java静态代理与动态代理

╰半橙微兮° 2022-11-09 12:33 143阅读 0赞

# 静态代理 #

#### 接口 ####

package service;
    
    public interface UserService {
        
    
        void add();
    
        void delete();
    
        void list();
    
        void login();
    
        void update();
    }
    #### 实现类
    ```java
    package Impl;
    
    
    import service.UserService;
    
    public class UserServiceImpl implements UserService {
        
        public void add() {
        
            System.out.println("add user");
        }
    
        public void delete() {
        
            System.out.println("delete user");
    
        }
    
        public void list() {
        
            System.out.println("list user");
    
        }
    
        @Override
        public void login() {
        
            System.out.println("login user");
    
        }
    
        @Override
        public void update() {
        
            System.out.println("update user");
        }
    }

#### 测试 ####

@Test
        public void service() {
        
            UserServiceImpl userService = new UserServiceImpl();
            userService.add();
            userService.delete();
            userService.list();
        }
    
        @Test
        public void staticMethod() {
        
            UserServiceImpl userService = new UserServiceImpl();
            UserServiceStaticProxy userServiceStaticProxy = new UserServiceStaticProxy();
            userServiceStaticProxy.setUserService(userService);
            userServiceStaticProxy.add();
            userServiceStaticProxy.delete();
            userServiceStaticProxy.list();
        }

# 动态代理 #

package handler;
    
    import service.UserService;
    
    import java.lang.reflect.InvocationHandler;
    import java.lang.reflect.Method;
    import java.time.Instant;
    
    public class MyInvocationHandler implements InvocationHandler {
        
    
        public MyInvocationHandler(UserService target) {
        
            this.target = target;
        }
    
        private UserService target;
    
        public Object invoke(Object proxy, Method method, Object[] args) throws Throwable {
        
            System.out.println("当前执行的方法是：" + method.getName());
            System.out.println("执行前的时间是：" + Instant.now().toString());
            Thread.sleep(1000);
            Object invoke = method.invoke(target, args);
            System.out.println("执行结束时间是：" + Instant.now().toString());
            return invoke;
        }
    }

#### 测试 ####

@Test
        public void dynamicMethod() throws Exception {
        
            UserService userService = new UserServiceImpl();
            MyInvocationHandler myInvocationHandler = new MyInvocationHandler(userService);
            UserService proxyInstance = (UserService) Proxy.newProxyInstance(userService.getClass().getClassLoader(), userService.getClass().getInterfaces(), myInvocationHandler);
            byte[] classFile = ProxyGenerator.generateProxyClass("$Proxy0", userService.getClass().getInterfaces());
            FileOutputStream out = new FileOutputStream("$Proxy0.class");
            out.write(classFile);
            out.close();
            proxyInstance.add();
            proxyInstance.delete();
            proxyInstance.list();
        }

# 通过字节码反编译动态代理类 #

package handler;
    
    import java.io.DataOutputStream;
    import java.io.FileInputStream;
    import java.io.FileOutputStream;
    import java.util.Scanner;
    
    public class TestGenerate {
        
        public static void main(String[] args) throws Exception {
        
            
            //用注释的代码debug 得到一个txt文件
    //        UserService userService = new UserServiceImpl();
    //        DynamicUserServiceProxy dynamicUserServiceProxy = new DynamicUserServiceProxy(userService);
    //        UserService o = (UserService) Proxy.newProxyInstance(UserController.class.getClassLoader(), new Class[]{UserService.class}, dynamicUserServiceProxy);
    //        o.select();
    //        o.delete();
    //        o.login();
    //        o.add();
    //        o.update();
            
            // 用下面的代码生成proxy.class
            DataOutputStream dataOutputStream = new DataOutputStream(new FileOutputStream("/Users/java0904/IdeaProjects/javaDynamicProxy/src/main/resources/proxy.class"));
            Scanner scanner = new Scanner(new FileInputStream("/Users/java0904/IdeaProjects/javaDynamicProxy/src/main/resources/orgin.txt"));
            while (scanner.hasNext()) {
        
                scanner.next();
                scanner.next();
                dataOutputStream.write(scanner.nextByte());
            }
            scanner.close();
            dataOutputStream.close();
        }
    }

