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Java之SpringMVC+MyBitis+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
 
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<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
 
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<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
 
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<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
 
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/** 
 * 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
 
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/** 
 * 
 * @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
 
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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
 
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@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;  
    }  
}