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

  1 <?xml version="1.0" encoding="UTF-8"?>
  2 <beans xmlns="http://www.springframework.org/schema/beans"
  3     xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xmlns:aop="http://www.springframework.org/schema/aop"
  4     xmlns:cache="http://www.springframework.org/schema/cache"
  5     xmlns:context="http://www.springframework.org/schema/context"
  6     xmlns:jdbc="http://www.springframework.org/schema/jdbc" xmlns:jee="http://www.springframework.org/schema/jee"
  7     xmlns:jms="http://www.springframework.org/schema/jms" xmlns:lang="http://www.springframework.org/schema/lang"
  8     xmlns:mvc="http://www.springframework.org/schema/mvc" xmlns:oxm="http://www.springframework.org/schema/oxm"
  9     xmlns:p="http://www.springframework.org/schema/p" xmlns:task="http://www.springframework.org/schema/task"
 10     xmlns:tx="http://www.springframework.org/schema/tx" xmlns:util="http://www.springframework.org/schema/util"
 11     xsi:schemaLocation="http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans.xsd  
 12     http://www.springframework.org/schema/aop http://www.springframework.org/schema/aop/spring-aop-3.1.xsd  
 13        http://www.springframework.org/schema/cache http://www.springframework.org/schema/cache/spring-cache-3.1.xsd  
 14     http://www.springframework.org/schema/context http://www.springframework.org/schema/context/spring-context-3.1.xsd  
 15     http://www.springframework.org/schema/jdbc http://www.springframework.org/schema/jdbc/spring-jdbc-3.1.xsd  
 16     http://www.springframework.org/schema/jee http://www.springframework.org/schema/jee/spring-jee-3.1.xsd  
 17     http://www.springframework.org/schema/jms http://www.springframework.org/schema/jms/spring-jms-3.1.xsd  
 18       http://www.springframework.org/schema/lang http://www.springframework.org/schema/lang/spring-lang-3.1.xsd  
 19        http://www.springframework.org/schema/mvc http://www.springframework.org/schema/mvc/spring-mvc-3.1.xsd  
 20       http://www.springframework.org/schema/oxm http://www.springframework.org/schema/oxm/spring-oxm-3.1.xsd  
 21      http://www.springframework.org/schema/task http://www.springframework.org/schema/task/spring-task-3.1.xsd  
 22     http://www.springframework.org/schema/tx http://www.springframework.org/schema/tx/spring-tx-3.1.xsd  
 23     http://www.springframework.org/schema/util http://www.springframework.org/schema/util/spring-util-3.1.xsd">
 24 
 25     <context:annotation-config />
 26 
 27     <context:component-scan base-package="com"></context:component-scan>
 28 
 29     <bean class="org.springframework.beans.factory.config.PropertyPlaceholderConfigurer">
 30         <property name="locations">
 31             <list>
 32                 <value>classpath:com/resource/config.properties</value>
 33             </list>
 34         </property>
 35     </bean>
 36 
 37     <bean id="dataSourceOne" class="com.mchange.v2.c3p0.ComboPooledDataSource"
 38         destroy-method="close">
 39         <property name="driverClass" value="${dbOne.jdbc.driverClass}" />
 40         <property name="jdbcUrl" value="${dbOne.jdbc.url}" />
 41         <property name="user" value="${dbOne.jdbc.user}" />
 42         <property name="password" value="${dbOne.jdbc.password}" />
 43         <property name="initialPoolSize" value="${dbOne.jdbc.initialPoolSize}" />
 44         <property name="minPoolSize" value="${dbOne.jdbc.minPoolSize}" />
 45         <property name="maxPoolSize" value="${dbOne.jdbc.maxPoolSize}" />
 46     </bean>
 47 
 48     <bean id="dataSourceTwo" class="com.mchange.v2.c3p0.ComboPooledDataSource"
 49         destroy-method="close">
 50         <property name="driverClass" value="${dbTwo.jdbc.driverClass}" />
 51         <property name="jdbcUrl" value="${dbTwo.jdbc.url}" />
 52         <property name="user" value="${dbTwo.jdbc.user}" />
 53         <property name="password" value="${dbTwo.jdbc.password}" />
 54         <property name="initialPoolSize" value="${dbTwo.jdbc.initialPoolSize}" />
 55         <property name="minPoolSize" value="${dbTwo.jdbc.minPoolSize}" />
 56         <property name="maxPoolSize" value="${dbTwo.jdbc.maxPoolSize}" />
 57     </bean>
 58 
 59     <bean id="dynamicDataSource" class="com.core.DynamicDataSource">
 60         <property name="targetDataSources">
 61             <map key-type="java.lang.String">
 62                 <entry value-ref="dataSourceOne" key="dataSourceOne"></entry>
 63                 <entry value-ref="dataSourceTwo" key="dataSourceTwo"></entry>
 64             </map>
 65         </property>
 66         <property name="defaultTargetDataSource" ref="dataSourceOne">
 67         </property>
 68     </bean>
 69 
 70     <bean id="sessionFactory" class="org.springframework.orm.hibernate4.LocalSessionFactoryBean">
 71         <property name="dataSource" ref="dynamicDataSource" />
 72         <property name="hibernateProperties">
 73             <props>
 74                 <prop key="hibernate.dialect">org.hibernate.dialect.MySQLDialect</prop>
 75                 <prop key="hibernate.current_session_context_class">org.springframework.orm.hibernate4.SpringSessionContext</prop>
 76                 <prop key="hibernate.show_sql">false</prop>
 77                 <prop key="hibernate.format_sql">true</prop>
 78                 <prop key="hbm2ddl.auto">create</prop>
 79             </props>
 80         </property>
 81         <property name="packagesToScan">
 82             <list>
 83                 <value>com.po</value>
 84             </list>
 85         </property>
 86     </bean>
 87 
 88     <bean id="transactionManager" class="org.springframework.orm.hibernate4.HibernateTransactionManager">
 89         <property name="sessionFactory" ref="sessionFactory" />
 90     </bean>
 91 
 92     <aop:config>
 93         <aop:pointcut id="transactionPointCut" expression="execution(* com.dao..*.*(..))" />
 94         <aop:advisor advice-ref="txAdvice" pointcut-ref="transactionPointCut" />
 95     </aop:config>
 96 
 97     <tx:advice id="txAdvice" transaction-manager="transactionManager">
 98         <tx:attributes>
 99             <tx:method name="add*" propagation="REQUIRED" />
100             <tx:method name="save*" propagation="REQUIRED" />
101             <tx:method name="update*" propagation="REQUIRED" />
102             <tx:method name="delete*" propagation="REQUIRED" />
103             <tx:method name="*" read-only="true" />
104         </tx:attributes>
105     </tx:advice>
106 
107     <aop:config>
108         <aop:aspect id="dataSourceAspect" ref="dataSourceInterceptor">
109             <aop:pointcut id="daoOne" expression="execution(* com.dao.one.*.*(..))" />
110             <aop:pointcut id="daoTwo" expression="execution(* com.dao.two.*.*(..))" />
111             <aop:before pointcut-ref="daoOne" method="setdataSourceOne" />
112             <aop:before pointcut-ref="daoTwo" method="setdataSourceTwo" />
113         </aop:aspect>
114     </aop:config>
115 </beans>

