public interface BookManager {void addBook();
}

 1 package com.test;
 2
 3 public class Library implements BookManager {
 4
 5     public void addBook() {
 6         // TODO Auto-generated method stub
 7         System.out.println("增加图书。。。。。");
 8     }
 9
10 }

 1 package com.test;
 2
 3 public class Agent implements BookManager {
 4     private BookManager library;
 5
 6     public BookManager getLibrary() {
 7         return library;
 8     }
 9
10     public void setLibrary(BookManager library) {
11         this.library = library;
12     }
13
14     public void addBook() {
15         // TODO Auto-generated method stub
16         System.out.println("添加图书之前");
17         library.addBook();
18         System.out.println("添加图书之后");
19     }
20
21 }

package com.test;public class BookTest {public static void main(String[] args) {BookManager library = new Library();Agent agent =  new Agent();agent.setLibrary(library);agent.addBook();}
}执行结果为
添加图书之前
增加图书。。。。。
添加图书之后

public interface BookFacade {public void addBook();
}

public class BookFacadeImpl implements BookFacade,system {public void addBook() {// TODO Auto-generated method stubSystem.out.println("增加图书方法。。。");  }public void doSys() {// TODO Auto-generated method stubSystem.out.println("dsfsdfsd");}}

public class BookFacadeProxy implements InvocationHandler {private Object target;  /** * 绑定委托对象并返回一个代理类 * @param target * @return */  public Object bind(Object target) {  this.target = target;  //取得代理对象  return Proxy.newProxyInstance(target.getClass().getClassLoader(),  target.getClass().getInterfaces(), this);   //要绑定接口(这是一个缺陷，cglib弥补了这一缺陷)  }  public Object invoke(Object proxy, Method method, Object[] args)  throws Throwable {  Object result=null;  System.out.println("事物开始");  //执行方法  System.out.println("ClassLoad"+proxy.getClass().getSimpleName());result=method.invoke(target, args);  System.out.println("事物结束");  return result;  }
}

public class TestProxy {public static void main(String[] args) {BookFacadeProxy proxy = new BookFacadeProxy();  BookFacade bookProxy = (BookFacade) proxy.bind(new BookFacadeImpl());  bookProxy.addBook(); ProxyGeneratorUtils.writeProxyClassToHardDisk("F:/$Proxy11.class");}
}

事物开始
增加图书方法。。。
事物结束

Returns an instance of a proxy class for the specified interfacesthat dispatches method invocations to the specified invocationhandler.看看注释就明白了，返回一个代理类的对象，而且还是实现了你进来接口的类public static Object newProxyInstance(ClassLoader loader,Class<?>[] interfaces,InvocationHandler h)throws IllegalArgumentException{if (h == null) {throw new NullPointerException();}/** 生成一个代理类*/Class<?> cl = getProxyClass(loader, interfaces);/** 通过反射用构造方法生成一个对象*/try {Constructor cons = cl.getConstructor(constructorParams);return cons.newInstance(new Object[] { h });} catch (NoSuchMethodException e) {throw new InternalError(e.toString());} catch (IllegalAccessException e) {throw new InternalError(e.toString());} catch (InstantiationException e) {throw new InternalError(e.toString());} catch (InvocationTargetException e) {throw new InternalError(e.toString());}}

public static Class<?> getProxyClass(ClassLoader loader,Class<?>... interfaces)throws IllegalArgumentException{验证接口的长度if (interfaces.length > 65535) {throw new IllegalArgumentException("interface limit exceeded");}这个class 对象就是我们被返回对象的定义Class<?> proxyClass = null;/* collect interface names to use as key for proxy class cache */String[] interfaceNames = new String[interfaces.length];// for detecting duplicatesSet<Class<?>> interfaceSet = new HashSet<>();for (int i = 0; i < interfaces.length; i++) {String interfaceName = interfaces[i].getName();Class<?> interfaceClass = null;try {interfaceClass = Class.forName(interfaceName, false, loader);} catch (ClassNotFoundException e) {}if (interfaceClass != interfaces[i]) {throw new IllegalArgumentException(interfaces[i] + " is not visible from class loader");}/** Verify that the Class object actually represents an* interface.*/if (!interfaceClass.isInterface()) {throw new IllegalArgumentException(interfaceClass.getName() + " is not an interface");}/** Verify that this interface is not a duplicate.*/if (interfaceSet.contains(interfaceClass)) {throw new IllegalArgumentException("repeated interface: " + interfaceClass.getName());}interfaceSet.add(interfaceClass);interfaceNames[i] = interfaceName;}....... 中间省略N多                       生成一个代理class文件，这个就是我们要被返回的class 对象/** Generate the specified proxy class.*/byte[] proxyClassFile = ProxyGenerator.generateProxyClass(proxyName, interfaces);try {proxyClass = defineClass0(loader, proxyName,proxyClassFile, 0, proxyClassFile.length);} catch (ClassFormatError e) {/*

byte[] proxyClassFile = ProxyGenerator.generateProxyClass(proxyName, interfaces);

public final class $Proxy110 extends Proxyimplements BookFacade
{private static Method m1;private static Method m3;private static Method m0;private static Method m2;public $Proxy110(InvocationHandler paramInvocationHandler)throws {super(paramInvocationHandler);}public final boolean equals(Object paramObject)throws {try{return ((Boolean)this.h.invoke(this, m1, new Object[] { paramObject })).booleanValue();}catch (Error|RuntimeException localError){throw localError;}catch (Throwable localThrowable){throw new UndeclaredThrowableException(localThrowable);}}public final void addBook()throws {try{this.h.invoke(this, m3, null);return;}catch (Error|RuntimeException localError){throw localError;}catch (Throwable localThrowable){throw new UndeclaredThrowableException(localThrowable);}}