spring+mybatis+多数据源切换

gmdzxx

　　转载  http://leoannto.iyunv.com/blog/1624704
　　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.whjh.cust.datesource.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> <!--设置默认的数据源-->
</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="configLocation" value="classpath:sqlMapConfig.xml" />
<property name="mapperLocations" value="classpath*:com/**/model/mapper/*.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.whjh.cust.model.mapper" /><!--mapper.xml的包结构-->
</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 

public class DataSourceInstances{  
public static final String MYSQL="MYSQL";  
public static final String ORACLE="ORACLE";  
}     
定义数据源的标识, 和applicationContext.xml中 DataSources 的 targetDataSources 的key对应  
　　DataSourceSwitch.java 

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;  
public class DataSources extends AbstractRoutingDataSource{  
@Override  
protected Object determineCurrentLookupKey() {  
return DataSourceSwitch.getDataSourceType();  
}  
}  
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  
　　 
　　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;  
}  
}