最近一个项目用到了多个数据库，所以需要实现动态切换数据源来查询数据，http://www.cnblogs.com/lzrabbit/p/3750803.html这篇文章让我受益匪浅，提供了一种自动切换数据源的思路，但这种方式不支持事务，所以我进一步改进了这个方案，下面直入正题
多数据源配置：
#============================================================================ # DataBaseOne #============================================================================ jdbc.one.driver=com.mysql.jdbc.Driver jdbc.one.url=jdbc:mysql://127.0.0.1:3306/DataBaseOne?useUnicode=true&characterEncoding=UTF-8&allowMultiQueries=true jdbc.one.username=root jdbc.one.password=root ============================================================================= #============================================================================ # DataBaseTwo #============================================================================ jdbc.two.driver=com.mysql.jdbc.Driver jdbc.two.url=jdbc:mysql://127.0.0.1:3306/DataBaseTwo?useUnicode=true&characterEncoding=UTF-8&allowMultiQueries=true jdbc.two.username=root jdbc.two.password=root ============================================================================= #============================================================================ # DataBaseThree #============================================================================ jdbc.three.driver=com.mysql.jdbc.Driver jdbc.three.url=jdbc:mysql://127.0.0.1:3306/DataBaseThree?useUnicode=true&characterEncoding=UTF-8&allowMultiQueries=true jdbc.three.username=root jdbc.mysql.password=root ============================================================================= #============================================================================ # 通用配置 #============================================================================ jdbc.initialSize=5 jdbc.minIdle=5 jdbc.maxIdle=20 jdbc.maxActive=100 jdbc.maxWait=100000 jdbc.defaultAutoCommit=false jdbc.removeAbandoned=true jdbc.removeAbandonedTimeout=600 jdbc.testWhileIdle=true jdbc.timeBetweenEvictionRunsMillis=60000 jdbc.numTestsPerEvictionRun=20 jdbc.minEvictableIdleTimeMillis=300000
Spring中使用多数据源：
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"
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/aop
http://www.springframework.org/schema/aop/spring-aop-3.0.xsd">
<bean id="propertyConfigurer" class="org.springframework.beans.factory.config.PropertyPlaceholderConfigurer">
<property name="location" value="classpath:jdbc.properties"/>
bean>
<bean id="dataSourceOne" class="org.apache.commons.dbcp.BasicDataSource" destroy-method="close">
<property name="driverClassName" value="${jdbc.one.driver}"/>
<property name="url" value="${jdbc.one.url}"/>
<property name="username" value="${jdbc.one.username}"/>
<property name="password" value="${jdbc.one.password}"/>
<property name="initialSize" value="${jdbc.initialSize}"/>
<property name="minIdle" value="${jdbc.minIdle}"/>
<property name="maxIdle" value="${jdbc.maxIdle}"/>
<property name="maxActive" value="${jdbc.maxActive}"/>
<property name="maxWait" value="${jdbc.maxWait}"/>
<property name="defaultAutoCommit" value="${jdbc.defaultAutoCommit}"/>
<property name="removeAbandoned" value="${jdbc.removeAbandoned}"/>
<property name="removeAbandonedTimeout" value="${jdbc.removeAbandonedTimeout}"/>
<property name="testWhileIdle" value="${jdbc.testWhileIdle}"/>
