java--代理模式原理2(動態代理+監聽者)

package cn.hncu.proxy.util;

public interface IDog {

    public void run();
}

package cn.hncu.proxy.util;

public class Dog implements IDog{

    private String name;
    public Dog(){
        this.name="小不點";
    }
    @Override
    public void run() {
        System.out.println(name+" 正在跑...");
    }
}

package cn.hncu.proxy.util;

public interface IPerson {

    public void sayHello();
}

package cn.hncu.proxy.util;

public class Person implements IPerson {

    private String name;
    public Person(String name){
        this.name=name;
    }
    @Override
    public void sayHello() {
        System.out.println("my name is "+name);

    }

}

動態代理

package cn.hncu.proxy.util;

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

public class ProxyUtils implements InvocationHandler{

    private Object obj=null;
    private ProxyUtils(Object obj){
        this.obj=obj;
    }
    //給一個原型對象就返回一個代理對象
    public static Object getProxy(Object obj){
        Object nObj=Proxy.newProxyInstance(ClassLoader.getSystemClassLoader(), 
                obj.getClass().getInterfaces(), 
                new ProxyUtils(obj));//真正的構造傳參
        return nObj;
    }
    @Override
    public Object invoke(Object proxy, Method method, Object[] args)
            throws Throwable {
        System.out.println("前攔。。。這裏可以添加監聽者模式");
        Object obj=method.invoke(proxy, args);
        System.out.println("後攔。。。這裏可以添加監聽者模式");
        return obj;
    }

}

動態代理+監聽者

package cn.hncu.proxy.util;

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

public class ProxyUtils2 implements InvocationHandler{

    private Object obj=null;
    public ProxyUtils2(Object obj){
        this.obj=obj;
    }
    //給一個原型對象就返回一個代理對象
    public Object getProxy(){
        Object nObj=Proxy.newProxyInstance(ClassLoader.getSystemClassLoader(), 
                obj.getClass().getInterfaces(), 
                this);
        return nObj;
    }
    private A a;
    public void addXXXListener(A a){
        this.a=a;
    }
    @Override
    public Object invoke(Object proxy, Method method, Object[] args)
            throws Throwable {
        if(a!=null){
            a.before();
        }
        System.out.println("前攔。。。這裏可以添加監聽者模式");
        Object nObj=method.invoke(obj, args);
        System.out.println("後攔。。。這裏可以添加監聽者模式");
        if(a!=null){
            a.after();
        }
        return nObj;
    }

}
interface A {
    public void before();
    public void after();
}

演示

package cn.hncu.proxy.util;

import org.junit.Test;

public class Client {

    //實現動態代理
    @Test
    public void test(){
        Person p=new Person("xzm");
        IPerson ip=(IPerson) ProxyUtils.getProxy(p);
        ip.sayHello();

        Dog d=new Dog();
        IDog id=(IDog) ProxyUtils.getProxy(d);
        id.run();
    }
    //引入監聽者模式+實現動態代理
    @Test
    public void test2(){
        ProxyUtils2 p=new ProxyUtils2(new Person("xzm"));
        IPerson ip=(IPerson) p.getProxy();
        p.addXXXListener(new A() {

            @Override
            public void before() {
                System.out.println("你好,幫你設置編碼");
            }

            @Override
            public void after() {
                System.out.println("再見,資源收回來");
            }
        });
        ip.sayHello();
    }
}