2. DynamicDataSource.class

 1 package com.core;
 2 
 3 import org.springframework.jdbc.datasource.lookup.AbstractRoutingDataSource;
 4 
 5 public class DynamicDataSource extends AbstractRoutingDataSource{
 6 
 7     @Override
 8     protected Object determineCurrentLookupKey() {
 9         return DatabaseContextHolder.getCustomerType(); 
10     }
11 
12 }

3. DatabaseContextHolder.class

 1 package com.core;
 2 
 3 public class DatabaseContextHolder {
 4 
 5     private static final ThreadLocal<String> contextHolder = new ThreadLocal<String>();
 6 
 7     public static void setCustomerType(String customerType) {
 8         contextHolder.set(customerType);
 9     }
10 
11     public static String getCustomerType() {
12         return contextHolder.get();
13     }
14 
15     public static void clearCustomerType() {
16         contextHolder.remove();
17     }
18 }

4. DataSourceInterceptor.class

 1 package com.core;
 2 
 3 import org.aspectj.lang.JoinPoint;
 4 import org.springframework.stereotype.Component;
 5 
 6 @Component
 7 public class DataSourceInterceptor {
 8 
 9     public void setdataSourceOne(JoinPoint jp) {
10         DatabaseContextHolder.setCustomerType("dataSourceOne");
11     }
12     
13     public void setdataSourceTwo(JoinPoint jp) {
14         DatabaseContextHolder.setCustomerType("dataSourceTwo");
15     }
16 }

