spring多数据源配置

原文：http://blog.csdn.net/wangpeng047/article/details/8866239

spring多数据源配置

分类： java spring 数据库 项目经验 2013-04-29 16:48  5658人阅读  评论(10)  收藏  举报

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>

     <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>

     <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>
 </beans>

2. DynamicDataSource.class

 package com.core;

 import org.springframework.jdbc.datasource.lookup.AbstractRoutingDataSource;

 public class DynamicDataSource extends AbstractRoutingDataSource{

     @Override
     protected Object determineCurrentLookupKey() {
         return DatabaseContextHolder.getCustomerType();
     }

 }

3. DatabaseContextHolder.class

 package com.core;

 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. DataSourceInterceptor.class

 package com.core;

 import org.aspectj.lang.JoinPoint;
 import org.springframework.stereotype.Component;

 @Component
 public class DataSourceInterceptor {

     public void setdataSourceOne(JoinPoint jp) {
         DatabaseContextHolder.setCustomerType("dataSourceOne");
     }

     public void setdataSourceTwo(JoinPoint jp) {
         DatabaseContextHolder.setCustomerType("dataSourceTwo");
     }
 }

5. 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;
     }
 }

6. BrandDaoImpl.class

 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;

 @Repository
 public class BrandDaoImpl implements IBrandDao {

     @Resource
     protected SessionFactory sessionFactory;

     @SuppressWarnings("unchecked")
     @Override
     public List<Brand> findAll() {
         String hql = "from Brand";
         Query query = sessionFactory.getCurrentSession().createQuery(hql);
         return query.list();
     }
 }

7. CityDaoImpl.class

 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;

 @Repository
 public class CityDaoImpl implements ICityDao {

     @Resource
     private SessionFactory sessionFactory;

     @SuppressWarnings("unchecked")
     @Override
     public List<City> find() {
         String hql = "from City";
         Query query = sessionFactory.getCurrentSession().createQuery(hql);
         return query.list();
     }
 }

8. DaoTest.class

 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 {

     @Resource
     private IBrandDao brandDao;

     @Resource
     private ICityDao cityDao;

     @Test
     public 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。