mybatis和springMVC整合及其中的問題

1. springMVC+spring+mybatis的整合大體結構：

（1）config/mybatis/SqlMapConfig.xml中放置mybatis的配置文件，因爲這個例子很簡單，因此配置得比較簡單。在spring與mybatis的整合中，在這裏不用配置mapper，由於在mybatis-spring整合jar包中有mapper的掃描類。

<?xml version="1.0" encoding="UTF-8" ?>
<!DOCTYPE configuration
        PUBLIC "-//mybatis.org//DTD Config 3.0//EN"
        "http://mybatis.org/dtd/mybatis-3-config.dtd">
<configuration>
</configuration>

（2）config/spring/appliacationContext.xml中配置的是mybatis和spring整合的配置。其中包括數據源（數據池）的配置、sqlSessionFactory的配置、mapper掃描器的配置還有事務的配置。目前aop還不是很會，因此事務配置並無在程序中體現。

<?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:aop="http://www.springframework.org/schema/aop"
        xmlns:tx="http://www.springframework.org/schema/tx"
        xsi:schemaLocation="http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans-3.1.xsd
    http://www.springframework.org/schema/aop http://www.springframework.org/schema/aop/spring-aop-3.1.xsd
    http://www.springframework.org/schema/tx http://www.springframework.org/schema/tx/spring-tx-3.1.xsd
    " default-autowire="byName">
    <!-- 讀取配置文件 -->
    <bean id="config" class="org.springframework.beans.factory.config.PropertyPlaceholderConfigurer">
        <property name="locations">
            <list>
                <value>classpath:db.properties</value>
            </list>
        </property>
    </bean>
    <!-- 配置數據庫鏈接池 -->
    <bean id="dataSource" class="com.mchange.v2.c3p0.ComboPooledDataSource">
        <property name="user" value="${username}"/>
        <property name="password" value="${password}"/>
        <property name="driverClass" value="${driverClassName}"/>
        <property name="jdbcUrl" value="${jdbcUrl}"/>
        <!--<property name="acquireIncrement" value="${c3p0.acquireIncrement}"/>-->
        <property name="acquireIncrement" value="${c3p0.acquireIncrement}"/>
        <property name="initialPoolSize" value="${c3p0.initialPoolSize}"/>
        <property name="minPoolSize" value="${c3p0.minPoolSize}"/>
        <property name="maxPoolSize" value="${c3p0.maxPoolSize}"/>
        <property name="maxIdleTime" value="${c3p0.maxIdleTime}"/>
        <property name="idleConnectionTestPeriod" value="${c3p0.idleConnectionTestPeriod}"/>
        <property name="maxStatements" value="${c3p0.maxStatements}"/>
        <property name="numHelperThreads" value="${c3p0.numHelperThreads}"/>
    </bean>
    <!-- 配置sqlSessionFactory -->
    <bean id="mySqlSessionFactory" class="org.mybatis.spring.SqlSessionFactoryBean">
        <property name="dataSource" ref="dataSource"/>
        <property name="configLocation" value="classpath:mybatis/SqlMapConfig.xml"/>
    </bean>

    <bean class="org.mybatis.spring.mapper.MapperScannerConfigurer">
        <property name="basePackage" value="com.hggggc.ssm.mapper"/>
        <property name="sqlSessionFactoryBeanName" value="mySqlSessionFactory"/>

    </bean>

    <bean class="com.hggggc.ssm.service.DeptServiceImpl" id="deptService"/>

    <bean id="transactionManager" class="org.springframework.jdbc.datasource.DataSourceTransactionManager">
        <property name="dataSource" ref="dataSource"/>
    </bean>
    
    <!--<tx:advice id="Txadvice" transaction-manager="transactionManager">-->
        <!--<tx:attributes>-->
            <!--<tx:method name="save" propagation="REQUIRED"/>-->
            <!--<tx:method name="delete" propagation="REQUIRED"/>-->
            <!--<tx:method name="insert" propagation="REQUIRED"/>-->
            <!--<tx:method name="update" propagation="REQUIRED"/>-->
            <!--<tx:method name="find" propagation="SUPPORTS" read-only="true"/>-->
        <!--</tx:attributes>-->
    <!--</tx:advice>-->

    <!--<aop:config>-->
        <!--<aop:advisor advice-ref="Txadvice" pointcut="execution(* com.hggggc.ssm.service.*.*(..))"/>-->
    <!--</aop:config>-->
</beans> 

