Spring+hibernate 配置多数据源

项目中我们经常会遇到多数据源的问题，尤其是数据同步或定时任务等项目更是如此。多数据源让人最头痛的，不是配置多个数据源，而是如何能灵活动态的切换数据源。例如在一个spring和hibernate的框架的项目中，我们在spring配置中往往是配置一个dataSource来连接数据库，然后绑定给sessionFactory，在dao层代码中再指定sessionFactory来进行数据库操作。

正如上图所示，每一块都是指定绑死的，如果是多个数据源，也只能是下图中那种方式。

可看出在Dao层代码中写死了两个SessionFactory，这样日后如果再多一个数据源，还要改代码添加一个SessionFactory，显然这并不符合开闭原则。

那么正确的做法应该是

1. applicationContext.xml如下

<span style="font-size:12px;"><?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: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-3.0.xsd          http://www.springframework.org/schema/context           http://www.springframework.org/schema/context/spring-context-3.0.xsd           http://www.springframework.org/schema/tx     http://www.springframework.org/schema/tx/spring-tx-3.0.xsd           http://www.springframework.org/schema/aop           http://www.springframework.org/schema/aop/spring-aop-3.0.xsd">               <context:annotation-config />    <!-- 隐式地向 Spring 容器注册    AutowiredAnnotationBeanPostProcessor、    CommonAnnotationBeanPostProcessor、    PersistenceAnnotationBeanPostProcessor、    RequiredAnnotationBeanPostProcessor  --><context:component-scan base-package="com.saleSystem,com.interfaces" /><!-- 扫描包中的所有Bean,配置扫描包路径选项 --><tx:annotation-driven transaction-manager="txManager" /><!--@Transactional这个注解进行的驱动，这是基于注解的方式使用事务配置声明 --><bean id="propertyConfigurer"class="org.springframework.beans.factory.config.PropertyPlaceholderConfigurer"><property name="locations"><value>classpath:app/jdbc.properties</value></property></bean><bean id="parentDataSource" class="org.apache.commons.dbcp.BasicDataSource"><property name="driverClassName" value="${jdbc.driverClassName}" /><property name="username" value="${jdbc.username}" /><property name="password" value="${jdbc.password}" />        <property name="initialSize" value="5" />        <property name="maxActive" value="50" />        <property name="maxIdle" value="50" />        <property name="minIdle" value="0" />        <property name="maxWait" value="6000" />        <property name="timeBetweenEvictionRunsMillis" value="60000" />        <property name="minEvictableIdleTimeMillis" value="25200000" /></bean><bean id="adminDataSource" parent="parentDataSource">          <property name="url" value="${jdbc.url}" />    </bean>             <bean id="logDataSource" parent="parentDataSource">          <property name="url" value="${log.url}" />    </bean>  <bean id="dataSource" class="com.datasource.DynamicDataSource">         <property name="targetDataSources">            <map key-type="java.lang.String">               <entry key="logDataSource" value-ref="logDataSource"/>            </map>         </property>         <property name="defaultTargetDataSource" ref="adminDataSource"/>      </bean>  <bean id="sessionFactory"class="org.springframework.orm.hibernate3.annotation.AnnotationSessionFactoryBean"><property name="dataSource" ref="dataSource" /><!-- hibernate 方言 --><property name="hibernateProperties"><props><prop key="hibernate.dialect">org.hibernate.dialect.MySQLDialect</prop><prop key="hibernate.show_sql">true</prop><prop key="javax.persistence.validation.mode">none</prop><prop key="hibernate.format_sql">false</prop><prop key="hibernate.hbm2ddl.auto">validate</prop></props></property><property name="mappingDirectoryLocations"><list><value>classpath:hibernate</value></list></property></bean><bean id="hibernateTemplate" class="org.springframework.orm.hibernate3.HibernateTemplate"><property name="sessionFactory" ref="sessionFactory"></property></bean><bean id="txManager"class="org.springframework.orm.hibernate3.HibernateTransactionManager"><property name="sessionFactory" ref="sessionFactory" /></bean><!