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 {


	@Override
	public void add() {
		System.out.println("personDao add()...");
	}


	@Override
	public 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 ;
	}


	@Override
	public 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 ;

	@Override
	public 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);
	}

	@Override
	public 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 ;


	@Override
	public 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);
	}

	@Override
	public 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();
		
	}

}