of a reference -- couple of ways to prevent this;
* either not add Lists or Maps, or clear references eagerly.
* Let's actually do both; since both seem reasonable.
*/
/* Need to resolve? Mostly done for bean deserializers; required for
* resolving cyclic references.
*/
if (deser instanceof ResolvableDeserializer) {
_incompleteDeserializers.put(type, deser);
((ResolvableDeserializer)deser).resolve(ctxt);
_incompleteDeserializers.remove(type);
}
if (addToCache) {
_cachedDeserializers.put(type, deser);
}
return deser;
}
/*
/**********************************************************
/* Helper methods for actual construction of deserializers
/**********************************************************
*/
/**
* Method that does the heavy lifting of checking for per-type annotations,
* find out full type, and figure out which actual factory method
* to call.
*/
@SuppressWarnings("unchecked")
protected JsonDeserializer<Object> _createDeserializer(DeserializationContext ctxt,
DeserializerFactory factory, JavaType type)
throws JsonMappingException
{
final DeserializationConfig config = ctxt.getConfig();
// First things first: do we need to use abstract type mapping?
if (type.isAbstract() || type.isMapLikeType() || type.isCollectionLikeType()) {
type = factory.mapAbstractType(config, type);
}
BeanDescription beanDesc = config.introspect(type);
// Then: does type define explicit deserializer to use, with annotation(s)?
JsonDeserializer<Object> deser = findDeserializerFromAnnotation(ctxt,
beanDesc.getClassInfo());
if (deser != null) {
return deser;
}
// If not, may have further type-modification annotations to check:
JavaType newType = modifyTypeByAnnotation(ctxt, beanDesc.getClassInfo(), type);
if (newType != type) {
type = newType;
beanDesc = config.introspect(newType);
}
// We may also have a Builder type to consider...
Class<?> builder = beanDesc.findPOJOBuilder();
if (builder != null) {
return (JsonDeserializer<Object>) factory.createBuilderBasedDeserializer(
ctxt, type, beanDesc, builder);
}
// Or perhaps a Converter?
Converter<Object,Object> conv = beanDesc.findDeserializationConverter();
if (conv == null) { // nope, just construct in normal way
return (JsonDeserializer<Object>) _createDeserializer2(ctxt, factory, type, beanDesc);
}
// otherwise need to do bit of introspection
JavaType delegateType = conv.getInputType(ctxt.getTypeFactory());
// One more twist, as per [databind#288]; probably need to get new BeanDesc
if (!delegateType.hasRawClass(type.getRawClass())) {
beanDesc = config.introspect(delegateType);
}
return new StdDelegatingDeserializer<Object>(conv, delegateType,
_createDeserializer2(ctxt, factory, delegateType, beanDesc));
}
protected JsonDeserializer<?> _createDeserializer2(DeserializationContext ctxt,
DeserializerFactory factory, JavaType type, BeanDescription beanDesc)
throws JsonMappingException
{
final DeserializationConfig config = ctxt.getConfig();
// If not, let's see which factory method to use
// 12-Feb-20202, tatu: Need to ensure that not only all Enum implementations get
// there, but also `Enum` -- latter wrt [databind#2605], polymorphic usage
if (type.isEnumType()) {
return factory.createEnumDeserializer(ctxt, type, beanDesc);
}
if (type.isContainerType()) {
if (type.isArrayType()) {
return factory.createArrayDeserializer(ctxt, (ArrayType) type, beanDesc);
}
if (type.isMapLikeType()) {
// 11-Mar-2017, tatu: As per [databind#1554], also need to block
// handling as Map if overriden with "as POJO" option.
// Ideally we'd determine it bit later on (to allow custom handler checks)
// but that won't work for other reasons. So do it here.
