SSM项目的spring-mybatis.xml

<?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:p="http://www.springframework.org/schema/p"      xmlns:context="http://www.springframework.org/schema/context"      xmlns:mvc="http://www.springframework.org/schema/mvc"      xsi:schemaLocation="http://www.springframework.org/schema/beans                            http://www.springframework.org/schema/beans/spring-beans-3.1.xsd                            http://www.springframework.org/schema/context                            http://www.springframework.org/schema/context/spring-context-3.1.xsd                            http://www.springframework.org/schema/mvc                            http://www.springframework.org/schema/mvc/spring-mvc-4.0.xsd">      <!-- 自动扫描(扫描的什么，有什么作用，为什么需要扫描？？？) -->      <context:component-scan base-package="com.iot.modul" />          <!-- 引入配置文件 -->      <bean id="propertyConfigurer"          class="org.springframework.beans.factory.config.PropertyPlaceholderConfigurer">         <!--  这里的classpath是谁在哪里定义的？？？ -->        <property name="location" value="classpath:jdbc.properties" />      </bean>            <!--  如何与jdbc.properties联系上的？？？ -->    <bean id="dataSource" class="org.apache.commons.dbcp.BasicDataSource"          destroy-method="close">          <property name="driverClassName" value="${driver}" />          <property name="url" value="${url}" />          <property name="username" value="${username}" />          <property name="password" value="${password}" />          <!-- 初始化连接大小 -->          <property name="initialSize" value="${initialSize}"></property>          <!-- 连接池最大数量 -->          <property name="maxActive" value="${maxActive}"></property>          <!-- 连接池最大空闲 -->          <property name="maxIdle" value="${maxIdle}"></property>          <!-- 连接池最小空闲 -->          <property name="minIdle" value="${minIdle}"></property>          <!-- 获取连接最大等待时间 -->          <property name="maxWait" value="${maxWait}"></property>      </bean>       <!-- spring和MyBatis完美整合，不需要mybatis的配置映射文件 -->      <bean id="sqlSessionFactory" class="org.mybatis.spring.SqlSessionFactoryBean">          <property name="dataSource" ref="dataSource" />          <!-- 自动扫描mapping.xml文件 -->          <property name="mapperLocations" value="classpath:com/iot/modul/mapping/*.xml"></property>      </bean>       <!-- DAO接口所在包名，Spring会自动查找其下的类 -->      <bean class="org.mybatis.spring.mapper.MapperScannerConfigurer">          <property name="basePackage" value="com.iot.modul.dao" />          <property name="sqlSessionFactoryBeanName" value="sqlSessionFactory"></property>      </bean>       <!-- (事务管理)transaction manager, use JtaTransactionManager for global tx -->      <bean id="transactionManager"          class="org.springframework.jdbc.datasource.DataSourceTransactionManager">          <property name="dataSource" ref="dataSource" />      </bean>   </beans>