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
代码如下：
1. applicationContext.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:aop="http://www.springframework.org/schema/aop"
- xmlns:cache="http://www.springframework.org/schema/cache"
- xmlns:context="http://www.springframework.org/schema/context"
- xmlns:jdbc="http://www.springframework.org/schema/jdbc" xmlns:jee="http://www.springframework.org/schema/jee"
- xmlns:jms="http://www.springframework.org/schema/jms" xmlns:lang="http://www.springframework.org/schema/lang"
- xmlns:mvc="http://www.springframework.org/schema/mvc" xmlns:oxm="http://www.springframework.org/schema/oxm"
- xmlns:p="http://www.springframework.org/schema/p" xmlns:task="http://www.springframework.org/schema/task"
- xmlns:tx="http://www.springframework.org/schema/tx" xmlns:util="http://www.springframework.org/schema/util"
- xsi:schemaLocation="http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans.xsd
- http://www.springframework.org/schema/aop http://www.springframework.org/schema/aop/spring-aop-3.1.xsd
- http://www.springframework.org/schema/cache http://www.springframework.org/schema/cache/spring-cache-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/jdbc http://www.springframework.org/schema/jdbc/spring-jdbc-3.1.xsd
- http://www.springframework.org/schema/jee http://www.springframework.org/schema/jee/spring-jee-3.1.xsd
- http://www.springframework.org/schema/jms http://www.springframework.org/schema/jms/spring-jms-3.1.xsd
- http://www.springframework.org/schema/lang http://www.springframework.org/schema/lang/spring-lang-3.1.xsd
- http://www.springframework.org/schema/mvc http://www.springframework.org/schema/mvc/spring-mvc-3.1.xsd
- http://www.springframework.org/schema/oxm http://www.springframework.org/schema/oxm/spring-oxm-3.1.xsd
- http://www.springframework.org/schema/task http://www.springframework.org/schema/task/spring-task-3.1.xsd
- http://www.springframework.org/schema/tx http://www.springframework.org/schema/tx/spring-tx-3.1.xsd
- http://www.springframework.org/schema/util http://www.springframework.org/schema/util/spring-util-3.1.xsd">
- <context:annotation-config />
- <context:component-scan base-package="com"></context:component-scan>
- <bean class="org.springframework.beans.factory.config.PropertyPlaceholderConfigurer">
- <property name="locations">
- <list>
- <value>classpath:com/resource/config.properties</value>
- </list>
- </property>
- </bean>
- <bean id="dataSourceOne" class="com.mchange.v2.c3p0.ComboPooledDataSource"
- destroy-method="close">
- <property name="driverClass" value="${dbOne.jdbc.driverClass}" />
- <property name="jdbcUrl" value="${dbOne.jdbc.url}" />
- <property name="user" value="${dbOne.jdbc.user}" />
- <property name="password" value="${dbOne.jdbc.password}" />
- <property name="initialPoolSize" value="${dbOne.jdbc.initialPoolSize}" />
- <property name="minPoolSize" value="${dbOne.jdbc.minPoolSize}" />
- <property name="maxPoolSize" value="${dbOne.jdbc.maxPoolSize}" />
- </bean>
- <bean id="dataSourceTwo" class="com.mchange.v2.c3p0.ComboPooledDataSource"
- destroy-method="close">
- <property name="driverClass" value="${dbTwo.jdbc.driverClass}" />
- <property name="jdbcUrl" value="${dbTwo.jdbc.url}" />
- <property name="user" value="${dbTwo.jdbc.user}" />
- <property name="password" value="${dbTwo.jdbc.password}" />
- <property name="initialPoolSize" value="${dbTwo.jdbc.initialPoolSize}" />
- <property name="minPoolSize" value="${dbTwo.jdbc.minPoolSize}" />
- <