// (read: rewrite for 3.0)
JsonFormat.Value format = beanDesc.findExpectedFormat(null);
if (format.getShape() != JsonFormat.Shape.OBJECT) {
MapLikeType mlt = (MapLikeType) type;
if (mlt instanceof MapType) {
return factory.createMapDeserializer(ctxt,(MapType) mlt, beanDesc);
}
return factory.createMapLikeDeserializer(ctxt, mlt, beanDesc);
}
}
if (type.isCollectionLikeType()) {
/* 03-Aug-2012, tatu: As per [databind#40], one exception is if shape
* is to be Shape.OBJECT. Ideally we'd determine it bit later on
* (to allow custom handler checks), but that won't work for other
* reasons. So do it here.
*/
JsonFormat.Value format = beanDesc.findExpectedFormat(null);
if (format.getShape() != JsonFormat.Shape.OBJECT) {
CollectionLikeType clt = (CollectionLikeType) type;
if (clt instanceof CollectionType) {
return factory.createCollectionDeserializer(ctxt, (CollectionType) clt, beanDesc);
}
return factory.createCollectionLikeDeserializer(ctxt, clt, beanDesc);
}
}
}
if (type.isReferenceType()) {
return factory.createReferenceDeserializer(ctxt, (ReferenceType) type, beanDesc);
}
if (JsonNode.class.isAssignableFrom(type.getRawClass())) {
return factory.createTreeDeserializer(config, type, beanDesc);
}
return factory.createBeanDeserializer(ctxt, type, beanDesc);
}
/**
* Helper method called to check if a class or method
* has annotation that tells which class to use for deserialization.
* Returns null if no such annotation found.
*/
protected JsonDeserializer<Object> findDeserializerFromAnnotation(DeserializationContext ctxt,
Annotated ann)
throws JsonMappingException
{
Object deserDef = ctxt.getAnnotationIntrospector().findDeserializer(ann);
if (deserDef == null) {
return null;
}
JsonDeserializer<Object> deser = ctxt.deserializerInstance(ann, deserDef);
// One more thing however: may need to also apply a converter:
return findConvertingDeserializer(ctxt, ann, deser);
}
/**
* Helper method that will check whether given annotated entity (usually class,
* but may also be a property accessor) indicates that a {@link Converter} is to
* be used; and if so, to construct and return suitable serializer for it.
* If not, will simply return given serializer as is.
*/
protected JsonDeserializer<Object> findConvertingDeserializer(DeserializationContext ctxt,
Annotated a, JsonDeserializer<Object> deser)
throws JsonMappingException
{
Converter<Object,Object> conv = findConverter(ctxt, a);
if (conv == null) {
return deser;
}
JavaType delegateType = conv.getInputType(ctxt.getTypeFactory());
return (JsonDeserializer<Object>) new StdDelegatingDeserializer<Object>(conv, delegateType, deser);
}
protected Converter<Object,Object> findConverter(DeserializationContext ctxt,
Annotated a)
throws JsonMappingException
{
Object convDef = ctxt.getAnnotationIntrospector().findDeserializationConverter(a);
if (convDef == null) {
return null;
}
return ctxt.converterInstance(a, convDef);
}
/**
* Method called to see if given method has annotations that indicate
* a more specific type than what the argument specifies.
* If annotations are present, they must specify compatible Class;
* instance of which can be assigned using the method. This means
* that the Class has to be raw class of type, or its sub-class
* (or, implementing class if original Class instance is an interface).
*
* @param a Method or field that the type is associated with
* @param type Type derived from the setter argument
*
* @return Original type if no annotations are present; or a more
* specific type derived from it if type annotation(s) was found
*
* @throws JsonMappingException if invalid annotation is found
*/
private JavaType modifyTypeByAnnotation(DeserializationContext ctxt,
Annotated a, JavaType type)
throws JsonMappingException
{
AnnotationIntrospector intr = ctxt.getAnnotationIntrospector();
if (intr == null) {
return type;
}
// First things first: find explicitly annotated deserializer(s)
// then key/value handlers (annotated deserializers)?
