Spring-动态代理-模板

ProxyInvocationHandler:

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

//用这个类自动生成代理类
public class ProxyInvocationHandler implements InvocationHandler {

    //被代理的接口
    private Object target;

    public void setTarget(Object target) {
        this.target = target;
    }

    //生成得到代理类
    public Object getProxy(){
        return Proxy.newProxyInstance(this.getClass().getClassLoader(), 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
        log(method.getName());

        //动态代理的本质，就是使用反射机制去实现
        Object result = method.invoke(target,args);

        return result;
    }

    //增加一个日志功能
    public void log(String msg){
        System.out.println("print a " + msg + " method");
    }
}

 

 

Client:

import com.kuang.demo02.UserService;
import com.kuang.demo02.UsrtServiceImpl;


public class Client {
    public static void main(String[] args) {
        //真实角色
        UsrtServiceImpl userService = new UsrtServiceImpl();
        //代理角色，不存在
        ProxyInvocationHandler proxyInvocationHandler = new ProxyInvocationHandler();

        //设置要代理的对象
        proxyInvocationHandler.setTarget(userService);
        //动态生成代理类
        UserService proxy = (UserService) proxyInvocationHandler.getProxy();

        proxy.add();

    }
}

 

 

demo02.UserService:

public interface UserService {
    public void add();
    public void delete();
    public void update();
    public void query();
}

 

demo02.UsrtServiceImpl:

public class UsrtServiceImpl implements UserService {
    public void add(){
        System.out.println("add a user");
    }

    public void delete(){
        System.out.println("delete a user");
    }

    public void update(){
        System.out.println("update a user");
    }

    public void query(){
        System.out.println("find a user");
    }
}