JDK动态代理。

使用JDK动态代理  被代理的类 ，必须要实现接口。 

PersonDao.java

package com.zf.proxy;public interface PersonDao {public void add();public void update();}

PersonDaoImpl.java

package com.zf.proxy;public class PersonDaoImpl implements PersonDao {@Overridepublic void add() {System.out.println("personDao add()...");}@Overridepublic void update() {System.out.println("personDao update()...");  }}

ProxyFactory.java

package com.zf.proxy;import java.lang.reflect.InvocationHandler;import java.lang.reflect.Method;import java.lang.reflect.Proxy;public class ProxyFactory<E> implements InvocationHandler{private E target ;public ProxyFactory(E target){this.target = target ;}@Overridepublic Object invoke(Object proxy, Method method, Object[] args)throws Throwable {System.out.println("before...");Object obj = method.invoke(target, args);System.out.println("after...");return obj ;}public E getProxyInstance(){return (E)Proxy.newProxyInstance(target.getClass().getClassLoader(),target.getClass().getInterfaces(), this);}}

Test.java

package com.zf.proxy;public class Test {public static void main(String[] args) {PersonDao personDao = new PersonDaoImpl();//泛型 传递接口类型进去ProxyFactory<PersonDao> pf = new ProxyFactory<PersonDao>(personDao);personDao = pf.getProxyInstance();personDao.update();}}

代理链条的实现。

package com.zf.proxy;public interface BaseProxy<E> {E getProxyInstance();void setTarget(E target);}

package com.zf.proxy;import java.lang.reflect.InvocationHandler;import java.lang.reflect.Method;import java.lang.reflect.Proxy;public class TimeProxyFactory<E> implements InvocationHandler , BaseProxy<E>{private E target ;@Overridepublic Object invoke(Object proxy, Method method, Object[] args)throws Throwable {System.out.println("log:" + target.getClass().getName() + "." + method.getName() +  " start...");Object obj = method.invoke(target, args);System.out.println("log:" + target.getClass().getName() + "." + method.getName() +  " end...");return obj ;}  public E getProxyInstance(){return (E)Proxy.newProxyInstance(target.getClass().getClassLoader(),target.getClass().getInterfaces(), this);}@Overridepublic void setTarget(E target) {this.target = target ;}}

package com.zf.proxy;import java.lang.reflect.InvocationHandler;import java.lang.reflect.Method;import java.lang.reflect.Proxy;public class LogProxyFactory<E> implements InvocationHandler, BaseProxy<E>{private E target ;@Overridepublic Object invoke(Object proxy, Method method, Object[] args)throws Throwable {long start = System.currentTimeMillis();Object obj = method.invoke(target, args);long end = System.currentTimeMillis();System.out.printf("方法%s用时：%d\n" , target.getClass().getName() + "." + method.getName() , (end - start));return obj ;}//这里会将代理对象转换为E的类型，所以E应该为接口类型。而不能是接口的实现类。public E getProxyInstance(){return (E)Proxy.newProxyInstance(target.getClass().getClassLoader(),target.getClass().getInterfaces(), this);}@Overridepublic void setTarget(E target) {this.target = target ;}}

package com.zf.proxy;public class ProxyChain<E> {  private E target ; public ProxyChain(E target){this.target = target ;}public void addProxy(BaseProxy<E> bp){bp.setTarget(target);target = bp.getProxyInstance();}public E getProxyInstance() {return target;  }}

package com.zf.proxy;public class Test {public static void main(String[] args) {PersonDao personDao = new PersonDaoImpl();//泛型 传递接口类型进去ProxyChain<PersonDao> pc = new ProxyChain<PersonDao>(personDao);pc.addProxy(new TimeProxyFactory<PersonDao>());pc.addProxy(new LogProxyFactory<PersonDao>());personDao = pc.getProxyInstance();personDao.update();}}