<property name="timeBetweenEvictionRunsMillis" value="${jdbc.timeBetweenEvictionRunsMillis}"/>
<property name="numTestsPerEvictionRun" value="${jdbc.numTestsPerEvictionRun}"/>
<property name="minEvictableIdleTimeMillis" value="${jdbc.minEvictableIdleTimeMillis}"/>
bean>
<bean id="dataSourceTwo" class="org.apache.commons.dbcp.BasicDataSource" destroy-method="close">
<property name="driverClassName" value="${jdbc.two.driver}"/>
<property name="url" value="${jdbc.two.url}"/>
<property name="username" value="${jdbc.two.username}"/>
<property name="password" value="${jdbc.two.password}"/>
<property name="initialSize" value="${jdbc.initialSize}"/>
<property name="minIdle" value="${jdbc.minIdle}"/>
<property name="maxIdle" value="${jdbc.maxIdle}"/>
<property name="maxActive" value="${jdbc.maxActive}"/>
<property name="maxWait" value="${jdbc.maxWait}"/>
<property name="defaultAutoCommit" value="${jdbc.defaultAutoCommit}"/>
<property name="removeAbandoned" value="${jdbc.removeAbandoned}"/>
<property name="removeAbandonedTimeout" value="${jdbc.removeAbandonedTimeout}"/>
<property name="testWhileIdle" value="${jdbc.testWhileIdle}"/>
<property name="timeBetweenEvictionRunsMillis" value="${jdbc.timeBetweenEvictionRunsMillis}"/>
<property name="numTestsPerEvictionRun" value="${jdbc.numTestsPerEvictionRun}"/>
<property name="minEvictableIdleTimeMillis" value="${jdbc.minEvictableIdleTimeMillis}"/>
bean>
<bean id="dataSourceThree" class="org.apache.commons.dbcp.BasicDataSource" destroy-method="close">
<property name="driverClassName" value="${jdbc.three.driver}"/>
<property name="url" value="${jdbc.three.url}"/>
<property name="username" value="${jdbc.three.username}"/>
<property name="password" value="${jdbc.three.password}"/>
<property name="initialSize" value="${jdbc.initialSize}"/>
<property name="minIdle" value="${jdbc.minIdle}"/>
<property name="maxIdle" value="${jdbc.maxIdle}"/>
<property name="maxActive" value="${jdbc.maxActive}"/>
<property name="maxWait" value="${jdbc.maxWait}"/>
<property name="defaultAutoCommit" value="${jdbc.defaultAutoCommit}"/>
<property name="removeAbandoned" value="${jdbc.removeAbandoned}"/>
<property name="removeAbandonedTimeout" value="${jdbc.removeAbandonedTimeout}"/>
<property name="testWhileIdle" value="${jdbc.testWhileIdle}"/>
<property name="timeBetweenEvictionRunsMillis" value="${jdbc.timeBetweenEvictionRunsMillis}"/>
<property name="numTestsPerEvictionRun" value="${jdbc.numTestsPerEvictionRun}"/>
<property name="minEvictableIdleTimeMillis" value="${jdbc.minEvictableIdleTimeMillis}"/>
bean>
<bean id="multipleDataSource" class="com.cnblogs.datasource.MultipleDataSource">
<property name="defaultTargetDataSource" ref="dataSourceOne"/>
<property name="targetDataSources">
<map>
<entry key="dataSourceOneKey" value-ref="dataSourceOne"/>
<entry key="dataSourceTwoKey" value-ref="dataSourceTwo"/>
<entry key="dataSourceThreeKey" value-ref="dataSourceThree"/>
map>
property>
bean>
<bean id="sqlSessionFactory" class="org.mybatis.spring.SqlSessionFactoryBean">
<property name="dataSource" ref="multipleDataSource"/>
bean>
<bean class="org.mybatis.spring.mapper.MapperScannerConfigurer">
<property name="basePackage" value="com.cnblogs.mapper"/>
bean>
<context:component-scan base-package="com.cnblogs.**"/>
