Public interface someclass {
Public abstract void someMethod ();
Public Abstract Void Someharmthod (Final String Text);
Public Class SomeClassImpl Implements SomeClass {
PRIVATE STRING UserName;
Public String UserName {this.username = username;}
Public void someMethod () {system.out.println (this.username);
Public void Someharmthod (Final String Text) {system.out.println (text);}}
Import java.lang.reflect.invocationhandler; import java.lang.reflect.InvocationTargeTexception; import java.lang.reflect.Method;
Public class methodcountinghandler imports invocationhandler {
/ * Whatver Object, You CAN pass one in * / private finAl Object IMPL;
Private int invocationcount = 0;
/ * Constructor * / public methodcounting, {this.impl = IMPL;}
/ * export the invocation count * / public int getInvocationcount () {return infocationcount;}
/ * Implements the interface function of InvocationHandler * / public Object invoke (Object proxy, Method meth, Object [] args) throws Throwable {try {this.invocationCount ; Object result = meth.invoke (impl, args); return result;} Catch (Final InvocationTargeTexception EX) {throw ex.gettargetexception ();}}}
Import java.lang.reflect.invocationhandler; import java.lang.reflect.Proxy;
Public class someclassfactory {
Public static final someclass getDynamicsomeclassproxy () {
/ * GET A Implement Instance of SomeClass * / SomeClassImpl Impl = New SomeClassImpl (System.getProperty ("User.Name"));
IF (! (iMPL InstanceOf SomeClass) Return NULL;
/ * Construct a invocation handler with the impl instance * / InvocationHandler handler = new MethodCountingHandler (impl); / * get the class info, and the class loader used by this factory * / Class [] interfaces = new Class [] {SomeClass. Class}; ClassLoader Loader = SomeClassFactory.class.getClassLoader ();
/ * * Install the handler for all implementations of this interface in this class loader * and return the proxy instance which accords to SomeClass interface * / SomeClass proxy = (SomeClass) Proxy.newProxyInstance (loader, interfaces, handler).;
Return Proxy;
}
Import java.lang.reflect.invocationhandler; import java.lang.reflect.Proxy;
Public class demodynamicproxy {
Public Static Final Void Main (Final String [] args) {
SomeClass Proxy = SomeClassFactory.getDynamicsMeclassProxy ();
Proxy.SOMEMETHOD ();
Proxy.SOMETHERMETHOD ("Our Proxy Works!");
/ * get the handler associated with this proxy instance * / invocationhandler handler = proxy.getinvocationHandler (Proxy);
IF (Handler InstanceOf MethodCountingHandler) {System.out.Println ((MethodCountingHandler) Handler .getinvocationCount ());}}
}
Java's dynamic proxy only supports Interface-based Method Interception. This example is taken from the "Hardcore Java" book.
