【Spring第八篇】代理模式（静态、动态）：Proxy_Mode

川长思鸟来 2023-09-29 10:08 1阅读 0赞

`在了解aop之前我们先来了解代理模式`

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#### 静态代理模式示例一 ####

租房接口类 Rent

public interface Rent {
        
        public void rent();
    }

房东类 Host

public class Host implements Rent{
        
        @Override
        public void rent() {
        
            System.out.println("房东出租房子");
        }
    }

`中介类 代理 Proxy 可以附带自己的一些属性`

@Data
    @AllArgsConstructor
    @NoArgsConstructor
    public class Proxy implements Rent{
        
    
        private Host host;
    
        @Override
        public void rent() {
        
            host.rent();
            seeHouse();
            fare();
        }
    
        public void seeHouse(){
        
            System.out.println("中介带你看房");
        }
    
        public void fare(){
        
            System.out.println("收中介费");
        }
    }

租客类 Client

public class Client {
        
        public static void main(String[] args) {
        
            
            Host host = new Host();
            Proxy proxy = new Proxy(host);
    
            //代理，中介帮房东租房子， 代理角色一般会有一些附属操作
            proxy.rent();
        }
    
    }

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#### 静态代理模式示例二 ####

service接口类 UserService

public interface UserService {
        
    
        public void add();
        public void delete();
        public void update();
        public void query();
    
    }

service接口实现类

public class UserServiceImpl implements UserService{
        
        @Override
        public void add() {
        
            System.out.println("增加了一个用户");
        }
    
        @Override
        public void delete() {
        
            System.out.println("删除了一个用户");
        }
    
        @Override
        public void update() {
        
            System.out.println("修改了一个用户");
        }
    
        @Override
        public void query() {
        
            System.out.println("查询了一个用户");
        }
    }

代理 service实现类 UserServiceProxy

public class UserServiceProxy implements UserService{
        
    
    
        private UserServiceImpl userService;
        public void setUserService(UserServiceImpl userService) {
        
            this.userService = userService;
        }
    
        @Override
        public void add() {
        
            log("add");
            userService.add();
        }
    
        @Override
        public void delete() {
        
            log("delete");
            userService.delete();
        }
    
        @Override
        public void update() {
        
            log("update");
            userService.update();
        }
    
        @Override
        public void query() {
        
            log("query");
            userService.query();
        }
    
        //打印日志方法
        public void log(String msg){
        
            System.out.println("使用了"+msg+"方法");
        }
    
    }

用户执行

public class Client {
        
    
        public static void main(String[] args) {
        
    
            UserServiceImpl userService = new UserServiceImpl();
    
            UserServiceProxy proxy = new UserServiceProxy();
            proxy.setUserService(userService);
    
            proxy.add();
            System.out.println("==========");
            proxy.delete();
            System.out.println("==========");
            proxy.update();
            System.out.println("==========");
            proxy.query();
        }
    
    }

`总结：当我们的用户想要去调用service实现类的方法的时候，这时并不直接从service实现类中取得某个方法，而是通过接口去取`

`注意点：需要在代理实现类 UserServiceProxy 中编写以下代码`

private UserServiceImpl userService;
    
    public void setUserService(UserServiceImpl userService) {
        
        this.userService = userService;
    }

当我们的用户 Client 在调用的使用只需编写以下代码

UserServiceImpl userService = new UserServiceImpl();
    
    UserServiceProxy proxy = new UserServiceProxy();
    
    proxy.setUserService(userService);
    
    		proxy.add();
            System.out.println("==========");
            proxy.delete();
            System.out.println("==========");
            proxy.update();
            System.out.println("==========");
            proxy.query();

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#### 动态代理模式实例三 ####

租房 接口 Rent

public interface Rent {
        
    
    
        public void rent();
    
    }

房东 Host 实现接口

public class Host implements Rent {
        
    
        @Override
        public void rent() {
        
            System.out.println("房东出租房子");
        }
    }

代理类 Proxy\_InvocationHandler 实现 InvocationHandler接口

`InvocationHandler`

public Object invoke(Object proxy, Method method, Object[] args)
        throws Throwable;

package com.kk.Demo03;
    
    import java.lang.reflect.InvocationHandler;
    import java.lang.reflect.Method;
    import java.lang.reflect.Proxy;
    
    public class Proxy_InvocationHandler implements InvocationHandler {
        
    
    
