设计模式 - 代理模式（jdk）

package com.proxy.example;

public interface Employ {
    
    void work();

}

package com.proxy.example;

public class Engineer implements Employ {

    @Override
    public void work() {
        System.out.println("写代码。。。");

    }

}

package com.proxy.example;

public class StaticProxy implements Employ {
    
    private Employ employ;
    
    public StaticProxy(Employ employ) {
        super();
        this.employ = employ;
    }

    @Override
    public void work() {
        punchCard();
        employ.work();
        getfforkunch();
    }
    
    private void punchCard(){
        System.out.println("上班打卡。。。");
    }
    
    private void getfforkunch(){
        System.out.println("下班打卡。。。");
    }

}

package com.proxy.example;

public class TestStaticProxy {

    public static void main(String[] args) {
        StaticProxy proxy = new StaticProxy(new Engineer());
        proxy.work();

    }

}

package com.proxy.example.dynamic;

public interface Manager {
    
    void analysis();

}

package com.proxy.example.dynamic;

public class DemandManager implements Manager {

    @Override
    public void analysis() {
        System.out.println("分析需求。。。");
    }

}

package com.proxy.example.dynamic;

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

public class DynamicProxy implements InvocationHandler {
    
    private Object target;
    
    public DynamicProxy(Object target) {
        this.target = target;
    }
    
    /**
     * proxy:　　指代我们所代理的那个对象
     * method:　 指代的是我们所要调用真实对象的某个方法的Method对象
     * args:　　   指代的是调用真实对象某个方法时接受的参数
     */
    @Override
    public Object invoke(Object proxy, Method method, Object[] args) throws Throwable {
        punchCard();
        Object result = method.invoke(target, args);
        getfforkunch();
        return result;
    }
    
    private void punchCard(){
        System.out.println("上班打卡。。。");
    }
    
    private void getfforkunch(){
        System.out.println("下班打卡。。。");
    }
    
    /**
     * 通过Proxy类的newProxyInstance方法来创建我们的代理类对象，三个参数含义：
     * 第一个参数target.getClass().getClassLoader() ，我们这里使用被代理对象target这个类的ClassLoader对象来加载我们的代理对象
     * 第二个参数target.getClass().getInterfaces()，我们这里为代理对象提供的接口是被代理对象所实现的接口，这样我们生成的代理对象的方法就有我们被代理的对象的方法了
     * 第三个参数this， 指当前的代理对象
     */
    public Object getProxy() {
        return Proxy.newProxyInstance(target.getClass().getClassLoader(), target.getClass().getInterfaces(), this);
    }

}

package com.proxy.example.dynamic;

import com.proxy.example.Employ;
import com.proxy.example.Engineer;

public class TestDynamicProxy {

    public static void main(String[] args) {
        Engineer engineer = new Engineer();
        DynamicProxy engineerProxy = new DynamicProxy(engineer);
        Employ employEngineer = (Employ)engineerProxy.getProxy();
        employEngineer.work();
        
        Manager manager = new DemandManager();
        DynamicProxy managerProxy = new DynamicProxy(manager);
        Manager demandManager = (Manager)managerProxy.getProxy();
        demandManager.analysis();

    }

}