改造原有的專案 實現讀寫分離

準備工作：
1.需要一個能夠執行的spring + mybatis的專案
2.mysql 主從資料庫

• 拆分Dao（按照讀寫去拆分）
  

• 拆分mapping檔案
  

• 新增資料庫配置檔案（jdbc.properties）
  

• *呼叫（需要用哪個就在service中注入相應的dao）
  

• 修改applicationContenxt.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:tx="http://www.springframework.org/schema/tx"
    xmlns:aop="http://www.springframework.org/schema/aop"
    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/tx
                        http://www.springframework.org/schema/tx/spring-tx-4.0.xsd
                        http://www.springframework.org/schema/aop
                        http://www.springframework.org/schema/aop/spring-aop-4.0.xsd
                        http://www.springframework.org/schema/mvc
                        http://www.springframework.org/schema/mvc/spring-mvc-4.0.xsd"
 
>  
    <!-- 自動掃描 -->  
    <context:component-scan base-package="com.pkl.dubbo" />  
    <!-- 引入配置檔案 -->  
    <bean id="propertyConfigurer"  
        class="org.springframework.beans.factory.config.PropertyPlaceholderConfigurer"> 
        <property name="locations">
            <list
 
>
                <value>classpath:jdbc.properties</value>
                <value>classpath:redis.properties</value>
            </list>
        </property>
    </bean>  
    <bean id="masterDataSource" class="com.alibaba.druid.pool.DruidDataSource" init-method="init" destroy-method="close">
        <property name="url" value="${url}" />
        <property name="username" value="${username}" />
        <property name="password" value="${password}" />
        <!--初始化連線大小   -->
         <property name="initialSize" value="${initialSize}"></property>
<!--         連線池最大數量   -->
        <property name="maxActive" value="${maxActive}"></property>  
<!--         連線池最大空閒   -->
        <property name="maxIdle" value="${maxIdle}"></property>  
<!--         連線池最小空閒   -->
        <property name="minIdle" value="${minIdle}"></property>  
<!--         獲取連線最大等待時間   -->
        <property name="maxWait" value="${maxWait}"></property>  
        <!-- 配置間隔多久才進行一次檢測，檢測需要關閉的空閒連線，單位是毫秒 -->
        <property name="timeBetweenEvictionRunsMillis" value="60000" />
        <!-- 配置一個連線在池中最小生存的時間，單位是毫秒 -->
        <property name="minEvictableIdleTimeMillis" value="300000" />
        <property name="validationQuery" value="SELECT 'x'" />
        <property name="testWhileIdle" value="true" />
        <property name="testOnBorrow" value="false" />
        <property name="testOnReturn" value="false" />
        <!-- 開啟PSCache，並且制定每個連線PSCache的大小 -->
        <property name="poolPreparedStatements" value="true" />
        <property name="maxPoolPreparedStatementPerConnectionSize" value="50" />
        <!-- 配置監控統計攔截的filters，去掉後監控介面的sql無法統計      加log4j 是為了打印出獲取conn和回收conn的log-->
        <property name="filters" value="stat,log4j" />
    </bean>
    <bean id="slaveDataSource" class="com.alibaba.druid.pool.DruidDataSource" init-method="init" destroy-method="close">
        <property name="url" value="${slave_url}" />
        <property name="username" value="${slave_username}" />
        <property name="password" value="${slave_password}" />
         <property name="initialSize" value="${initialSize}"></property>
        <property name="maxActive" value="${maxActive}"></property>  
        <property name="maxIdle" value="${maxIdle}"></property>  
        <property name="minIdle" value="${minIdle}"></property>  
        <property name="maxWait" value="${maxWait}"></property>  
        <property name="timeBetweenEvictionRunsMillis" value="60000" />
        <property name="minEvictableIdleTimeMillis" value="300000" />
        <property name="validationQuery" value="SELECT 'x'" />
        <property name="testWhileIdle" value="true" />
        <property name="testOnBorrow" value="false" />
        <property name="testOnReturn" value="false" />
        <property name="poolPreparedStatements" value="true" />
        <property name="maxPoolPreparedStatementPerConnectionSize" value="50" />
        <property name="filters" value="stat,log4j" />
    </bean>
    <!-- (事務管理)transaction manager, use JtaTransactionManager for global tx -->  
    <bean id="masterTransactionManager"  
        class="org.springframework.jdbc.datasource.DataSourceTransactionManager">  
        <property name="dataSource" ref="masterDataSource" />  
    </bean>
    <bean id="masterTransactionTemplate"
        class="org.springframework.transaction.support.TransactionTemplate">
        <property name="transactionManager" ref="masterTransactionManager" />
    </bean>

