关于双数据源的切换问题
之前让配置一个双数据源，然后在不同的地方调用不同的数据源问题，通过上网查询最终解决了问题，但是在切换数据源的地方卡了一下，在这里主要阐述一下双数据的切换（配置文件方式切换）
先看网上的一个例子（引用地址http://blog.csdn.net/wangpeng047/article/details/8866239 ，里面还有demo下载 ）
<?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-4.1.xsd http://www.springframework.org/schema/aop http://www.springframework.org/schema/aop/spring-aop-4.1.xsd http://www.springframework.org/schema/cache http://www.springframework.org/schema/cache/spring-cache-4.1.xsd http://www.springframework.org/schema/context http://www.springframework.org/schema/context/spring-context-4.1.xsd http://www.springframework.org/schema/jdbc http://www.springframework.org/schema/jdbc/spring-jdbc-4.1.xsd http://www.springframework.org/schema/jee http://www.springframework.org/schema/jee/spring-jee-4.1.xsd http://www.springframework.org/schema/jms http://www.springframework.org/schema/jms/spring-jms-4.1.xsd http://www.springframework.org/schema/lang http://www.springframework.org/schema/lang/spring-lang-4.1.xsd http://www.springframework.org/schema/mvc http://www.springframework.org/schema/mvc/spring-mvc-4.1.xsd http://www.springframework.org/schema/oxm http://www.springframework.org/schema/oxm/spring-oxm-4.1.xsd http://www.springframework.org/schema/task http://www.springframework.org/schema/task/spring-task-4.1.xsd http://www.springframework.org/schema/tx http://www.springframework.org/schema/tx/spring-tx-4.1.xsd http://www.springframework.org/schema/util http://www.springframework.org/schema/util/spring-util-4.1.xsd"> <context:annotation-config /> <aop:aspectj-autoproxy /> <context:component-scan base-package="com"> <context:exclude-filter type="annotation" expression="org.springframework.stereotype.Controller" /> </context:component-scan> <context:property-placeholder location="classpath:com/resources/datasource.properties" /> <bean id="dataSourceMySql" class="com.mchange.v2.c3p0.ComboPooledDataSource" destroy-method="close"> <property name="driverClass" value="${mysql.jdbc.driverClass}" /> <property name="jdbcUrl" value="${mysql.jdbc.url}" /> <property name="user" value="${mysql.jdbc.user}" /> <property name="password" value="${mysql.jdbc.password}" /> <property name="initialPoolSize" value="${mysql.jdbc.initialPoolSize}" /> <property name="minPoolSize" value="${mysql.jdbc.minPoolSize}" /> <property name="maxPoolSize" value="${mysql.jdbc.maxPoolSize}" /> <property name="checkoutTimeout" value="${mysql.jdbc.checkoutTimeout}" /> <property name="idleConnectionTestPeriod" value="${mysql.jdbc.idleConnectionTestPeriod}" /> <property name="maxIdleTime" value="${mysql.jdbc.maxIdleTime}" /> <property name="maxStatements" value="${mysql.jdbc.maxStatements}" /> <property name="testConnectionOnCheckout" value="${mysql.jdbc.testConnectionOnCheckout}" /> </bean> <bean id="dataSourceOracle" class="com.mchange.v2.c3p0.ComboPooledDataSource" destroy-method="close"> <property name="driverClass" value="${oracle.jdbc.driverClass}" /> <property name="jdbcUrl" value="${oracle.jdbc.url}" /> <property name="user" value="${oracle.jdbc.user}" /> <property name="password" value="${oracle.jdbc.password}" /> <property name="initialPoolSize" value="${oracle.jdbc.initialPoolSize}" /> <property name="minPoolSize" value="${oracle.jdbc.minPoolSize}" /> <property name="maxPoolSize" value="${oracle.jdbc.maxPoolSize}" /> <property name="checkoutTimeout" value="${oracle.jdbc.checkoutTimeout}" /> <property name="idleConnectionTestPeriod" value="${oracle.jdbc.idleConnectionTestPeriod}" /> <property name="maxIdleTime" value="${oracle.jdbc.maxIdleTime}" /> <property name="maxStatements" value="${oracle.jdbc.maxStatements}" /> <property name="testConnectionOnCheckout" value="${oracle.jdbc.testConnectionOnCheckout}" /> </bean> <bean id="dataSource" class="com.core.DynamicDataSource"> <property name="targetDataSources"> <map key-type="java.lang.String"> <entry key="dataSourceMySql" value-ref="dataSourceMySql" /> <entry key="dataSourceOracle" value-ref="dataSourceOracle" /> </map> </property> <property name="defaultTargetDataSource" ref="dataSourceMySql" /> </bean> <bean id="sessionFactory" class="org.springframework.orm.hibernate4.LocalSessionFactoryBean"> <property name="dataSource" ref="dataSource" /> <property name="configLocation" value="classpath:com/resources/hibernate.cfg.xml" /> <property name="packagesToScan"> <list> <value>com.pojo.po</value> </list> </property> </bean> <bean id="transactionManager" class="org.springframework.orm.hibernate4.HibernateTransactionManager"> <property name="sessionFactory" ref="sessionFactory" /> </bean> <aop:config> <aop:pointcut id="serviceMethods" expression="execution(* com.service..