<aop:config>
<aop:pointcut id="myPointcut"
expression="execution(* com.cnblogs.service.*.*(..))" />
<aop:advisor advice-ref="txAdvice" pointcut-ref="myPointcut" />
aop:config>
beans>
MultipleDataSource.java实现：
package com.cnblogs.datasource; import org.springframework.jdbc.datasource.lookup.AbstractRoutingDataSource; /** 多数据源java实现 */ public class MultipleDataSource extends AbstractRoutingDataSource { private static final ThreadLocaldataSourceKey = new InheritableThreadLocal (); public static void setDataSourceKey(String dataSource) { dataSourceKey.set(dataSource); } @Override protected Object determineCurrentLookupKey() { return dataSourceKey.get(); } }
下面详解使用SpringAOP来实现数据源切换，并支持事务控制
上面我们配置的AOP是针对service层的，所以在调用service层的任何方法时都会经过AOP，因此我们就在AOP中先于service调用时把数据源切换，看代码
新建类MultipleDataSourceAspectAdvice，把MultipleDataSourceAspectAdvice.java放在spring能自动注入的包中，比如controller包，或者自己把这个类所在的包加入到component-scan配置中去，总之要要让spring能自动加载
package com.cnblogs.controller; import org.apache.log4j.Logger; import org.aspectj.lang.ProceedingJoinPoint; import org.aspectj.lang.annotation.Around; import org.aspectj.lang.annotation.Aspect; import org.aspectj.lang.annotation.Pointcut; import org.springframework.core.annotation.Order; import org.springframework.stereotype.Component; import com.cnblogs.datasource.MultipleDataSource; import com.cnblogs.service.DataBaseOne; import com.cnblogs.service.DataBaseTwo; import com.cnblogs.service.DataBaseThree; /** * 数据库链接自动切换AOP处理 * Order优先级设置到最高，因为在所有service方法调用前都必须把数据源确定 * Order数值越小优先级越高 */ @Component @Aspect @Order(1) public class MultipleDataSourceAspectAdvice { private static final Logger LOGGER = Logger.getLogger(MultipleDataSourceAspectAdvice.class); public MultipleDataSourceAspectAdvice() { LOGGER.info("MultipleDataSourceAspectAdvice 加载成功"); } /** * 定义切面 */ @Pointcut("execution(* com.cnblogs.service.*.*(..))") public void pointCut() { } // dataSourceOneKey // dataSourceTwoKey // dataSourceThreeKey @Around("pointCut()") public Object doAround(ProceedingJoinPoint jp) throws Throwable { if (jp.getTarget() instanceof DataBaseOne) { LOGGER.debug("使用数据库链接：dataSourceOneKey"); MultipleDataSource.setDataSourceKey("dataSourceOneKey"); } else if (jp.getTarget() instanceof DataBaseTwo) { LOGGER.debug("使用数据库链接：dataSourceTwoKey"); MultipleDataSource.setDataSourceKey("dataSourceTwoKey"); } else if (jp.getTarget() instanceof DataBaseThree) { LOGGER.debug("使用数据库链接：dataSourceThreeKey"); MultipleDataSource.setDataSourceKey("dataSourceThreeKey"); } else { // 默认是dataSourceOneKey LOGGER.debug("使用数据库链接：dataSourceOneKey"); MultipleDataSource.setDataSourceKey("dataSourceOneKey"); } return jp.proceed(); } }
到这里我们所以的spring多数据源配置已经完毕，那如何在执行service方法时让service切换到正确的数据库呢？上面的类中定义了有3个类DataBaseOne，DataBaseTwo，DataBaseThree，这3个类其实只是一个interface，没有任何实现方法，我们让具体业务的service都继承至这3个类以区分不同的service对应不同的数据源，因为业务的service我是知道他用的哪个数据源的，比如FooService继承至DataBaseOne，则在使用FooService任何方法时AOP就会先把数据源切换到dataSourceOneKey，以此就达到了自动切换数据源的目的，并且支持事务，下面看代码：
package com.cnblogs.service; /** * DataBaseOne数据库占位类 * 详情参见 MultipleDataSourceAspectAdvice 类 */ public interface DataBaseOne { }
DataBaseTwo，DataBaseThree与这完全相同
至此多数据源就配置完毕，可以安心写业务逻辑了
原理部分博友http://www.cnblogs.com/lzrabbit/p/3750803.html讲的十分清楚，再次感谢