spring 多个数据库之间切换

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

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>

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代码中手动切换数据源

1. CustomerContextHolder.setCustomerType(CustomerContextHolder.DATA_SOURCE_B);   
6、或者用AOP动态切换数据源
package datasource;
import org.aspectj.lang.JoinPoint;

import org.aspectj.lang.annotation.Aspect;

import org.aspectj.lang.annotation.Before;

import org.aspectj.lang.annotation.Pointcut;@Aspect

public class DynamicDataSourceAspect {

 @Pointcut("execution (public service.impl..*.*(..))")

 public void serviceExecution(){}

 

 @Before("serviceExecution()")

 public void setDynamicDataSource(JoinPoint jp) {

  for(Object o : jp.getArgs()) {

   //处理具体的逻辑 ，根据具体的境况CustomerContextHolder.setCustomerType()选取DataSource

  }

 }

}

搞定！