5. po实体类

 1 package com.po;
 2 
 3 import javax.persistence.Column;
 4 import javax.persistence.Entity;
 5 import javax.persistence.Id;
 6 import javax.persistence.Table;
 7 
 8 @Entity
 9 @Table(name = "BTSF_BRAND", schema = "hotel")
10 public class Brand {
11 
12     private String id;
13     private String names;
14     private String url;
15 
16     @Id
17     @Column(name = "ID", unique = true, nullable = false, length = 10)
18     public String getId() {
19         return this.id;
20     }
21 
22     public void setId(String id) {
23         this.id = id;
24     }
25 
26     @Column(name = "NAMES", nullable = false, length = 50)
27     public String getNames() {
28         return this.names;
29     }
30 
31     public void setNames(String names) {
32         this.names = names;
33     }
34 
35     @Column(name = "URL", length = 200)
36     public String getUrl() {
37         return this.url;
38     }
39 
40     public void setUrl(String url) {
41         this.url = url;
42     }
43 }

 1 package com.po;
 2 
 3 import javax.persistence.Column;
 4 import javax.persistence.Entity;
 5 import javax.persistence.Id;
 6 import javax.persistence.Table;
 7 
 8 @Entity
 9 @Table(name = "CITY", schema = "car")
10 public class City {
11 
12     private Integer id;
13     
14     private String name;
15 
16     @Id
17     @Column(name = "ID", unique = true, nullable = false)
18     public Integer getId() {
19         return id;
20     }
21 
22     public void setId(Integer id) {
23         this.id = id;
24     }
25 
26     @Column(name = "NAMES", nullable = false, length = 50)
27     public String getName() {
28         return name;
29     }
30 
31     public void setName(String name) {
32         this.name = name;
33     }
34 }

6. BrandDaoImpl.class

 1 package com.dao.one;
 2 
 3 import java.util.List;
 4 
 5 import javax.annotation.Resource;
 6 
 7 import org.hibernate.Query;
 8 import org.hibernate.SessionFactory;
 9 import org.springframework.stereotype.Repository;
10 
11 import com.po.Brand;
12 
13 @Repository
14 public class BrandDaoImpl implements IBrandDao {
15 
16     @Resource
17     protected SessionFactory sessionFactory;
18 
19     @SuppressWarnings("unchecked")
20     @Override
21     public List<Brand> findAll() {
22         String hql = "from Brand";
23         Query query = sessionFactory.getCurrentSession().createQuery(hql);
24         return query.list();
25     }
26 }

7. CityDaoImpl.class

 1 package com.dao.two;
 2 
 3 import java.util.List;
 4 
 5 import javax.annotation.Resource;
 6 
 7 import org.hibernate.Query;
 8 import org.hibernate.SessionFactory;
 9 import org.springframework.stereotype.Repository;
10 
11 import com.po.City;
12 
13 @Repository
14 public class CityDaoImpl implements ICityDao {
15 
16     @Resource
17     private SessionFactory sessionFactory;
18 
19     @SuppressWarnings("unchecked")
20     @Override
21     public List<City> find() {
22         String hql = "from City";
23         Query query = sessionFactory.getCurrentSession().createQuery(hql);
24         return query.list();
25     }
26 }

8. DaoTest.class

 1 package com.test;
 2 
 3 import java.util.List;
 4 
 5 import javax.annotation.Resource;
 6 
 7 import org.junit.Test;
 8 import org.junit.runner.RunWith;
 9 import org.springframework.test.context.ContextConfiguration;
10 import org.springframework.test.context.junit4.SpringJUnit4ClassRunner;
11 import org.springframework.test.context.transaction.TransactionConfiguration;
12 
13 import com.dao.one.IBrandDao;
14 import com.dao.two.ICityDao;
15 import com.po.Brand;
16 import com.po.City;
17 
18 @RunWith(SpringJUnit4ClassRunner.class)
19 @ContextConfiguration(locations = "classpath:com/resource/applicationContext.xml")
20 @TransactionConfiguration(transactionManager = "transactionManager", defaultRollback = false)
21 public class DaoTest {
22 
23     @Resource
24     private IBrandDao brandDao;
25 
26     @Resource
27     private ICityDao cityDao;
28 
29     @Test
30     public void testList() {
31         List<Brand> brands = brandDao.findAll();
32         System.out.println(brands.size());
33 
34         List<City> cities = cityDao.find();
35         System.out.println(cities.size());
36     }
37 }

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。