利用spring+ibatiS技術，在spring中配置多個數據源，並實現動態切換。

spring中xml文件中的配置：

<bean id="dataSource1"
  class="com.mchange.v2.c3p0.ComboPooledDataSource"> 
  <property name="driverClass"><value>oracle.jdbc.driver.OracleDriver</value></property>

  <property name="jdbcUrl"><value>jdbc:oracle:thin:@127.0.0.1:1521:ORACLE</value></property>
  <property name="user"><value>htctposp</value></property> 
  <property name="password"><value>htctposp</value></property> 
  <property name="minPoolSize"><value>1</value></property> 
  <property name="maxPoolSize"><value>5</value></property> 
  <property name="maxIdleTime"><value>1800</value></property> 
  </bean>
<bean id="dataSource2" class="org.springframework.jdbc.datasource.DriverManagerDataSource">
        <property name="driverClassName" value="com.mysql.jdbc.Driver"></property>
        <property name="url" value="jdbc:mysql://localhost:3306/mysql?characterEncoding=UTF8"></property>
        <property name="username" value="root"></property>
        <property name="password" value="1111"></property>
    </bean> 
   
<bean id="dataSource" class="com.huateng.util.DynamicDataSource">      
         <property name="targetDataSources">   
          <map key-type="java.lang.String">      
                <entry key="dataSource1" value-ref="dataSource1"/>   
                 <entry key="dataSource2" value-ref="dataSource2"/>   
             </map>     
          </property>      
          <property name="defaultTargetDataSource" ref="dataSource1"/>      
</bean>

    <!-- SqlMap setup for iBATIS Database Layer -->   
    <bean id="sqlMapClient" class="org.springframework.orm.ibatis.SqlMapClientFactoryBean">   
        <property name="dataSource" ref="dataSource"/>   
        <property name="configLocation" value="classpath:com/xxx/xxx/dao/sqlmap/sql-map-config.xml"/>  
    </bean>

寫兩個工具類DbContextHolder和DynamicDataSource，以下：

public class DynamicDataSource extends AbstractRoutingDataSource{

 static Logger log=Logger.getLogger("DynamicDataSource");
 /* (non-Javadoc)
  * @see org.springframework.jdbc.datasource.lookup.AbstractRoutingDataSource#determineCurrentLookupKey()
  */
 protected Object determineCurrentLookupKey() {
      return DbContextHolder.getDbType();
 }

}

public class DbContextHolder {
 private static final ThreadLocal contextHolder = new ThreadLocal();
 
 public static void setDbType(String dbType){
  contextHolder.set(dbType);
 }
 
 public static String getDbType(){
  return (String)contextHolder.get();
 }
 
 public static void clearDbType(){
  contextHolder.remove();
 }

}

通常在調用service層以前就要切換數據庫（通常要在action中或者說在事務外圍更準確），切換數據庫的代碼：
 

 DbContextHolder.setDbType("dataSource2");

參考：

https://blog.csdn.net/f_d_q/article/details/6927546 

http://exceptioneye.iteye.com/blog/1698090