spring AOP代理错误

Posted 2022-08-03 amcomputer

1 报错信息

Exception in thread "main" org.springframework.beans.factory.BeanNotOfRequiredTypeException: Bean named 'userService' is expected to be of type 'com.yang.service.UserServiceImpl' but was actually of type 'com.sun.proxy.$Proxy5'
	at org.springframework.beans.factory.support.AbstractBeanFactory.doGetBean(AbstractBeanFactory.java:392)
	at org.springframework.beans.factory.support.AbstractBeanFactory.getBean(AbstractBeanFactory.java:204)
	at org.springframework.context.support.AbstractApplicationContext.getBean(AbstractApplicationContext.java:1089)
	at com.yang.service.MyTest.main(MyTest.java:19)

其中，IOC容器内容为：

<?xml version="1.0" encoding="UTF-8"?>
<beans xmlns="http://www.springframework.org/schema/beans"
       xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
       xmlns:context="http://www.springframework.org/schema/context"
       xmlns:aop="http://www.springframework.org/schema/aop"
       xsi:schemaLocation="http://www.springframework.org/schema/beans
       https://www.springframework.org/schema/beans/spring-beans.xsd
        http://www.springframework.org/schema/context
       https://www.springframework.org/schema/context/spring-context.xsd
      http://www.springframework.org/schema/aop
       https://www.springframework.org/schema/aop/spring-aop.xsd">

    <context:annotation-config/>
    <!--第一步，先注册bean-->
    <bean id="userService" class="com.yang.service.UserServiceImpl"></bean>
    <bean id="log" class="com.yang.log.Log"></bean>
    <bean id="afterlog" class="com.yang.log.AfterLog"></bean>

    <!--第二步，配置aop：需要在文件头导入支持-->
    <aop:config>
<!--切入点，然后写表达式，表面在哪里类的方法进行切入，需要表面方法，参数等等情况-->
        <aop:pointcut id="pointcut" expression="execution(* com.yang.service.UserServiceImpl.*(..))"/>

<!--    执行环绕增加-->
        <aop:advisor advice-ref="log" pointcut-ref="pointcut"></aop:advisor>
        <aop:advisor advice-ref="afterlog" pointcut-ref="pointcut"></aop:advisor>
    </aop:config>

</beans>

2 分析

spring AOP只能代理接口，不能代理具体的实现类。故需要修改下面的代码：

package com.yang.service;

import org.springframework.context.ApplicationContext;
import org.springframework.context.support.ClassPathXmlApplicationContext;

/**
 * @ClassName MyTest
 * @Author yang
 * @Description //TODO
 * @Date 22/07/23 16:36
 * @Version v1.0
 **/


public class MyTest 
    public static void main(String[] args) 
        ApplicationContext classPathXmlApplicationContext = new ClassPathXmlApplicationContext("applicationcontext.xml");
       // 动态代理代理的是接口，不能写成实现类，故下面这个不行
        UserServiceImpl userService = classPathXmlApplicationContext.getBean("userService", UserServiceImpl.class);
        userService.add();
        System.out.println();
    

正确的写法为：

package com.yang.service;

import org.springframework.context.ApplicationContext;
import org.springframework.context.support.ClassPathXmlApplicationContext;

/**
 * @ClassName MyTest
 * @Author yang
 * @Description //TODO
 * @Date 22/07/23 16:36
 * @Version v1.0
 **/


public class MyTest 
    public static void main(String[] args) 
        ApplicationContext classPathXmlApplicationContext = new ClassPathXmlApplicationContext("applicationcontext.xml");
       // 动态代理代理的是接口，不能写成实现类，故下面这个不行
        UserService userService = classPathXmlApplicationContext.getBean("userService", UserService.class);
        userService.add();
        System.out.println();