spring多数据源配置

项目中我们经常会遇到多数据源的问题，尤其是数据同步或定时任务等项目更是如此。多数据源让人最头痛的，不是配置多个数据源，而是如何能灵活动态的切换数据源。例如在一个spring和hibernate的框架的项目中，我们在spring配置中往往是配置一个dataSource来连接数据库，然后绑定给sessionFactory，在dao层代码中再指定sessionFactory来进行数据库操作。

正如上图所示，每一块都是指定绑死的，如果是多个数据源，也只能是下图中那种方式。

可看出在Dao层代码中写死了两个SessionFactory，这样日后如果再多一个数据源，还要改代码添加一个SessionFactory，显然这并不符合开闭原则。

那么正确的做法应该是

代码如下：

1. applicationContext.xml

<?xml version="1.0" encoding="UTF-8"?><beans xmlns="http://www.springframework.org/schema/beans"xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xmlns:aop="http://www.springframework.org/schema/aop"xmlns:cache="http://www.springframework.org/schema/cache"xmlns:context="http://www.springframework.org/schema/context"xmlns:jdbc="http://www.springframework.org/schema/jdbc" xmlns:jee="http://www.springframework.org/schema/jee"xmlns:jms="http://www.springframework.org/schema/jms" xmlns:lang="http://www.springframework.org/schema/lang"xmlns:mvc="http://www.springframework.org/schema/mvc" xmlns:oxm="http://www.springframework.org/schema/oxm"xmlns:p="http://www.springframework.org/schema/p" xmlns:task="http://www.springframework.org/schema/task"xmlns:tx="http://www.springframework.org/schema/tx" xmlns:util="http://www.springframework.org/schema/util"xsi:schemaLocation="http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans.xsd  http://www.springframework.org/schema/aop http://www.springframework.org/schema/aop/spring-aop-3.1.xsd     http://www.springframework.org/schema/cache http://www.springframework.org/schema/cache/spring-cache-3.1.xsd      http://www.springframework.org/schema/context http://www.springframework.org/schema/context/spring-context-3.1.xsd      http://www.springframework.org/schema/jdbc http://www.springframework.org/schema/jdbc/spring-jdbc-3.1.xsd      http://www.springframework.org/schema/jee http://www.springframework.org/schema/jee/spring-jee-3.1.xsd      http://www.springframework.org/schema/jms http://www.springframework.org/schema/jms/spring-jms-3.1.xsd    http://www.springframework.org/schema/lang http://www.springframework.org/schema/lang/spring-lang-3.1.xsd     http://www.springframework.org/schema/mvc http://www.springframework.org/schema/mvc/spring-mvc-3.1.xsd    http://www.springframework.org/schema/oxm http://www.springframework.org/schema/oxm/spring-oxm-3.1.xsd   http://www.springframework.org/schema/task http://www.springframework.org/schema/task/spring-task-3.1.xsd      http://www.springframework.org/schema/tx http://www.springframework.org/schema/tx/spring-tx-3.1.xsd      http://www.springframework.org/schema/util http://www.springframework.org/schema/util/spring-util-3.1.xsd"><context:annotation-config /><context:component-scan base-package="com"></context:component-scan><bean class="org.springframework.beans.factory.config.PropertyPlaceholderConfigurer"><property name="locations"><list><value>classpath:com/resource/config.properties</value></list></property></bean><bean id="dataSourceOne" class="com.mchange.v2.c3p0.ComboPooledDataSource"destroy-method="close"><property name="driverClass" value="${dbOne.jdbc.driverClass}" /><property name="jdbcUrl" value="${dbOne.jdbc.url}" /><property name="user" value="${dbOne.jdbc.user}" /><property name="password" value="${dbOne.jdbc.password}" /><property name="initialPoolSize" value="${dbOne.jdbc.initialPoolSize}" /><property name="minPoolSize" value="${dbOne.jdbc.minPoolSize}" /><property name="maxPoolSize" value="${dbOne.jdbc.maxPoolSize}" /></bean><bean id="dataSourceTwo" class="com.mchange.v2.c3p0.ComboPooledDataSource"destroy-method="close"><property name="driverClass" value="${dbTwo.jdbc.driverClass}" /><property name="jdbcUrl" value="${dbTwo.jdbc.url}" /><property name="user" value="${dbTwo.jdbc.user}" /><property name="password" value="${dbTwo.jdbc.password}" /><property name="initialPoolSize" value="${dbTwo.jdbc.initialPoolSize}" /><property name="minPoolSize" value="${dbTwo.jdbc.minPoolSize}" /><property name="maxPoolSize" value="${dbTwo.jdbc.maxPoolSize}" /></bean><bean id="dynamicDataSource" class="com.core.DynamicDataSource"><property name="targetDataSources"><map key-type="java.lang.String"><entry value-ref="dataSourceOne" key="dataSourceOne"></entry><entry value-ref="dataSourceTwo" key="dataSourceTwo"></entry></map></property><property name="defaultTargetDataSource" ref="dataSourceOne"></property></bean><bean id="sessionFactory" class="org.springframework.orm.hibernate4.LocalSessionFactoryBean"><property name="dataSource" ref="dynamicDataSource" /><property name="hibernateProperties"><props><prop key="hibernate.dialect">org.hibernate.dialect.MySQLDialect</prop><prop key="hibernate.current_session_context_class">org.springframework.orm.hibernate4.SpringSessionContext</prop><prop key="hibernate.show_sql">false</prop><prop key="hibernate.format_sql">true</prop><prop key="hbm2ddl.auto">create</prop></props></property><property name="packagesToScan"><list><value>com.po</value></list></property></bean><pre name="code" class="html" style="font-size: 14.4444446563721px; line-height: 26px; text-indent: 28px;">    <aop:config><aop:aspect id="dataSourceAspect" ref="dataSourceInterceptor"><aop:pointcut id="daoOne" expression="execution(* com.dao.one.*.*(..))" /><aop:pointcut id="daoTwo" expression="execution(* com.dao.two.*.*(..))" /><aop:before pointcut-ref="daoOne" method="setdataSourceOne" /><aop:before pointcut-ref="daoTwo" method="setdataSourceTwo" /></aop:aspect></aop:config>

