ssm 动态切换数据源

1，添加数据库配置

jdbc.driver=com.microsoft.sqlserver.jdbc.SQLServerDriver
#jdbc.url=jdbc:sqlserver://192.168.1.73:1433; DatabaseName=HerPeisYCYTTJZX
#jdbc.username=sa
#jdbc.password=dky19921022
jdbc.url=jdbc:sqlserver://101.201.209.98:1433; DatabaseName=HerPeisGYFY
jdbc.username=sa
jdbc.password=BJBR_20170101

jdbc2.url=jdbc:sqlserver://101.201.209.98:1433; DatabaseName=HerpeisMYZXYY
jdbc2.username=sa
jdbc2.password=BJBR_20170101

2，添加数据库连接池及动态选择

    <!-- 数据库连接池 -->
    <!-- 加载配置文件 -->
    <context:property-placeholder location="classpath:resource/db.properties" />
    <!-- 数据库连接池 -->
    <bean id="dataSource1" class="com.alibaba.druid.pool.DruidDataSource"
        destroy-method="close">
        <property name="url" value="${jdbc.url}" />
        <property name="username" value="${jdbc.username}" />
        <property name="password" value="${jdbc.password}" />
        <property name="driverClassName" value="${jdbc.driver}" />
        <property name="maxActive" value="10" />
        <property name="minIdle" value="5" />
    </bean>

        <!-- 数据库连接池 -->
    <bean id="dataSource2" class="com.alibaba.druid.pool.DruidDataSource"
        destroy-method="close">
        <property name="url" value="${jdbc2.url}" />
        <property name="username" value="${jdbc2.username}" />
        <property name="password" value="${jdbc2.password}" />
        <property name="driverClassName" value="${jdbc.driver}" />
        <property name="maxActive" value="10" />
        <property name="minIdle" value="5" />
    </bean>
     -->
<bean id="dynamicDataSource" class="util.DynamicDataSource">
    <property name="targetDataSources">
        <map key-type="java.lang.String">
            <!-- 指定lookupKey和与之对应的数据源 -->
            <entry key="dataSource1" value-ref="dataSource1"></entry>
            <entry key="dataSource2" value-ref="dataSource2"></entry>
        </map>
    </property>
    <!-- 这里可以指定默认的数据源 -->
    <property name="defaultTargetDataSource" ref="dataSource1" />
</bean>

    <!-- 配置sqlsessionFactory -->
    <bean id="sqlSessionFactory" class="org.mybatis.spring.SqlSessionFactoryBean" >
        <property name="configLocation" value="classpath:resource/SqlMapConfig.xml"></property>
        <property name="dataSource" ref="dynamicDataSource"></property>
    </bean>

3，动态选择数据库的类DynamicDataSource及DynamicDataSourceHolder

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

public class DynamicDataSource extends AbstractRoutingDataSource {

    /**
     *  该方法返回需要使用的DataSource的key值，
     *  然后根据这个key从resolvedDataSources这个map里取出对应的DataSource，
     *  如果找不到，则用默认的resolvedDefaultDataSource。
     */
    @Override
    protected Object determineCurrentLookupKey() {
        // 从自定义的位置获取数据源标识
        return DynamicDataSourceHolder.getDataSource();
    }

}

public class DynamicDataSourceHolder {
    /**
     * 注意：数据源标识保存在线程变量中，避免多线程操作数据源时互相干扰
     */
    private static final ThreadLocal<String> THREAD_DATA_SOURCE = new ThreadLocal<String>();

    public static String getDataSource() {
        return THREAD_DATA_SOURCE.get();
    }

    public static void setDataSource(String dataSource) {
        THREAD_DATA_SOURCE.set(dataSource);
    }

    public static void clearDataSource() {
        THREAD_DATA_SOURCE.remove();
    }

}

4，调用

    @RequestMapping("ce")
    public String ce(HttpServletRequest req, HttpServletResponse res) throws UnsupportedEncodingException{

        Integer countUser = userService.countUser();//查询的是dataSource1的
        System.out.println(countUser);
        DynamicDataSourceHolder.setDataSource("dataSource2");
         System.out.println(userService.countUser());//查询的是dataSource2的
        return "login";
    }