ProxyInvocationHandler的用法

大家好，欢迎来到IT知识分享网。

ProxyInvocationHandler的用法

package Demo02;

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

public class ProxyInvocationHandler implements InvocationHandler {
    //被代理的接口
    private Object target;

    public void setTarget(Object target) {
        this.target = target;
    }
    public Object getProxy(){
        return Proxy.newProxyInstance(this.getClass().getClassLoader(),
                this.target.getClass().getInterfaces(),
                this);

    }
    //处理代理实例，并返回结果

    public Object invoke(Object proxy, Method method, Object[] args) throws Throwable {
        log(method.getName());
        Object res= method.invoke(target,args);
        //fare();
        return res;
    }
    /*public void seeHorse(){
        System.out.println("看房子");
    }
    public void fare(){
        System.out.println("交房租");
    }*/
    public void log(String msg){
        System.out.println("执行了"+msg+"方法");
    }
}

Client的代码

public class Client {
    public static void main(String[] args) {
        //真实角色
        UserServiceImpl userService = new UserServiceImpl();
        //代理角色，不存在的
        ProxyInvocationHandler pih = new ProxyInvocationHandler();
        //设置要代理的对象
        pih.setTarget(userService);
        //动态生成代理类
        UserService proxy = (UserService) pih.getProxy();
        proxy.delete();
    }
}

UserServiceImpl的代码

package Demo01;
//真实对象
public class UserServiceImpl implements UserService{
    @Override
    public void add() {
        System.out.println("增加了一个");
    }

    @Override
    public void delete() {
        System.out.println("删除了一个");
    }

    @Override
    public void update() {
        System.out.println("修改了一个");
    }

    @Override
    public void select() {
        System.out.println("查询了一个");
    }

}

UserServiceProxy的代码

package Demo01;
//代理
public class UserServiceProxy implements UserService{
    private UserServiceImpl userService;

    public void setUserService(UserServiceImpl userService) {
        this.userService = userService;
    }

    @Override
    public void add() {
    log("add");
        userService.add();
    }

    @Override
    public void delete() {
        log("delete");
        userService.delete();

    }

    @Override
    public void update() {
        log("update");
        userService.update();

    }

    @Override
    public void select() {
        log("select");
        userService.select();

    }
    public void log(String msg){
        System.out.println("使用了"+msg+"的方法！");
    }
}