Java动态代理

什么是动态代理

为什么要用动态代理

实战demo

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

public class ProxyTest {

    public static void main(String[] args) {
        UserServiceProxy userServiceProxy = new UserServiceProxy(new UserServiceImpl());
        UserService aaa = userServiceProxy.getInstance();
        System.out.println(aaa.getUserName());
        System.out.println(aaa.getUserAge());
    }

}


interface UserService {

    String getUserName();

    int getUserAge();
}

class UserServiceImpl implements UserService {

    @Override
    public String getUserName() {
        System.out.println("获取userName");
        return "张三";
    }

    @Override
    public int getUserAge() {
        return 10;
    }
}

class UserServiceProxy implements InvocationHandler {

    public UserService userService;

    public UserServiceProxy(UserService userService) {
        this.userService = userService;
    }

    public UserService getInstance() {
        return (UserService) Proxy.newProxyInstance(
                //指定代理对象的类加载器
                userService.getClass().getClassLoader(),
                //代理对象需要实现的接口，可以同时指定多个接口
                userService.getClass().getInterfaces(),
                //方法调用的实际处理者，代理对象的方法调用都会转发到这里
                this
        );
    }

    @Override
    public Object invoke(Object proxy, Method method, Object[] args) throws Throwable {
        System.out.println("dynamic proxy start...");
        Object result = method.invoke(userService,args);
        if (method.getName().equals("getUserName")) {
            System.out.println("针对getUserName进行增强处理");
            result = "李四";
        } else {
            System.out.println("其他方法不增强");
        }
        System.out.println("dynamic proxy end...");
        return result;
    }
}

控制台输出：

来源：CSDN

作者：雪落南城

链接：https://blog.csdn.net/lbh199466/article/details/104613850