**1.UserService** ~~~ package com.nobb.service; /** * 動態代理實驗 */ public interface UserService { void save(); void delete(); void update(); void find(); } ~~~ **2.UserServiceImpl** ~~~ package com.nobb.service; import org.springframework.stereotype.Service; @Service public class UserServiceImpl implements UserService{ public String test(){ return "success"; } @Override public void save() { // int i = 1/0; System.out.println("save"); } @Override public void delete() { System.out.println("delete"); } @Override public void update() { System.out.println("update"); } @Override public void find() { System.out.println("find"); } } ~~~ **3.UserServiceDynamicProxyFactory** ~~~ package com.nobb.proxy; import com.nobb.service.UserService; import java.lang.reflect.InvocationHandler; import java.lang.reflect.Method; import java.lang.reflect.Proxy; public class UserServiceDynamicProxyFactory implements InvocationHandler{ //被代理對象 private UserService target; //UserServiceImpl //在構造器注入了目標對象 public UserServiceDynamicProxyFactory(UserService target){ this.target = target; } //創建代理類對象 -> 生成接口實現類 //參數1: 類加載器,加載生成的類 //參數2: 指定待實現的接口,因為一個類可以實現多個接口,傳入接口class數組 //參數3: 指定接口實現類實現方法的行為 public UserService getUserService(){ return (UserService) Proxy.newProxyInstance(this.getClass().getClassLoader(), new Class[]{UserService.class}, this); } //指定代理類的行為 //參數1:代理對象 //參數2: 指定調用的是接口中的哪一個方法 //參數3: 方法執行的參數 @Override public Object invoke(Object proxy, Method method, Object[] args) throws Throwable { //開啟事務 System.out.println(method); System.out.println("開啟事務"); //執行業務代碼 Object o = method.invoke(target, args); //關閉事務 System.out.println("關閉事務"); return o; } } ~~~ **4.Demo1** ~~~ package com.nobb.proxy; import com.nobb.service.UserService; import com.nobb.service.UserServiceImpl; /** * 動態代理測試類 */ public class Demo1 { public static void main(String[] args) { UserService target = new UserServiceImpl(); //拿到接口的實現類 UserServiceDynamicProxyFactory factory = new UserServiceDynamicProxyFactory(target); UserService userService = factory.getUserService(); //實際執行的是代理類 userService.save(); // userService.delete(); // userService.update(); // userService.find(); System.out.println(userService instanceof UserService); } } ~~~