Spring 多数据源动态切换

 为了实现多数据源的动态切换，降低代码耦合度，特地使用了AOP

第一步就要先配置多个数据源支持，下面的这个是我配置的两个数据源和多数据源支持。我这个是没有用mybatis和hibernate的，直接用的jdbcTemplate.

<bean id="dataSourceDemo" class="org.apache.commons.dbcp.BasicDataSource" destroy-method="close">		<PRoperty name="driverClassName"> <value>${driverClassName}</value></property>		<property name="url"><value>${url}</value></property>		<property name="username"><value>${username}</value></property>		<property name="passWord"><value>${password}</value></property>		<property name="maxActive"><value>150</value></property>		<property name="maxIdle"> <value>20</value></property>        <property name="removeAbandoned"> <value>true</value></property>		<property name="removeAbandonedTimeout"><value>180</value></property>		<property name="maxWait"><value>10000</value></property>	</bean>           <bean id="dataSourceTarget"  class="org.apache.commons.dbcp.BasicDataSource" destroy-method="close">		<property name="driverClassName"> <value>${driverClassName}</value></property>		<property name="url"><value>${urlHebi}</value></property>		<property name="username"><value>${usernameHebi}</value></property>		<property name="password"><value>${passwordHebi}</value></property>		<property name="maxActive"><value>150</value></property>		<property name="maxIdle"> <value>20</value></property>        <property name="removeAbandoned"> <value>true</value></property>		<property name="removeAbandonedTimeout"><value>180</value></property>		<property name="maxWait"><value>10000</value></property>	</bean>		 				<bean id="dynamicDataSource" class="com.simple.dispatch.datasource.DynamicDataSource" >      <!-- 通过key-value的形式来关联数据源 -->  	    <property name="targetDataSources">  	        <map>  	            <entry value-ref="dataSourceLaiya" key="dataSourceLaiyang"></entry>  	            <entry value-ref="dataSourceChangyuan" key="dataSourceChangyuan"></entry>  	           	             	        </map>  	    </property>  	    <property name="defaultTargetDataSource" ref="dataSourceLaiyang" />      </bean>   		<!-- jdbc模板 -->	<bean id="jdbcTemplate" class="org.springframework.jdbc.core.JdbcTemplate">  	    <property name="dataSource">  	        <ref bean="dynamicDataSource" />  	    </property>      </bean>    				<bean class="org.springframework.jdbc.datasource.DataSourceTransactionManager" id="transactionManager">		<property name="dataSource" ref="dynamicDataSource" />	</bean> 
第二步自定义一个注解类
@Target({ElementType.METHOD, ElementType.TYPE})  @Retention(RetentionPolicy.RUNTIME)  @Documented   public @interface DataSource {		String name() default "dataSource";  }第三步配置动态切换类库
public class DynamicDataSource extends AbstractRoutingDataSource{	@Override	protected Object determineCurrentLookupKey() {		// TODO Auto-generated method stub				return CustomerContextHolder.getDBType();	}}
public class CustomerContextHolder {	                              private static final ThreadLocal<String> contextHolder = new ThreadLocal<String>();            public static void setDBType(String dbType) {          contextHolder.set(dbType);      }            public static String getDBType() {          return contextHolder.get();      }            public static void clearDBType() {          contextHolder.remove();      }          }第四步配置AOP切面，完成切面通知信息
public class DataSourceaspect  {		public void pointcut(){			};  		public void before(JoinPoint point)      {  				MethodSignature methodSignature = (MethodSignature) point.getSignature();        Object target = point.getTarget();          String method = methodSignature.getName();          try {          	Method m = methodSignature.getMethod();                        if (m != null &&m.isAnnotationPresent(DataSource.class)) {                  DataSource data = m.getAnnotation(DataSource.class);                  CustomerContextHolder.setDBType(data.name());              }                        } catch (Exception e) {              e.printStackTrace();          }      }  }
第五步 在spring配置文件中，加入切面影响的切入点
<bean id="dataSourceAspect" class="com.simple.dispatch.datasource.DataSourceAspect" />   <aop:config>  	     <aop:aspect id="c" ref="dataSourceAspect">  	        <aop:pointcut id="allSimpleServiceMethodPO" expression="execution(* com.simple.dispatch.*.service.impl.*.*(..))"/>  	        <aop:before pointcut-ref="allSimpleServiceMethodPO" method="before"/>  	    </aop:aspect>     </aop:config>
经过以上步骤就完成了多数据源的动态切换。以下为调用实例：
@DataSource(name="dataSourceDemo")	public List getDemoList() throws Exception{                      return null;}