java 动态代理的使用

1.接口Human.java 

public interface Human {  
    void say();  
}

2.Human的实现类 Person 

public class Person implements Human {  
  
    @Override  
    public void say() {  
        System.out.println("haha");  
    }  
  
}

3.处理类   

import java.lang.reflect.InvocationHandler;  
import java.lang.reflect.Method;  
  
public class Hander implements InvocationHandler {  
    private Object obj;  
    public Hander(Object obj) {  
        this.obj = obj;  
    }  
    public Hander() {  
    }  
    @Override  
    public Object invoke(Object proxy, Method method, Object[] args)  
            throws Throwable {  
        System.out.println("before");  
        method.invoke(obj, args);  
        System.out.println("after");  
        return null;  
    }  
  
}

4. 使用  

import java.lang.reflect.Proxy;  
  
public class Main {  
  
    public static void main(String[] args) {  
        // TODO Auto-generated method stub  
        Human i = (Human) Proxy.newProxyInstance(Thread.currentThread()  
                .getContextClassLoader(), Person.class.getInterfaces(),  
                new Hander(new Person()));  
        i.say();  
    }  
  
}

5. 输出结果 

before  
haha  
after