java.lang.ClassCastException: com.sun.proxy.$Proxy13 cannot be cast to sm.dao.UserDao

在Spring中添加事物管理以后出现的问题

源代码

ApplicationContext applicationContext = new ClassPathXmlApplicationContext("applicationContext.xml");

UserDao userDao = (UserDao) applicationContext.getBean("UserDao");

 错误原因对于Spring AOP 采用两种代理方法，一种是常规JDK，一种是CGLIB，我的UserDao了一个接口IUserDao，当代理对象实现了至少一个接口时，默认使用JDK动态创建代理对象，当代理对象没有实现任何接口时，就会使用CGLIB方法。具体介绍文章 

解决方法：

因为基于JDK的代理是面向接口的，所以我们自己修改代码如下

   ApplicationContext applicationContext = new ClassPathXmlApplicationContext("applicationContext.xml");

    IUserDao userDao = (IUserDao) applicationContext.getBean("UserDao");

附上applicationContext.xml配置

<?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:jdbc="http://www.springframework.org/schema/jdbc"

       xmlns:tx="http://www.springframework.org/schema/tx"

       xsi:schemaLocation="http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans.xsd http://www.springframework.org/schema/jdbc http://www.springframework.org/schema/jdbc/spring-jdbc.xsd http://www.springframework.org/schema/tx http://www.springframework.org/schema/tx/spring-tx.xsd">



    <bean id="dataSoure" class="org.apache.commons.dbcp.BasicDataSource">

        <property name="driverClassName" value="com.mysql.jdbc.Driver"></property>

        <property name="url" value="jdbc:mysql://localhost:3306/sm"></property>

        <property name="username" value="root"></property>

        <property name="password" value="genji"></property>



    </bean>

    <bean id="sessionFactory" class="org.springframework.orm.hibernate4.LocalSessionFactoryBean">

        <property name="dataSource">

            <ref bean="dataSoure"></ref>

        </property>

        <property name="hibernateProperties">

            <props>

                <prop key="hibernate.dialect">

                    org.hibernate.dialect.MySQL5Dialect



                </prop>

                <prop key="hibernate.current_session_context_class">

                    org.springframework.orm.hibernate4.SpringSessionContext

                </prop>





            </props>





        </property>

        <property name="mappingResources">





            <list>

                <value>sm/po/Studentinfo.hbm.xml</value>

                <value>sm/po/User.hbm.xml</value>

            </list>

        </property>





    </bean>

    <bean id="UserDao" class="sm.dao.UserDao">

        <property name="sessionFactory">

            <ref bean="sessionFactory"></ref>

        </property>





    </bean>

    <bean id="SinfoDao" class="sm.dao.SinfoDao">

        <property name="sessionFactory">

            <ref bean="sessionFactory"></ref>



        </property>





    </bean>
//就是在这里实现了事务代理


    <bean id="txManager"

          class="org.springframework.orm.hibernate4.HibernateTransactionManager">

        <property name="sessionFactory" ref="sessionFactory" />

    </bean>

    <tx:annotation-driven />

    <tx:advice id="txAdvice" transaction-manager="txManager">

        <tx:attributes>

            <tx:method name="add" read-only="true" propagation="REQUIRED" />

            <tx:method name="read" propagation="REQUIRED" />

            <tx:method name="del" propagation="REQUIRED" />

            <tx:method name="mod" propagation="REQUIRED" />

            <tx:method name="sameId" propagation="REQUIRED" />

            <tx:method name="findUser" propagation="REQUIRED"/>

            <tx:method name="addUser" propagation="REQUIRED"></tx:method>

        </tx:attributes>

    </tx:advice>



</beans>

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