Spring @ transactional，如何配置数据库的两个不同节点

<bean id="dataSource1" class="org.springframework.jdbc.datasource.DriverManagerDataSource">
    <property name="driverClassName" value="com.mysql.jdbc.Driver" />
    <property name="url" value="jdbc:mysql://localhost:3306/db1" />
    <property name="username" value="username1" />
    <property name="password" value="password1" />
</bean>

<bean id="dataSource2" class="org.springframework.jdbc.datasource.DriverManagerDataSource">
    <property name="driverClassName" value="com.mysql.jdbc.Driver" />
    <property name="url" value="jdbc:mysql://localhost:3306/db2" />
    <property name="username" value="username2" />
    <property name="password" value="password2" />
</bean>

<bean id="transactionManager" class="org.springframework.jdbc.datasource.DataSourceTransactionManager">
    <property name="dataSource" ref="dataSource1" />
</bean>

<tx:advice id="txAdvice" transaction-manager="transactionManager">
    <tx:attributes>
        <tx:method name="*" />
    </tx:attributes>
</tx:advice>

<aop:config>
    <aop:advisor advice-ref="txAdvice" pointcut="execution(* com.example.*.*(..))" />
</aop:config>

@Transactional("transactionManager")
public void doSomething() {
    // 事务性操作
}