-- 面向切面控制权限 --> <aop:config><aop:pointcut expression="execution(public * com.saleSystem.services..*.* (..))"id="bussinessService" /><aop:advisor pointcut-ref="bussinessService" advice-ref="txAdvice" /></aop:config><!-- 谏言 --><!-- 事务 --><tx:advice id="txAdvice" transaction-manager="txManager"><tx:attributes><tx:method name="get*" read-only="true" /><!--以get开头的方法只能从数据库中读取数据  --><tx:method name="find*" read-only="true" /><tx:method name="query*" read-only="true"/>            <tx:method name="load*" propagation="SUPPORTS" />            <tx:method name="search*" propagation="SUPPORTS" />            <tx:method name="datagrid*" propagation="SUPPORTS" />            <tx:method name="add*" propagation="REQUIRED" rollback-for="Exception"/><!--以add开头的方法能对数据库进行查询、新增、删除、编辑1  -->            <tx:method name="edit*" propagation="REQUIRED" rollback-for="Exception"/><tx:method name="save*" propagation="REQUIRED" rollback-for="Exception" /><tx:method name="update*" propagation="REQUIRED" rollback-for="Exception"/><tx:method name="remove*" propagation="REQUIRED" rollback-for="Exception"/><tx:method name="delete*" propagation="REQUIRED" rollback-for="Exception"/>            <tx:method name="modify*" propagation="REQUIRED" rollback-for="Exception"/>            <tx:method name="repair" propagation="REQUIRED" rollback-for="Exception"/>           <tx:method name="deleteAndRepair" propagation="REQUIRED" rollback-for="Exception"/>            <tx:method name="put*" propagation="REQUIRED" rollback-for="Exception"/>            <tx:method name="restart*" propagation="REQUIRED" rollback-for="Exception"/>            <tx:method name="stop*" propagation="REQUIRED" rollback-for="Exception"/>            <tx:method name="change*" propagation="REQUIRED" rollback-for="Exception"/>            <tx:method name="check*" propagation="REQUIRED" rollback-for="Exception"/>            <tx:method name="start*" propagation="REQUIRED" rollback-for="Exception"/>            <tx:method name="porkDiv" propagation="REQUIRED" rollback-for="Exception"/>            <tx:method name="send*" propagation="REQUIRED" rollback-for="Exception"/>            <tx:method name="porkRej" propagation="REQUIRED" rollback-for="Exception"/>            <tx:method name="porkPdtRej" propagation="REQUIRED" rollback-for="Exception"/>            <tx:method name="loginTimeAdd" propagation="REQUIRED" rollback-for="Exception"/>               <tx:method name="productSaleBySaleIdAndType" propagation="REQUIRED" rollback-for="Exception"/>            <tx:method name="sale*" propagation="REQUIRED"/>      </tx:attributes></tx:advice></beans></span>

2. DynamicDataSource.java

import org.springframework.jdbc.datasource.lookup.AbstractRoutingDataSource;public class DynamicDataSource extends AbstractRoutingDataSource {protected Object determineCurrentLookupKey() {return CustomerContextHolder.getCustomerType();}}

3.CustomerContextHolder.java

public class CustomerContextHolder {private static final ThreadLocal contextHolder = new ThreadLocal();public static void setCustomerType(String customerType) {contextHolder.set(customerType);}public static String getCustomerType() {return (String) contextHolder.get();}public static void clearCustomerType() {contextHolder.remove();}}

在《Hibernate 与 Spring 多数据源的配置》中提到

 CustomerContextHolder.setCustomerType(DataSourceMap.Admin);//设置数据源

但是实际运用中，无需再选择数据源，Spring会自动根据不同的Model找到相应的数据源。

另外AbstractRoutingDataSource类也可以实现主从表读写分离，目前还未尝试，但是通过AOP+Annotation即可。

参考：1. 《spring多数据源配置》

    2. 《Hibernate 与 Spring 多数据源的配置》