    <!-- spring和MyBatis完美整合，不需要mybatis的配置對映檔案   -->
    <bean id="masterSessionFactory" class="org.mybatis.spring.SqlSessionFactoryBean">  
        <property name="dataSource" ref="masterDataSource" />  
        <!-- 自動掃描mapping.xml檔案 -->  
        <property name="mapperLocations" value="classpath:mapping/write/*.xml"></property>  
        <property name="plugins">
            <array>
                <ref bean="sqlStatementInterceptor"/>
            </array>
        </property>
    </bean>  

     <bean id="sqlStatementInterceptor" class="com.pkl.dubbo.interceptor.MybatisInterceptor"></bean>

    <!-- DAO介面所在包名，Spring會自動查詢其下的類 -->  
    <bean class="org.mybatis.spring.mapper.MapperScannerConfigurer">  
        <property name="basePackage" value="com.pkl.dubbo.dao.write" />  
        <property name="sqlSessionFactoryBeanName" value="masterSessionFactory"></property>  
    </bean>  

    <!-- slave -->
    <bean id="slaveTransactionManager"  
        class="org.springframework.jdbc.datasource.DataSourceTransactionManager">  
        <property name="dataSource" ref="slaveDataSource" />  
    </bean>
    <bean id="slaveTransactionTemplate"
        class="org.springframework.transaction.support.TransactionTemplate">
        <property name="transactionManager" ref="slaveTransactionManager" />
    </bean>
    <bean id="slaveSessionFactory" class="org.mybatis.spring.SqlSessionFactoryBean">  
        <property name="dataSource" ref="slaveDataSource" />  
        <property name="mapperLocations" value="classpath:mapping/read/*.xml"></property>
        <property name="plugins">
            <array>
                <ref bean="sqlStatementInterceptor"/>
            </array>
        </property>  
    </bean>  
    <bean class="org.mybatis.spring.mapper.MapperScannerConfigurer">  
        <property name="basePackage" value="com.pkl.dubbo.dao.read" />  
        <property name="sqlSessionFactoryBeanName" value="slaveSessionFactory"></property>  
    </bean>  
    <!-- Configuration transaction advice -->
      <tx:advice id="txAdvice" transaction-manager="masterTransactionManager">
        <tx:attributes>
          <tx:method name="add*" propagation="REQUIRED" />
          <tx:method name="update*" propagation="REQUIRED" />
          <tx:method name="delete*" propagation="REQUIRED" />
          <tx:method name="get*" read-only="true" propagation="SUPPORTS" />
          <tx:method name="list*" read-only="true" propagation="SUPPORTS" />
        </tx:attributes>
      </tx:advice>
      <!-- Configuration transaction aspect -->
      <aop:config>
        <aop:pointcut id="systemServicePointcut"
          expression="execution(* com.pkl.dubbo.service.*.*(..))" />
        <aop:advisor advice-ref="txAdvice" pointcut-ref="systemServicePointcut" />
      </aop:config>
</beans>

• *我使用的連線池是Druid(以下是依賴資訊)

<!-- alibaba DB connection Pool -->
        <dependency>
            <groupId>com.alibaba</groupId>
            <artifactId>druid</artifactId>
            <version>1.0.16</version>
        </dependency>