（3）config/spring/springMVC.xml配置的就是springMVC框架所用到的處理器映射器。 

<?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"
       xmlns:task="http://www.springframework.org/schema/task"
       xmlns:tx="http://www.springframework.org/schema/tx"
       xmlns:apop="http://www.springframework.org/schema/aop"
       xsi:schemaLocation="
        http://www.springframework.org/schema/beans
        http://www.springframework.org/schema/beans/spring-beans-3.2.xsd
        http://www.springframework.org/schema/context
        http://www.springframework.org/schema/context/spring-context-3.2.xsd
        http://www.springframework.org/schema/mvc
        http://www.springframework.org/schema/mvc/spring-mvc-3.2.xsd
        http://www.springframework.org/schema/aop
        http://www.springframework.org/schema/mvc/spring-aop-3.2.xsd
        http://www.springframework.org/schema/tx
        http://www.springframework.org/schema/mvc/spring-tx-3.2.xsd
        http://www.springframework.org/schema/task
        http://www.springframework.org/schema/task/spring-task-3.2.xsd">
    <!--視圖解析器-->
    <bean class="org.springframework.web.servlet.view.InternalResourceViewResolver"/>
    <!--3.1後的配置-->
    <bean class="org.springframework.web.servlet.mvc.method.annotation.RequestMappingHandlerMapping"/>
    <bean class="org.springframework.web.servlet.mvc.method.annotation.RequestMappingHandlerAdapter"/>   
    <!--掃描組件-->
    <context:component-scan base-package="com.hggggc.ssm.controller"></context:component-scan>
</beans>    

（4）db.properties裏面配置了 數據庫驅動所需的各類屬性包括：驅動類名、用戶名、密碼等還有數據池的屬性

driverClassName=com.mysql.jdbc.Driver
jdbcUrl=jdbc:mysql://localhost:3306/mydb1?rewriteBatchedStatements=true
username=root
password=1234

c3p0.acquireIncrement=3
c3p0.initialPoolSize=3
c3p0.idleConnectionTestPeriod=60
c3p0.minPoolSize=5
c3p0.maxPoolSize=100
c3p0.maxStatements=100
c3p0.numHelperThreads=10
c3p0.maxIdleTime=60

（5）log4j.properties是log的配置文件，不太懂。

（6）有關web.xml的配置

<?xml version="1.0" encoding="UTF-8"?>
<web-app xmlns="http://xmlns.jcp.org/xml/ns/javaee"
         xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
         xsi:schemaLocation="http://xmlns.jcp.org/xml/ns/javaee http://xmlns.jcp.org/xml/ns/javaee/web-app_3_1.xsd"
         version="3.1">

    <context-param>
        <param-name>contextConfigLocation</param-name>
        <param-value>classpath:spring/*.xml</param-value>
    </context-param>
<listener>
    <listener-class>org.springframework.web.context.ContextLoaderListener</listener-class>
</listener>
    <servlet>
        <servlet-name>springMVC</servlet-name>
        <servlet-class>org.springframework.web.servlet.DispatcherServlet</servlet-class>
        <init-param>
            <param-name>contextConfigLocation</param-name>
            <param-value>classpath:spring/springMVC.xml</param-value>
        </init-param>
    </servlet>
    
    <servlet-mapping>
        <servlet-name>springMVC</servlet-name>
        <url-pattern>*.action</url-pattern>
    </servlet-mapping>
</web-app>

接下來只需寫：

（1）mapper文件：mapper.java文件和mapper.xml文件同名同目錄（dao）

（2）service：寫service接口，並實現，最後配置。在實現類中注入mapper，此時會報錯，由於還沒掃描，並不影響程序運行。

<bean class="com.hggggc.ssm.service.DeptServiceImpl" id="deptService"/> 

（3）controller（handler）：在其中注入service

2.spring+mybatis 報Could not load driverClass ${jdbc.driverClass}

<!-- 配置sqlSessionFactory -->
<bean id="sqlSessionFactory" class="org.mybatis.spring.SqlSessionFactoryBean">
    <property name="dataSource" ref="dataSource"/>
    <property name="configLocation" value="classpath:mybatis/SqlMapConfig.xml"/>
</bean>
<bean class="org.mybatis.spring.mapper.MapperScannerConfigurer">
    <property name="basePackage" value="com.hggggc.ssm.mapper"/>
    <property name="sqlSessionFactoryBeanName" value="sqlSessionFactory"/>
</bean>

改成

<!-- 配置sqlSessionFactory -->
<bean id="mySqlSessionFactory" class="org.mybatis.spring.SqlSessionFactoryBean">
    <property name="dataSource" ref="dataSource"/>
    <property name="configLocation" value="classpath:mybatis/SqlMapConfig.xml"/>
</bean>
<bean class="org.mybatis.spring.mapper.MapperScannerConfigurer">
    <property name="basePackage" value="com.hggggc.ssm.mapper"/>
    <property name="sqlSessionFactoryBeanName" value="mySqlSessionFactory"/>
</bean>

在spring裏使用org.mybatis.spring.mapper.MapperScannerConfigurer 進行自動掃描的時候，設置了sqlSessionFactory 的話，可能會致使PropertyPlaceholderConfigurer失效，也就是用${jdbc.username}這樣之類的表達式，將沒法獲取到properties文件裏的內容。 致使這一緣由是由於，MapperScannerConigurer實際是在解析加載bean定義階段的，這個時候要是設置sqlSessionFactory的話，會致使提早初始化一些類，這個時候，PropertyPlaceholderConfigurer還沒來得及替換定義中的變量，致使把表達式看成字符串複製了。 因此將id改了就解決問題了