设计模式之——代理模式(动态代理）

package proxypackage;
public interface HelloService {
	public void getName(String name);
	public void echoMessage(String msg);
}

接口实现类：

package proxypackage;
public class HelloServiceImpl implements HelloService{
	public void echoMessage(String msg) {
		System.out.println("echo:" + msg);
	}
	public void getName(String name) {
		System.out.println("The name is :" + name);
	}
}

动态代理产生工厂类。

package proxypackage;
import java.lang.reflect.InvocationHandler;
import java.lang.reflect.Method;
import java.lang.reflect.Proxy;
public class HelloServiceProxyFactory {
	public static HelloService getHelloServiceProxy(final HelloService helloService){
		InvocationHandler handler = new InvocationHandler(){
			public Object invoke(Object proxy,
		              Method method,
		              Object[] args)
		              throws Exception{
				 System.out.println("before calling "+method);
				Object result = method.invoke(helloService, args);
				 System.out.println("after calling "+method);
				return result;
			}
		};
		HelloService hello = (HelloService)Proxy.newProxyInstance(HelloService.class.getClassLoader(), new Class[]{HelloService.class}, handler
				);
		return hello;
	}
}

调用类：

package proxypackage;
public class client2 {
	public static void main(String[] args) throws Exception{
		HelloService helloService = new HelloServiceImpl();
		HelloService proxy = HelloServiceProxyFactory.getHelloServiceProxy(helloService);
		proxy.echoMessage("good");
	}
}

输出结果：

before calling public abstract void proxypackage.HelloService.echoMessage(java.lang.String)
echo:good
after calling public abstract void proxypackage.HelloService.echoMessage(java.lang.String)

在动态代理产生工厂里面应用了反射机制。

 

下面为静态代理与动态代理测试类：

/**
 * 
 */
package com.lwf.exception;

import java.lang.reflect.InvocationHandler;
import java.lang.reflect.Method;
import java.lang.reflect.Proxy;

public class TestProxy {
	public static void main(String[] args) {
		HelloServiceProxy helloServiceProxy = new HelloServiceProxy(new HelloServiceImpl());
		helloServiceProxy.echoMessage("3333");
		helloServiceProxy.printMsg();
		
		System.out.println("--------------------------------------------------");
		
		HelloService ser = HelloServiceDyProxy.getHelloServiceProxy(new HelloServiceImpl());
		ser.echoMessage("eeee");
		ser.printMsg();
		
	}
}

interface HelloService{
	public String echoMessage(String msg);
	public void printMsg();
}

class HelloServiceImpl implements HelloService{
	public String echoMessage(String msg){
		System.out.println("echoMessage in impl");
		return "";
	}
	public void printMsg(){
		System.out.println("printMsg in impl");
	}
}

class HelloServiceProxy  implements HelloService{
	HelloService helloService;
	public HelloServiceProxy(HelloService helloService){
		this.helloService = helloService;
	}
	public String echoMessage(String msg){
		System.out.println("befor call impl echoMessage");
		return helloService.echoMessage(msg);
	}
	public void printMsg(){
		System.out.println("befor call impl printMsg");
		helloService.printMsg();
		System.out.println("after call impl printMsg");
	}
}

class HelloServiceDyProxy {
	public static HelloService getHelloServiceProxy(
			final HelloService helloService) {
		InvocationHandler handler = new InvocationHandler() {
			public Object invoke(Object proxy, Method method, Object[] args)
					throws Exception {
				System.out.println("before calling " + method);
				Object result = method.invoke(helloService, args);
				System.out.println("after calling " + method);
				return result;
			}
		};
		HelloService hello = (HelloService) Proxy.newProxyInstance(
				HelloService.class.getClassLoader(),
				new Class[] { HelloService.class }, handler);
		return hello;
	}
}

 运行结果

befor call impl echoMessage
echoMessage in impl
befor call impl printMsg
printMsg in impl
after call impl printMsg
--------------------------------------------------
before calling public abstract java.lang.String com.lwf.exception.HelloService.echoMessage(java.lang.String)
echoMessage in impl
after calling public abstract java.lang.String com.lwf.exception.HelloService.echoMessage(java.lang.String)
before calling public abstract void com.lwf.exception.HelloService.printMsg()
printMsg in impl
after calling public abstract void com.lwf.exception.HelloService.printMsg()