（2）spring配置文件

<?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:mvc="http://www.springframework.org/schema/mvc" 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/context https://www.springframework.org/schema/context/spring-context.xsd http://www.springframework.org/schema/mvc https://www.springframework.org/schema/mvc/spring-mvc.xsd http://www.springframework.org/schema/tx http://www.springframework.org/schema/tx/spring-tx.xsd">

    <!--springmvc的配置-->
    <context:component-scan base-package="com.ddd"/>



    <!--spring整合mybatis的配置-->

    <!--数据源-->
    <bean id="dataSource" class="com.alibaba.druid.pool.DruidDataSource">
          <property name="driverClassName" value="com.mysql.cj.jdbc.Driver"/>
          <!--mysql驱动为8.0以后必须使用时区-->
          <property name="url" value="jdbc:mysql://localhost:3306/aaa?serverTimezone=Asia/Shanghai"/>
          <property name="username" value="root"/>
          <property name="password" value="root"/>
    </bean>

    <!--spring封装了一个类SqlSessionFactoryBean类，可以把mybatis中的配置-->
    <bean id="sessionFactory" class="org.mybatis.spring.SqlSessionFactoryBean">
          <property name="dataSource" ref="dataSource"/>
          <property name="mapperLocations" value="classpath:/mapper/*.xml"/>
    </bean>

    <!--为指定dao包下的接口生产代理实现类-->
    <bean class="org.mybatis.spring.mapper.MapperScannerConfigurer">
        <property name="sqlSessionFactoryBeanName" value="sessionFactory"/>
        <!--它会为com.ykq.dao包下的所有接口生产代理实现类-->
        <property name="basePackage" value="com.ddd.dao"/>
    </bean>

<!----================以下内容是关于事务的配置===================------>
    <!--事务切面管理器-->
    <bean id="transactionManager" class="org.springframework.jdbc.datasource.DataSourceTransactionManager">
        <property name="dataSource" ref="dataSource"/>
    </bean>

    <!--开启事务管理注解的驱动-->
    <tx:annotation-driven/>
</beans>

(3) dao类和xml

public interface UserDao {
    //1.修改账号余额
    public void updateBalance(@Param("id") int id, @Param("money") double money);
}