*.*(..))" /> <aop:advisor advice-ref="txadvice" pointcut-ref="serviceMethods" /> </aop:config> <tx:advice id="txadvice" transaction-manager="transactionManager"> <tx:attributes> <tx:method name="add*" propagation="REQUIRED" /> <tx:method name="save*" 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="find*" read-only="true" propagation="SUPPORTS" /> <tx:method name="*" read-only="true" /> </tx:attributes> </tx:advice> <bean id="dataSourceInterceptor" class="com.core.DataSourceInterceptor" /> <aop:config> <aop:aspect id="dataSourceAspect" ref="dataSourceInterceptor"> <aop:pointcut id="dsMysql" expression="execution(* com.controller.mysql.*.*(..))" /> <aop:pointcut id="dsOracle" expression="execution(* com.controller.oracle.*.*(..))" /> <aop:before method="setdataSourceMysql" pointcut-ref="dsMysql"/> <aop:before method="setdataSourceOracle" pointcut-ref="dsOracle"/> </aop:aspect> </aop:config> </beans>
最下方即为双数据源切换，这个数据源切换没有问题，我碰到的为一个文件夹下的需要切换到需要的数据源，其他的全部为另外一个，我在想上面配置中defaultTargetDataSource，是不是就是在不切换的时候为默认的于是，我就把切换地方改成
<aop:config> <aop:aspect id="dataSourceAspect" ref="dataSourceInterceptor"> <aop:pointcut id="dsOracle" expression="execution(* com.controller.oracle.*.*(..))" /> <aop:before method="setdataSourceOracle" pointcut-ref="dsOracle"/> </aop:aspect> </aop:config>
这样，会不会是需要oracle数据源的时候就切换oracle，调用其他的就默认到了mysql那个库呢，结果运行的时候发现没有，可能是其他原因没有找到吧，于是我就在
expression="execution(这个表达式上面解决问题，比如除了上面表达式的文件下其他的都切换，类似这样
<aop:config> <aop:aspect id="dataSourceAspect" ref="dataSourceInterceptor"> <aop:pointcut id="dsMysql" expression="not execution(* com.controller.oracle.*.*(..))" /> <aop:pointcut id="dsOracle" expression="execution(* com.controller.oracle.*.*(..))" /> <aop:before method="setdataSourceMysql" pointcut-ref="dsMysql"/> <aop:before method="setdataSourceOracle" pointcut-ref="dsOracle"/> </aop:aspect> </aop:config>
结果网上搜了一大堆，什么！ nor not，都用了，但是仍然不好使，当然我觉得思路肯定是对的，至于原因还不知道。。于是换个方式，在com.core.DataSourceInterceptor中添加remove数据源，让用完数据源就remove掉，那样你总能用上defaultTargetDataSource吧，，然后果断好使了，当然写这个就是给大家提供思路，或许有其他解决方法呢。好吧上代码先，先看提供的两个切换类，配置中用到的com.core.DataSourceInterceptor
package com.core; import org.aspectj.lang.JoinPoint; public class DataSourceInterceptor { public void setdataSourceMysql(JoinPoint jp) { DatabaseContextHolder.setCustomerType("dataSourceMySql"); } public void setdataSourceOracle(JoinPoint jp) { DatabaseContextHolder.setCustomerType("dataSourceOracle"); } }
该类所调用的类 DatabaseContextHolder
package com.core; public class DatabaseContextHolder { private static final ThreadLocal<String> contextHolder = new ThreadLocal<String>(); public static void setCustomerType(String customerType) { contextHolder.set(customerType); } public static String getCustomerType() { return contextHolder.get(); } public static void clearCustomerType() { contextHolder.remove(); } }
于是就把DataSourceInterceptor中加个方法调用DatabaseContextHolder的clearCustomerType方法
于是有
package com.core; import org.aspectj.lang.JoinPoint; public class DataSourceInterceptor { public void setdataSourceMysql(JoinPoint jp) { DatabaseContextHolder.setCustomerType("dataSourceMySql"); } public void setdataSourceOracle(JoinPoint jp) { DatabaseContextHolder.setCustomerType("dataSourceOracle"); } public void removedataSource(JoinPoint jp){ DatabaseContextHolder.clearCustomerType(); } }
然后xml配置改成
<aop:config> <aop:aspect id="dataSourceAspect" ref="dataSourceInterceptor"> <aop:pointcut id="dsOracle" expression="execution(* com.controller.oracle.*.*(..))" /> <aop:before method="setdataSourceOracle" pointcut-ref="dsOracle"/> <aop:before method="removedataSource" pointcut-ref="dsOracle"/> </aop:aspect> </aop:config>
于是就大功告成了，当然，可能感觉比较粗糙，我也只是拾人牙慧而已。但若能给人提供下思路也是极好的。。
