Java之——SpringMVC+MyBitis+多数据源切换

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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;
}
}