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。

研究成果如下：

1、首先配置多个 datasource

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>  
    

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 contextHolder = new ThreadLocal();  
   

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

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);

搞定！