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JDK动态代理实现

程序员文章站 2022-07-15 10:27:09
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JDKProxy.java

package com.company;

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

public class JDKProxy {

    public static void main(String[] args){

        UserDaoImpl userDao = new UserDaoImpl();

        Class[] interfaces={UserDao.class};
       UserDao dao=(UserDao)Proxy.newProxyInstance(JDKProxy.class.getClassLoader(),interfaces,new UserDaoProxy(userDao));
       int result=dao.add(1,2);
       System.out.println(result);
    }
}

class UserDaoProxy implements InvocationHandler{

    private Object obj;
    public UserDaoProxy(Object obj){
        this.obj = obj;
    }

    @Override
    public Object invoke(Object proxy, Method method, Object[] args) throws Throwable {

        //方法之前
        System.out.println("方法之前执行..."+method.getName()+" :传递的参数..."+ Arrays.toString(args));

        //被增强的方法执行
        Object res = method.invoke(obj,args);

        //方法之后
        System.out.println("方法之后执行..."+obj);

        return res;
    }
}

UserDao.java

 

package com.company;

public interface UserDao {
    public int add(int a,int b);

    //public String update(String id);
}
UserDaoImpl.java

package com.company;

public class UserDaoImpl implements UserDao{

    @Override
    public int add(int a, int b) {
        System.out.println("add方法执行了");
        return a+b;
    }

    /*@Override
    public String update(String id) {
        System.out.println("update方法执行了");
        return id;
    }*/
}
相关标签: spring 5