#### 生成的动态代理文件 ####

//
    // Source code recreated from a .class file by IntelliJ IDEA
    // (powered by FernFlower decompiler)
    //
    
    package com.sun.proxy;
    
    import cn.juhe.service.UserService;
    import java.lang.reflect.InvocationHandler;
    import java.lang.reflect.Method;
    import java.lang.reflect.Proxy;
    import java.lang.reflect.UndeclaredThrowableException;
    
    public final class $Proxy0 extends Proxy implements UserService {
        
        private static Method m1;
        private static Method m2;
        private static Method m3;
        private static Method m5;
        private static Method m7;
        private static Method m6;
        private static Method m0;
        private static Method m4;
    
        public $Proxy0(InvocationHandler var1) throws  {
        
            super(var1);
        }
    
        public final boolean equals(Object var1) throws  {
        
            try {
        
                return (Boolean)super.h.invoke(this, m1, new Object[]{
        var1});
            } catch (RuntimeException | Error var3) {
        
                throw var3;
            } catch (Throwable var4) {
        
                throw new UndeclaredThrowableException(var4);
            }
        }
    
        public final String toString() throws  {
        
            try {
        
                return (String)super.h.invoke(this, m2, (Object[])null);
            } catch (RuntimeException | Error var2) {
        
                throw var2;
            } catch (Throwable var3) {
        
                throw new UndeclaredThrowableException(var3);
            }
        }
    
        public final void add() throws  {
        
            try {
        
                super.h.invoke(this, m3, (Object[])null);
            } catch (RuntimeException | Error var2) {
        
                throw var2;
            } catch (Throwable var3) {
        
                throw new UndeclaredThrowableException(var3);
            }
        }
    
        public final void delete() throws  {
        
            try {
        
                super.h.invoke(this, m5, (Object[])null);
            } catch (RuntimeException | Error var2) {
        
                throw var2;
            } catch (Throwable var3) {
        
                throw new UndeclaredThrowableException(var3);
            }
        }
    
        public final void select() throws  {
        
            try {
        
                super.h.invoke(this, m7, (Object[])null);
            } catch (RuntimeException | Error var2) {
        
                throw var2;
            } catch (Throwable var3) {
        
                throw new UndeclaredThrowableException(var3);
            }
        }
    
        public final void login() throws  {
        
            try {
        
                super.h.invoke(this, m6, (Object[])null);
            } catch (RuntimeException | Error var2) {
        
                throw var2;
            } catch (Throwable var3) {
        
                throw new UndeclaredThrowableException(var3);
            }
        }
    
        public final int hashCode() throws  {
        
            try {
        
                return (Integer)super.h.invoke(this, m0, (Object[])null);
            } catch (RuntimeException | Error var2) {
        
                throw var2;
            } catch (Throwable var3) {
        
                throw new UndeclaredThrowableException(var3);
            }
        }
    
        public final void update() throws  {
        
            try {
        
                super.h.invoke(this, m4, (Object[])null);
            } catch (RuntimeException | Error var2) {
        
                throw var2;
            } catch (Throwable var3) {
        
                throw new UndeclaredThrowableException(var3);
            }
        }
    
        static {
        
            try {
        
                m1 = Class.forName("java.lang.Object").getMethod("equals", Class.forName("java.lang.Object"));
                m2 = Class.forName("java.lang.Object").getMethod("toString");
                m3 = Class.forName("cn.juhe.service.UserService").getMethod("add");
                m5 = Class.forName("cn.juhe.service.UserService").getMethod("delete");
                m7 = Class.forName("cn.juhe.service.UserService").getMethod("select");
                m6 = Class.forName("cn.juhe.service.UserService").getMethod("login");
                m0 = Class.forName("java.lang.Object").getMethod("hashCode");
                m4 = Class.forName("cn.juhe.service.UserService").getMethod("update");
            } catch (NoSuchMethodException var2) {
        
                throw new NoSuchMethodError(var2.getMessage());
            } catch (ClassNotFoundException var3) {
        
                throw new NoClassDefFoundError(var3.getMessage());
            }
        }
    }