spring mvc+mybatis+多数据源切换 选取oracle,mysql作为例子切换数据源。oracle为默认数据源，在测试的action中，进行mysql和oracle的动态切换。

web.xml

<context-param>

<param-name>webAppRootKey</param-name>

<param-value>trac</param-value>

</context-param>

<!-- Spring的log4j监听器 -->

<listener>

<listener-class>org.springframework.web.util.Log4jConfigListener</listener-class>

</listener>

<!-- 字符集 过滤器 -->

<filter>

<filter-name>CharacterEncodingFilter</filter-name>

<filter-class>org.springframework.web.filter.CharacterEncodingFilter</filter-class>

<init-param>

<param-name>encoding</param-name>

<param-value>utf8</param-value>

</init-param>

<init-param>

<param-name>forceEncoding</param-name>

<param-value>true</param-value>

</init-param>

</filter>

<filter-mapping>

<filter-name>CharacterEncodingFilter</filter-name>

<url-pattern>/*</url-pattern>

</filter-mapping>

<!-- Spring view分发器 -->

<servlet>

<servlet-name>dispatcher</servlet-name>

<servlet-class>org.springframework.web.servlet.DispatcherServlet</servlet-class>

<init-param>

<param-name>contextConfigLocation</param-name>

<param-value>/WEB-INF/dispatcher.xml</param-value>

</init-param>

<load-on-startup>1</load-on-startup>

</servlet>

<servlet-mapping>

<servlet-name>dispatcher</servlet-name>

<url-pattern>*.action</url-pattern>

</servlet-mapping>

<listener>

<listener-class>org.springframework.web.context.ContextLoaderListener</listener-class>

</listener>

dispatcher.xml

<mvc:annotation-driven />

<context:component-scan base-package="com.trac" />

<bean id="multipartResolver" class="org.springframework.web.multipart.commons.CommonsMultipartResolver" />

<!-- freemarker config -->

<bean id="freemarkerConfig" class="org.springframework.web.servlet.view.freemarker.FreeMarkerConfigurer">

<property name="templateLoaderPath" value="/WEB-INF/freemarker/" />

<property name="freemarkerVariables">

<map>

<entry key="xml_escape" value-ref="fmXmlEscape" />

</map>

</property>

<property name="freemarkerSettings">

<props>

<prop key="defaultEncoding">UTF-8</prop>

</props>

</property>

</bean>

<bean id="fmXmlEscape" class="freemarker.template.utility.XmlEscape" />

<!-- View resolvers can also be configured with ResourceBundles or XML files. 

If you need different view resolving based on Locale, you have to use the 

resource bundle resolver. -->

<bean id="viewResolver" class="org.springframework.web.servlet.view.freemarker.FreeMarkerViewResolver">

<property name="exposeRequestAttributes" value="true" />

<property name="exposeSessionAttributes" value="true" />

<property name="exposeSpringMacroHelpers" value="true" />

<property name="contentType" value="text/html;charset=UTF-8" />

<property name="cache" value="true" />

<property name="prefix" value="" />

<property name="suffix" value=".ftl" />

</bean>

applicationContext.xml

<bean id="parentDataSource" class="org.springframework.jdbc.datasource.DriverManagerDataSource">

</bean>

<bean id="mySqlDataSource" parent="parentDataSource">

<property name="driverClassName" value="com.mysql.jdbc.Driver"></property>

<property name="url" value="jdbc:mysql://localhost:3306/test"></property>

<property name="username" value="root"></property>

<property name="password" value="root"></property>

</bean>

<bean id="oracleDataSource" parent="parentDataSource">

<property name="driverClassName" value="oracle.jdbc.driver.OracleDriver"></property>

<property name="url" value="jdbc:oracle:thin:@10.16.17.40:1531:addb"></property>

<property name="username" value="trac"></property>

<property name="password" value="trac"></property>

</bean>

<bean id="dataSource" class="com.trac.dao.datasource.DataSources">

<property name="targetDataSources">

<map key-type="java.lang.String">

<entry value-ref="mySqlDataSource" key="MYSQL"></entry>

<entry value-ref="oracleDataSource" key="ORACLE"></entry>

</map>

</property>

<property name="defaultTargetDataSource" ref="oracleDataSource"></property>

</bean>

<bean id="transactionManager" class="org.springframework.jdbc.datasource.DataSourceTransactionManager">

<property name="dataSource" ref="dataSource" />

</bean>

<!-- 创建SqlSessionFactory，同时指定数据源和mapper -->

<bean id="sqlSessionFactory" class="org.mybatis.spring.SqlSessionFactoryBean">

<property name="dataSource" ref="dataSource" />

<property name="mapperLocations" value="classpath*:com/trac/ibatis/dbcp/*.xml" />

</bean>

<bean id="sqlSession" class="org.mybatis.spring.SqlSessionTemplate">

<constructor-arg index="0" ref="sqlSessionFactory" />

</bean>

<bean class="org.mybatis.spring.mapper.MapperScannerConfigurer">

<property name="basePackage" value="com.trac.dao" />

</bean>

配置 parentDataSource 的父bean.再配置多个数据源继承这个父bean,对driverClass,url,username,password,等数据源连接参数进行各自的重写。例如 mySqlDataSource ，在 DataSources bean中注入所有要切换的数据源，并且设置默认的数据源。

DataSourceInstances.java

/**

 * 定义数据源的标识, 和applicationContext.xml中 DataSources 的 targetDataSources 的key对应

 * @author liuyazhuang

 */

public class DataSourceInstances{

public static final String MYSQL="MYSQL";

public static final String ORACLE="ORACLE";

}

DataSourceSwitch.java

/**

 *

 * @author liuyazhuang

 */

public class DataSourceSwitch{

private static final ThreadLocal contextHolder=new ThreadLocal();

public static void setDataSourceType(String dataSourceType){

contextHolder.set(dataSourceType);

}

public static String getDataSourceType(){

return (String) contextHolder.get();

}

public static void clearDataSourceType(){

contextHolder.remove();

}

}

DataSources.java

import org.springframework.jdbc.datasource.lookup.AbstractRoutingDataSource;

/**

 *配置于applicationContext 中，线程局部变量ThreadLocal contextHolder 保存当前需要的数据源类型，当 DataSourceSwitch. setDataSourceType(DataSourceInstances.XXX) 保存当前需要的数据源类型的时候，DataSources 会从当前线程中查找线程变量的数据源类型，从而决定使用何种数据源

 * @author liuyazhuang

 */

public class DataSources extends AbstractRoutingDataSource{

@Override

protected Object determineCurrentLookupKey() {

return DataSourceSwitch.getDataSourceType();

}

}

TestAction.java

@Controller

@SuppressWarnings("unused")

public class TestAction {

@Autowired

TestMapper testMapper;

   @RequestMapping("/test.action")

public ModelAndView test(

HttpServletRequest request,

HttpServletResponse resp){

ModelAndView model = new ModelAndView("test");

model.addObject("test1", "这是一个测试,获取默认数据连接MYSQL:"+testMapper.test());

DataSourceSwitch.setDataSourceType(DataSourceInstances.ORACLE);

model.addObject("test2", "这是一个测试,获取数据连接ORACLE:"+testMapper.test());

DataSourceSwitch.setDataSourceType(DataSourceInstances.MYSQL);

model.addObject("test3", "这是一个测试,获取数据连接MYSQL:"+testMapper.test());

return model;

}

}

---------------------