Spring多数据源的动态切换

目前很多项目中只能配置单个数据源，那么如果有多个数据源肿么办？Spring提供了一个抽象类AbstractRoutingDataSource，为我们很方便的解决了这个问题。
1.写一个DynamicDataSource类继承AbstractRoutingDataSource，并实现determineCurrentLookupKey方法

public class DynamicDataSource extends AbstractRoutingDataSource{
 private final static Logger  logger  = LoggerFactory.getLogger("DynamicDataSource");   
 
    @Override  
    protected Object determineCurrentLookupKey() {   
        return DbContextHolder.getDbType();   
    }   
}

2.写一个线程安全的ThreadLocal

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();   
    }   
}

3.dataSource的配置
<?xml version="1.0" encoding="UTF-8"?>
<beans xmlns="http://www./schema/beans" xmlns:xsi="http://www./2001/XMLSchema-instance"
xmlns:p="http://www./schema/p" xmlns:context="http://www./schema/context"
xsi:schemaLocation="http://www./schema/beans http://www./schema/beans/spring-beans-2.5.xsd
http://www./schema/context http://www./schema/context/spring-context-2.5.xsd"
default-autowire="byName">

<bean id="aTestDataSource" class="org.springframework.jdbc.datasource.DriverManagerDataSource">
<property name="driverClassName" value="${a.jdbc.driverClassName}" />
<property name="url" value="${a.jdbc.url}" />
<property name="username" value="${a.jdbc.username}" />
<property name="password" value="${a.jdbc.password}" />
</bean>

<bean id="bTestDataSource" class="org.springframework.jdbc.datasource.DriverManagerDataSource">
<property name="driverClassName" value="${b.jdbc.driverClassName}" />
<property name="url" value="${gott.jdbc.url}" />
<property name="username" value="${b.jdbc.username}" />
<property name="password" value="${b.jdbc.password}" />
</bean>

<bean id="dataSource" class="***.DynamicDataSource">
<property name="targetDataSources">
<map key-type="java.lang.String">
<entry key="aTestDataSource" value-ref="aTestDataSource" />
<entry key="bTestDataSource" value-ref="bTestDataSource" />
</map>
</property>
<property name="aTestDataSource" ref="aTestDataSource" />
</bean>
</beans>

4.当需要切换数据源时，只要调用一行代码就可以了

DbContextHolder.setDbType("aTestDataSource");

当然有兴趣的朋友也可以用aop去自动切换数据源