if (type.isMapLikeType()) {
JavaType keyType = type.getKeyType();
// 21-Mar-2011, tatu: ... and associated deserializer too (unless already assigned)
// (not 100% why or how, but this does seem to get called more than once, which
// is not good: for now, let's just avoid errors)
if (keyType != null && keyType.getValueHandler() == null) {
Object kdDef = intr.findKeyDeserializer(a);
if (kdDef != null) {
KeyDeserializer kd = ctxt.keyDeserializerInstance(a, kdDef);
if (kd != null) {
type = ((MapLikeType) type).withKeyValueHandler(kd);
// keyType = type.getKeyType(); // just in case it's used below
}
}
}
}
JavaType contentType = type.getContentType();
if (contentType != null) {
if (contentType.getValueHandler() == null) { // as with above, avoid resetting (which would trigger exception)
Object cdDef = intr.findContentDeserializer(a);
if (cdDef != null) {
JsonDeserializer<?> cd = null;
if (cdDef instanceof JsonDeserializer<?>) {
cd = (JsonDeserializer<?>) cdDef;
} else {
Class<?> cdClass = _verifyAsClass(cdDef, "findContentDeserializer", JsonDeserializer.None.class);
if (cdClass != null) {
cd = ctxt.deserializerInstance(a, cdClass);
}
}
if (cd != null) {
type = type.withContentValueHandler(cd);
}
}
}
}
// And after handlers, possible type refinements
// (note: could possibly avoid this if explicit deserializer was invoked?)
type = intr.refineDeserializationType(ctxt.getConfig(), a, type);
return type;
}
/*
/**********************************************************
/* Helper methods, other
/**********************************************************
*/
/**
* Helper method used to prevent both caching and cache lookups for structured
* types that have custom value handlers
*
* @since 2.8.11
*/
private boolean _hasCustomHandlers(JavaType t) {
if (t.isContainerType()) {
// First: value types may have both value and type handlers
JavaType ct = t.getContentType();
if (ct != null) {
if ((ct.getValueHandler() != null) || (ct.getTypeHandler() != null)) {
return true;
}
}
// Second: map(-like) types may have value handler for key (but not type; keys are untyped)
if (t.isMapLikeType()) {
JavaType kt = t.getKeyType();
if (kt.getValueHandler() != null) {
return true;
}
}
}
return false;
}
private Class<?> _verifyAsClass(Object src, String methodName, Class<?> noneClass)
{
if (src == null) {
return null;
}
if (!(src instanceof Class)) {
throw new IllegalStateException("AnnotationIntrospector."+methodName+"() returned value of type "+src.getClass().getName()+": expected type JsonSerializer or Class<JsonSerializer> instead");
}
Class<?> cls = (Class<?>) src;
if (cls == noneClass || ClassUtil.isBogusClass(cls)) {
return null;
}
return cls;
}
/*
/**********************************************************
/* Overridable error reporting methods
/**********************************************************
*/
protected JsonDeserializer<Object> _handleUnknownValueDeserializer(DeserializationContext ctxt, JavaType type)
throws JsonMappingException
{
// Let's try to figure out the reason, to give better error messages
Class<?> rawClass = type.getRawClass();
if (!ClassUtil.isConcrete(rawClass)) {
return ctxt.reportBadDefinition(type, "Cannot find a Value deserializer for abstract type "+type);
}
return ctxt.reportBadDefinition(type, "Cannot find a Value deserializer for type "+type);
}
protected KeyDeserializer _handleUnknownKeyDeserializer(DeserializationContext ctxt, JavaType type)
throws JsonMappingException
{
return ctxt.reportBadDefinition(type, "Cannot find a (Map) Key deserializer for type "+type);
}
}
⏎ com/fasterxml/jackson/databind/deser/DeserializerCache.java
Or download all of them as a single archive file:
File name: jackson-databind-2.14.0-sources.jar File size: 1187952 bytes Release date: 2022-11-05 Download
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