<bean id="transactionManager" class="org.springframework.orm.hibernate4.HibernateTransactionManager"><property name="sessionFactory" ref="sessionFactory" /></bean><aop:config><aop:pointcut id="transactionPointCut" expression="execution(* com.dao..*.*(..))" /><aop:advisor advice-ref="txAdvice" pointcut-ref="transactionPointCut" /></aop:config><tx:advice id="txAdvice" transaction-manager="transactionManager"><tx:attributes><tx:method name="add*" propagation="REQUIRED" /><tx:method name="save*" propagation="REQUIRED" /><tx:method name="update*" propagation="REQUIRED" /><tx:method name="delete*" propagation="REQUIRED" /><tx:method name="*" read-only="true" /></tx:attributes></tx:advice></beans>

DynamicDataSource.java

package com.core;import org.springframework.jdbc.datasource.lookup.AbstractRoutingDataSource;public class DynamicDataSource extends AbstractRoutingDataSource{@Overrideprotected Object determineCurrentLookupKey() {return DatabaseContextHolder.getCustomerType(); }}

DatabaseContextHolder.java

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();}}

DataSourceInterceptor.java

package com.core;import org.aspectj.lang.JoinPoint;import org.springframework.stereotype.Component;@Componentpublic class DataSourceInterceptor {public void setdataSourceOne(JoinPoint jp) {DatabaseContextHolder.setCustomerType("dataSourceOne");}public void setdataSourceTwo(JoinPoint jp) {DatabaseContextHolder.setCustomerType("dataSourceTwo");}}

po实体类

package com.po;import javax.persistence.Column;import javax.persistence.Entity;import javax.persistence.Id;import javax.persistence.Table;@Entity@Table(name = "BTSF_BRAND", schema = "hotel")public class Brand {private String id;private String names;private String url;@Id@Column(name = "ID", unique = true, nullable = false, length = 10)public String getId() {return this.id;}public void setId(String id) {this.id = id;}@Column(name = "NAMES", nullable = false, length = 50)public String getNames() {return this.names;}public void setNames(String names) {this.names = names;}@Column(name = "URL", length = 200)public String getUrl() {return this.url;}public void setUrl(String url) {this.url = url;}}

package com.po;import javax.persistence.Column;import javax.persistence.Entity;import javax.persistence.Id;import javax.persistence.Table;@Entity@Table(name = "CITY", schema = "car")public class City {private Integer id;private String name;@Id@Column(name = "ID", unique = true, nullable = false)public Integer getId() {return id;}public void setId(Integer id) {this.id = id;}@Column(name = "NAMES", nullable = false, length = 50)public String getName() {return name;}public void setName(String name) {this.name = name;}}

BrandDaoImpl.java

package com.dao.one;import java.util.List;import javax.annotation.Resource;import org.hibernate.Query;import org.hibernate.SessionFactory;import org.springframework.stereotype.Repository;import com.po.Brand;@Repositorypublic class BrandDaoImpl implements IBrandDao {@Resourceprotected SessionFactory sessionFactory;@SuppressWarnings("unchecked")@Overridepublic List<Brand> findAll() {String hql = "from Brand";Query query = sessionFactory.getCurrentSession().createQuery(hql);return query.list();}}

CityDaoImpl.java

package com.dao.two;import java.util.List;import javax.annotation.Resource;import org.hibernate.Query;import org.hibernate.SessionFactory;import org.springframework.stereotype.Repository;import com.po.City;@Repositorypublic class CityDaoImpl implements ICityDao {@Resourceprivate SessionFactory sessionFactory;@SuppressWarnings("unchecked")@Overridepublic List<City> find() {String hql = "from City";Query query = sessionFactory.getCurrentSession().createQuery(hql);return query.list();}}

DaoTest.java

package com.test;import java.util.List;import javax.annotation.Resource;import org.junit.Test;import org.junit.runner.RunWith;import org.springframework.test.context.ContextConfiguration;import org.springframework.test.context.junit4.SpringJUnit4ClassRunner;import org.springframework.test.context.transaction.TransactionConfiguration;import com.dao.one.IBrandDao;import com.dao.two.ICityDao;import com.po.Brand;import com.po.City;@RunWith(SpringJUnit4ClassRunner.class)@ContextConfiguration(locations = "classpath:com/resource/applicationContext.xml")@TransactionConfiguration(transactionManager = "transactionManager", defaultRollback = false)public class DaoTest {@Resourceprivate IBrandDao brandDao;@Resourceprivate ICityDao cityDao;@Testpublic void testList() {List<Brand> brands = brandDao.findAll();System.out.println(brands.size());List<City> cities = cityDao.find();System.out.println(cities.size());}}

利用aop，达到动态更改数据源的目的。当需要增加数据源的时候，我们只需要在applicationContext配置文件中添加aop配置，新建个DataSourceInterceptor即可。而不需要更改任何代码。