spring动态设置多数据源

需求： 项目开发用的sping jdbctemplate, 之前数据源只有一个，现在数据源需要根据需求来进行变更, 也就是说

a用户------>需要访问A数据库服务器

b用户------>需要访问B数据库服务器

查询了资料，发现Spring提供了一个抽象类AbstractRoutingDataSource，为我们很方便的解决了这个问题。

实现：

Spring配置文件applicationContext.xml（包含相关bean类的代码）

<?xml version="1.0" encoding="UTF-8"?><beans xmlns="http://www.springframework.org/schema/beans"    xmlns:context="http://www.springframework.org/schema/context"    xmlns:jaxws="http://cxf.apache.org/jaxws"    xmlns:jaxrs="http://cxf.apache.org/jaxrs"    xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"    xmlns:tx="http://www.springframework.org/schema/tx"    xsi:schemaLocation="http://www.springframework.org/schema/beans     http://www.springframework.org/schema/beans/spring-beans-3.0.xsd    http://www.springframework.org/schema/context    http://www.springframework.org/schema/context/spring-context-3.0.xsd    http://cxf.apache.org/jaxws     http://cxf.apache.org/schemas/jaxws.xsd    http://cxf.apache.org/jaxrs    http://cxf.apache.org/schemas/jaxrs.xsd          http://www.springframework.org/schema/tx     http://www.springframework.org/schema/tx/spring-tx.xsd     http://www.springframework.org/schema/aop     http://www.springframework.org/schema/aop/spring-aop.xsd"><!-- <bean id="propertyConfigurer" class="org.springframework.beans.factory.config.PropertyPlaceholderConfigurer">        <property name="locations">            <list>                                <value>/WEB-INF/jdbc_config.properties</value>            </list>        </property>    </bean>     -->         <!--  这是原来的写法    <bean id="dataSource" class="org.springframework.jdbc.datasource.DriverManagerDataSource">      <property name="driverClassName" value="${jdbc.driverClassName}"/>      <property name="url" value="${jdbc.url}"/>      <property name="username" value="${jdbc.username}"/>      <property name="password" value="${jdbc.password}"/>    </bean>-->            <bean id="serverA" class="org.springframework.jdbc.datasource.DriverManagerDataSource">      <property name="driverClassName"   value="com.mysql.jdbc.Driver"/>      <property name="url"   value="jdbc:mysql://localhost:3306/test2?useUnicode=true&amp;characterEncoding=utf8" />      <property name="username"  value="root"/>      <property name="password"  value="tiger"/>    </bean>        <bean id="serverB" class="org.springframework.jdbc.datasource.DriverManagerDataSource">      <property name="driverClassName"   value="com.mysql.jdbc.Driver"/>      <property name="url"   value="jdbc:mysql://112.112.11.132:3306/test?useUnicode=true&amp;characterEncoding=utf8"/>      <property name="username"   value="root" />      <property name="password"   value="tiger"/>    </bean>        <!-- 这里是重点 -->    <bean id="dataSource" class="com.rr.datasource.DynamicDataSource">    <property name="targetDataSources">        <map key-type="java.lang.String">            <entry key="server127" value-ref="serverA" />            <entry key="server112" value-ref="serverB" />        </map>    </property>    <property name="defaultTargetDataSource"  ref="serverA" /></bean>        <!--注入 spring jdbcTemplate -->   <bean id="jdbcTemplate" class="org.springframework.jdbc.core.JdbcTemplate">           <property name="dataSource" ref="dataSource"/>   </bean>        <!-- dao -->    <bean id="initDaoImpl"  class="com.rr.dao.impl.InitDao">        <property name="jdbcTemplate" ref="jdbcTemplate"></property>    </bean>        <!-- service -->    <bean id="grantForCompany" class="com.rr.service.GrantForCompany">        <property name="initDao" ref="initDaoImpl"></property>        <property name="jdbcTemplate" ref="jdbcTemplate"></property>    </bean>        <!-- 事务管理 -->   <bean id="transctionManager"        class="org.springframework.jdbc.datasource.DataSourceTransactionManager">        <property name="dataSource" ref="dataSource"></property>    </bean>    <tx:annotation-driven transaction-manager="transctionManager"/>         </beans>

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

import org.springframework.jdbc.datasource.lookup.AbstractRoutingDataSource;public class DynamicDataSource extends AbstractRoutingDataSource {    @Override    protected Object determineCurrentLookupKey()    {                return DatabaseContextHolder.getCustomerType();      }}

3. 写一个线程安全的ThreadLocal（这个ThreadLocal详细见下篇博客,我之前也没有接触过）

public class DatabaseContextHolder{    private static final ThreadLocal<String> contextHolder = new ThreadLocal<String>();    public static void setCustomerType(String customerType) {          contextHolder.set(customerType);      }        public static String getCustomerType() {          return contextHolder.get();      }        public static void clearCustomerType() {          contextHolder.remove();      }}

 

4.当需要切换数据源时，调用一行代码就可以了(也可以用aop自动切换,根据自己需求吧)

DbContextHolder.setDbType("server112"); //server112 就是配置文件中那个targetDataSources的key 
targetDataSources是一个map,可以看spring提供的源码.