        //被代理的接口
        private Rent rent;
    
        public void setRent(Rent rent) {
        
            this.rent = rent;
        }
    
    
        /**
         *  public static Object newProxyInstance(ClassLoader loader,
         *                                           Class<?>[] interfaces,
         *                                           InvocationHandler h)
         * 
         */
        //生成得到代理类
        public Object getProxy(){
        
         return  Proxy.newProxyInstance(this.getClass().getClassLoader(), rent.getClass().getInterfaces(),this );
        }
    
    
        //处理代理实例并返回结果
        @Override
        public Object invoke(Object proxy, Method method, Object[] args) throws Throwable {
        
    
            seeHouse();
            fare();
    
            /**
             * public Object invoke(Object obj, Object... args)
             */
            //动态代理的本质就是实现反射机制
            Object result = method.invoke(rent, args);
            return result;
        }
    
    
        public void seeHouse(){
        
            System.out.println("中介带你看房");
        }
    
        public void fare(){
        
            System.out.println("收中介费");
        }
    }

用户

public class Client {
        
        public static void main(String[] args) {
        
            //真实角色
            Host host = new Host();
    
            //代理角色
            Proxy_InvocationHandler handler = new Proxy_InvocationHandler();
    
            //通过调用 程序 处理  角色 来处理 要调用 的接口对象
            handler.setRent(host);
    
            Rent proxy = (Rent) handler.getProxy();//这里的proxy就是动态生成的，我们并没有写
    
            proxy.rent();
        }
    
    }

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#### 动态代理模式实例四 ####

Proxy\_InvocationHandler

package com.kk.Demo04;
    
    import com.kk.Demo03.Rent;
    
    import java.lang.reflect.InvocationHandler;
    import java.lang.reflect.Method;
    import java.lang.reflect.Proxy;
    
    @SuppressWarnings("all")
    public class Proxy_InvocationHandler implements InvocationHandler {
        
    
    
        //被代理的接口
        private Object target;
    
    
        public void setTarget(Object target) {
        
            this.target = target;
        }
    
        //生成得到代理类
        public Object getProxy(){
        
         return  Proxy.newProxyInstance(this.getClass().getClassLoader(), target.getClass().getInterfaces(),this );
        }
    
    
        //处理代理实例并返回结果
        @Override
        public Object invoke(Object proxy, Method method, Object[] args) throws Throwable {
        
    
            log(method.getName());
    
            //动态代理的本质就是实现反射机制
            Object result = method.invoke(target, args);
            return result;
        }
    
    
    
        public void log(String msg){
        
            System.out.println("执行了"+msg+"方法");
        }
    
    
    }

Client

package com.kk.Demo04;
    
    import com.kk.Demo02.UserService;
    import com.kk.Demo02.UserServiceImpl;
    
    public class Client {
        
        public static void main(String[] args) {
        
    
            //真实角色
            UserServiceImpl userService = new UserServiceImpl();
    
            //代理角色，不存在
            Proxy_InvocationHandler handler = new Proxy_InvocationHandler();
    
            //设置要代理的对象
            handler.setTarget(userService);
    
            //动态生成代理类
            UserService proxy = (UserService) handler.getProxy();
    
            proxy.add();
    
    
        }
    }

![\[外链图片转存失败,源站可能有防盗链机制,建议将图片保存下来直接上传(img-xSLrLC4s-1649854268149)(C:\\Users\\30666\\AppData\\Roaming\\Typora\\typora-user-images\\image-20220310170201823.png)\]][img-xSLrLC4s-1649854268149_C_Users_30666_AppData_Roaming_Typora_typora-user-images_image-20220310170201823.png]

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[img-xSLrLC4s-1649854268149_C_Users_30666_AppData_Roaming_Typora_typora-user-images_image-20220310170201823.png]: https://img-blog.csdnimg.cn/f1d373b1120a43469c1433f832906987.png?x-oss-process=image/watermark,type_d3F5LXplbmhlaQ,shadow_50,text_Q1NETiBA5LiD5a-75YyX6YeM,size_17,color_FFFFFF,t_70,g_se,x_16