The Proxy design pattern allows you to provide "a surrogate or placeholder for another object to control access to it". Proxies can be used in many ways. Some of which are:

• Deferred Initialization - the proxy acts as a "stand-in" for the actual implementation allowing it to be instantiated only when absolutely necessary.
• Security - the proxy object can verify that the user actually has the permission to execute the method (a la EJB).
• Logging - the proxy can log evey method invocation, providing valuable debugging information.
• Performance Monitoring - the proxy can log each method invocation to a performance monitor allowing system administrators to see what parts of the system are potentially bogged down.

Commons Proxy supports dynamic proxy generation using proxy factories, object providers, invokers, and interceptors.

JAR File Size and Download Location:

File name: commons-proxy.jar, commons-proxy-1.0.jar
File size: 73169 bytes
Date modified: 23-Feb-2008
Download: Apche Commons Proxy

Manifest of the JAR:

Implementation-Title: Commons Proxy
Built-By: jcarman
Tool: Bnd-0.0.238
Implementation-Vendor: The Apache Software Foundation
Implementation-Vendor-Id: org.apache
Specification-Title: Commons Proxy
Bundle-License: http://www.apache.org/licenses/LICENSE-2.0.txt
Bundle-SymbolicName: org.apache.commons.proxy
X-Compile-Target-JDK: 1.4
Implementation-Version: 1.0
Specification-Vendor: The Apache Software Foundation
Bundle-Name: Commons Proxy
X-Compile-Source-JDK: 1.4
Bundle-Vendor: The Apache Software Foundation
Bundle-Version: 1.0
Build-Jdk: 1.6.0
Bnd-LastModified: 1203784860698
Bundle-ManifestVersion: 2
Bundle-Description: Java library for dynamic proxying
Bundle-DocURL: http://www.apache.org/
Import-Package: EDU.oswego.cs.dl.util.concurrent,com.caucho.burlap.cli
 ent,com.caucho.hessian.client,javassist,java

List of Classes in the JAR:

org/apache/commons/proxy/Interceptor
org/apache/commons/proxy/Invocation
org/apache/commons/proxy/Invoker
org/apache/commons/proxy/ObjectProvider
org/apache/commons/proxy/ProxyFactory
org/apache/commons/proxy/ProxyUtils
org/apache/commons/proxy/exception/InvokerException
org/apache/commons/proxy/exception/ObjectProviderException
org/apache/commons/proxy/exception/ProxyFactoryException
org/apache/commons/proxy/factory/cglib/CglibProxyFactory
org/apache/commons/proxy/factory/javassist/JavassistInvocation
org/apache/commons/proxy/factory/javassist/JavassistProxyFactory
org/apache/commons/proxy/factory/javassist/JavassistUtils
org/apache/commons/proxy/factory/util/AbstractProxyClassGenerator
org/apache/commons/proxy/factory/util/AbstractSubclassingProxyFactory
org/apache/commons/proxy/factory/util/MethodSignature
org/apache/commons/proxy/factory/util/ProxyClassCache
org/apache/commons/proxy/factory/util/ProxyClassGenerator
org/apache/commons/proxy/interceptor/ExecutorInterceptor
org/apache/commons/proxy/interceptor/FilteredInterceptor
org/apache/commons/proxy/interceptor/InterceptorChain
org/apache/commons/proxy/interceptor/LoggingInterceptor
org/apache/commons/proxy/interceptor/MethodFilter
org/apache/commons/proxy/interceptor/MethodInterceptorAdapter
org/apache/commons/proxy/interceptor/SerializingInterceptor
org/apache/commons/proxy/interceptor/filter/PatternFilter
org/apache/commons/proxy/interceptor/filter/ReturnTypeFilter
org/apache/commons/proxy/interceptor/filter/SimpleFilter
org/apache/commons/proxy/invoker/DuckTypingInvoker
org/apache/commons/proxy/invoker/InvocationHandlerAdapter
org/apache/commons/proxy/invoker/NullInvoker
org/apache/commons/proxy/invoker/XmlRpcInvoker
org/apache/commons/proxy/provider/BeanProvider
org/apache/commons/proxy/provider/CloningProvider
org/apache/commons/proxy/provider/ConstantProvider
org/apache/commons/proxy/provider/NullProvider
org/apache/commons/proxy/provider/ProviderDecorator
org/apache/commons/proxy/provider/SingletonProvider
org/apache/commons/proxy/provider/remoting/BurlapProvider
org/apache/commons/proxy/provider/remoting/HessianProvider
org/apache/commons/proxy/provider/remoting/JaxRpcProvider
org/apache/commons/proxy/provider/remoting/RmiProvider
org/apache/commons/proxy/provider/remoting/SessionBeanProvider