spring mvc+mybatis+多数据源切换

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

<?xml version="1.0" encoding="UTF-8"?>
<web-app xmlns="http://java.sun.com/xml/ns/javaee" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
    xsi:schemaLocation="http://java.sun.com/xml/ns/javaee http://java.sun.com/xml/ns/javaee/web-app_2_5.xsd"
    version="2.5">
    <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>
</web-app>

dispatcher.xml

<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" xmlns:p="http://www.springframework.org/schema/p"
    xmlns:tx="http://www.springframework.org/schema/tx" xmlns:jdbc="http://www.springframework.org/schema/jdbc"
    xmlns:util="http://www.springframework.org/schema/util" xmlns:mvc="http://www.springframework.org/schema/mvc"
    xsi:schemaLocation="
        http://www.springframework.org/schema/beans
        http://www.springframework.org/schema/beans/spring-beans.xsd
        http://www.springframework.org/schema/context
        http://www.springframework.org/schema/context/spring-context.xsd
        http://www.springframework.org/schema/util 
        http://www.springframework.org/schema/util/spring-util.xsd
        http://www.springframework.org/schema/tx  
        http://www.springframework.org/schema/tx/spring-tx.xsd
        http://www.springframework.org/schema/aop  
        http://www.springframework.org/schema/aop/spring-aop.xsd
        http://www.springframework.org/schema/jdbc  
           http://www.springframework.org/schema/jdbc/spring-jdbc.xsd
        http://www.springframework.org/schema/mvc 
        http://www.springframework.org/schema/mvc/spring-mvc.xsd ">
    <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>

</beans>

applicationContext.xml

<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" xmlns:p="http://www.springframework.org/schema/p"
    xmlns:tx="http://www.springframework.org/schema/tx" xmlns:jdbc="http://www.springframework.org/schema/jdbc"
    xmlns:util="http://www.springframework.org/schema/util" xmlns:mvc="http://www.springframework.org/schema/mvc"
    xsi:schemaLocation="
        http://www.springframework.org/schema/beans
        http://www.springframework.org/schema/beans/spring-beans.xsd
        http://www.springframework.org/schema/context
        http://www.springframework.org/schema/context/spring-context.xsd
        http://www.springframework.org/schema/util 
        http://www.springframework.org/schema/util/spring-util.xsd
        http://www.springframework.org/schema/tx  
        http://www.springframework.org/schema/tx/spring-tx.xsd
        http://www.springframework.org/schema/aop  
        http://www.springframework.org/schema/aop/spring-aop.xsd
        http://www.springframework.org/schema/jdbc  
           http://www.springframework.org/schema/jdbc/spring-jdbc.xsd
        http://www.springframework.org/schema/mvc 
        http://www.springframework.org/schema/mvc/spring-mvc.xsd ">
    <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>
</beans>

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;  
    }  
} 

本文转自：http://leoyy.iteye.com/blog/1624704