利用Spring的AbstractRoutingDataSource解决多数据源的问题

多数据源问题很常见，例如读写分离数据库配置。

原来的项目出现了新需求，局方要求新增某服务器用以提供某代码，涉及到多数据源的问题。

解决方法如下：

1、首先配置多个datasource

 1 <bean id="dataSource" class="org.apache.commons.dbcp.BasicDataSource">
 2      <property name="driverClassName" value="net.sourceforge.jtds.jdbc.Driver">
 3   </property>
 4   <property name="url" value="jdbc:jtds:sqlserver://10.82.81.51:1433;databaseName=standards">
 5   </property>
 6   <property name="username" value="youguess"></property>
 7   <property name="password" value="youguess"></property>
 8  </bean>
 9  <bean id="dataSource2" class="org.apache.commons.dbcp.BasicDataSource">
10      <property name="driverClassName" value="net.sourceforge.jtds.jdbc.Driver">
11   </property>
12   <property name="url" value="jdbc:jtds:sqlserver://10.82.81.52:1433;databaseName=standards">
13   </property>
14   <property name="username" value="youguess"></property>
15   <property name="password" value="youguess"></property>
16 </bean>

2、写一个DynamicDataSource类继承AbstractRoutingDataSource，并实现determineCurrentLookupKey方法

1 package com.standard.core.util;
2 import org.springframework.jdbc.datasource.lookup.AbstractRoutingDataSource;
3 public class DynamicDataSource extends AbstractRoutingDataSource {
4     @Override
5     protected Object determineCurrentLookupKey() {
6         return CustomerContextHolder.getCustomerType();
7     }
8 }

3、利用ThreadLocal解决线程安全问题

 1 package com.standard.core.util;
 2 public class CustomerContextHolder {
 3     public static final String DATA_SOURCE_A = "dataSource";
 4     public static final String DATA_SOURCE_B = "dataSource2";
 5     private static final ThreadLocal<String> contextHolder = new ThreadLocal<String>();
 6     public static void setCustomerType(String customerType) {
 7         contextHolder.set(customerType);
 8     }
 9     public static String getCustomerType() {
10         return contextHolder.get();
11     }
12     public static void clearCustomerType() {
13         contextHolder.remove();
14     }
15 }

4、数据源配置

 1 <bean id="dynamicDataSource" class="com.standard.core.util.DynamicDataSource" >
 2         <property name="targetDataSources">
 3             <map key-type="java.lang.String">
 4                 <entry value-ref="dataSource" key="dataSource"></entry>
 5                 <entry value-ref="dataSource2" key="dataSource2"></entry>
 6             </map>
 7         </property>
 8         <property name="defaultTargetDataSource" ref="dataSource" >
 9         </property>
10     </bean>

5、在DAOImpl中切换数据源

1 CustomerContextHolder.setCustomerType(CustomerContextHolder.DATA_SOURCE_B);