Java Dynamic Agent

First define an interface

 Public Interface Subject {    void  printf ();}

interface implemented by proxy class

 Public class Implements Subject {    @Override    publicvoid  printf () {        System.out.println ( "This is a realsubject ' s printf ()");    }    }

Define Subjectinvocationhandler Implement Invocationhandler interface

 Public classSubjectinvocationhandlerImplementsinvocationhandler{//the object being proxied    PrivateObject Proxy;  PublicSubjectinvocationhandler (Object proxy) { This. Proxy =proxy; }        /*** Proxy Object Calling method * method called methods * Args Call method's parameters * Return call method returned value*/@Override PublicObject Invoke (Object proxy, Method method, object[] args)throwsthrowable {System.out.println ("Subjectinvocationhandler Invoke Prepare"); Object result= Method.invoke ( This. Proxy, args); System.out.println ("Subjectinvocationhandler invoke Post"); returnresult; }}

Final Test

 Public classProxytest { Public Static voidMain (string[] args) {realsubject realsubject=NewRealsubject (); Class<?> CLZ =Realsubject.getclass (); //get class for proxy classesClass<?> PROXYCLZ =Proxy.getproxyclass (Clz.getclassloader (), clz.getinterfaces ()); Try {            //get the constructor with the Invocationhandler parameterconstructor<?> Constructor = Proxyclz.getconstructor (Invocationhandler.class); //instantiating a proxy object with a constructorSubject Proxysubject = (Subject) constructor.newinstance (NewSubjectinvocationhandler (realsubject));        Proxysubject.printf (); } Catch(Exception e) {e.printstacktrace (); }                //using the method in proxy one stepSubject Proxysubject = (Subject) proxy.newproxyinstance (Clz.getclassloader (), clz.getinterfaces (),NewSubjectinvocationhandler (realsubject));            Proxysubject.printf (); }}

Java Dynamic Agent