http://blog.csdn.net/qilin18/article/details/17614005
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
先说一下我的思路:
首先做一个创建数据源配置文件的类,专门用于创建数据源xml配置,叫ConfigFileCreator.java
其次,编写一个动态加载刚才创建的配置文件的类,叫 DynamicLoadBean.java。至此,创建的数据源到内存中已经完成。
第三,重点编写这个DynamicDataSource.java,该类主要是用来实现动态切换数据源,并通知容器。在这一块我选择了修改,AbstractRoutingDataSource.java,编写一个支持添加数据源对象的方法public void addDataSource(Object key,Object dataSource)
第四,写例子来测试
实现过程如下:
1.bean.xml配置文件
- <?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:tx="http://www.springframework.org/schema/tx"
- xmlns:context="http://www.springframework.org/schema/context"
- 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://www.springframework.org/schema/tx http://www.springframework.org/schema/tx/spring-tx-3.0.xsd">
- <!-- 自动扫描与装配bean -->
- <context:component-scan base-package="qilin"></context:component-scan>
- <!-- 使用外部的配置文件 -->
- <context:property-placeholder location="classpath:jdbc.properties" />
- <bean id="defaultDataSource" class="com.mchange.v2.c3p0.ComboPooledDataSource">
- <!-- 数据库连接信息 -->
- <property name="jdbcUrl" value="${jdbcUrl}"></property>
- <property name="driverClass" value="${driverClass}"></property>
- <property name="user" value="${username}"></property>
- <property name="password" value="${password}"></property>
- </bean>
- <bean id="dataSourceA" class="com.mchange.v2.c3p0.ComboPooledDataSource">
- <!-- 数据库连接信息 -->
- <property name="jdbcUrl" value="jdbc:mysql:///dynamictest"></property>
- <property name="driverClass" value="${driverClass}"></property>
- <property name="user" value="${username}"></property>
- <property name="password" value="${password}"></property>
- </bean>
- <bean id="dynamicdatasource" class="qilin.utils.DynamicDataSource">
- <property name="targetDataSources">
- <map key-type="java.lang.String">
- <entry key="defaultDataSource" value-ref="defaultDataSource" />
- <entry key="dataSourceA" value-ref="dataSourceA" />
- </map>
- </property>
- <property name="defaultTargetDataSource" ref="defaultDataSource" />
- </bean>
- <!-- 配置SessionFactory -->
- <bean id="sessionFactory"
- class="org.springframework.orm.hibernate3.annotation.AnnotationSessionFactoryBean">
- <property name="dataSource" ref="dynamicdatasource" />
- <property name="hibernateProperties">
- <props>
- <prop key="hibernate.dialect">org.hibernate.dialect.MySQLDialect</prop>
- <prop key="hibernate.hbm2ddl.auto">none</prop>
- <prop key="hibernate.show_sql">true</prop>
- <prop key="hibernate.format_sql">false</prop>
- <prop key="hibernate.temp.use_jdbc_metadata_defaults">false</prop>
- </props>
- </property>
- <!-- 注解方式配置 -->
- <property name="annotatedClasses">
- <list>
- <value>qilin.entity.Student</value>
- </list>
- </property>
- </bean>
- <!-- 配置声明式事务管理,采用基于注解的方式 -->
- <bean id="transactionManager"
- class="org.springframework.orm.hibernate3.HibernateTransactionManager">
- <property name="sessionFactory" ref="sessionFactory"></property>
- </bean>
- <tx:annotation-driven transaction-manager="transactionManager" />
- <bean id="dynamicLoadBean" class="qilin.utils.DynamicLoadBean"></bean>
- </beans>
2.AbstractRoutingDataSource.class 修改的部分
- /**@author qilin**/
- public void addDataSource(Object key,Object dataSource){
- this.targetDataSources.put(key, dataSource);
- setTargetDataSources(this.targetDataSources);
- }
3.DynamicDataSource.class 这个类中有一个地方需要注意,当我们添加数据,切换了数据源,要通知当前spring容器,需要调用父类的super.afterPropertiesSet();方法
- package qilin.utils;
- import java.util.Map;
- import org.springframework.jdbc.datasource.lookup.AbstractRoutingDataSource;
- import org.springframework.jdbc.datasource.lookup.DataSourceLookup;
- public class DynamicDataSource extends AbstractRoutingDataSource {
- /*
- * 该方法必须要重写 方法是为了根据数据库标示符取得当前的数据库
- */
- @Override
- public Object determineCurrentLookupKey() {
- return DataSourceContextHolder.getDataSourceName();
- }
- @Override
- public void setDataSourceLookup(DataSourceLookup dataSourceLookup) {
- super.setDataSourceLookup(dataSourceLookup);
- }
- @Override
- public void setDefaultTargetDataSource(Object defaultTargetDataSource) {
- super.setDefaultTargetDataSource(defaultTargetDataSource);
- }
- @Override
- public void setTargetDataSources(Map targetDataSources) {
- super.setTargetDataSources(targetDataSources);
- //重点
- super.afterPropertiesSet();
- }
- }
4.动态加载数据源配置文件DynamicLoadBean.class
- package qilin.utils;
- import java.io.IOException;
- import org.springframework.beans.BeansException;
- import org.springframework.beans.factory.config.BeanDefinition;
- import org.springframework.beans.factory.support.BeanDefinitionRegistry;
- import org.springframework.beans.factory.support.ChildBeanDefinition;
- import org.springframework.beans.factory.support.DefaultListableBeanFactory;
- import org.springframework.beans.factory.xml.ResourceEntityResolver;
- import org.springframework.beans.factory.xml.XmlBeanDefinitionReader;
- import org.springframework.context.ApplicationContext;
- import org.springframework.context.ApplicationContextAware;
- import org.springframework.context.ConfigurableApplicationContext;
- /**
- * 动�?�加载数据源
- * @author qilin
- *
- */
- public class DynamicLoadBean implements ApplicationContextAware {
- private ConfigurableApplicationContext applicationContext = null;
- public void setApplicationContext(ApplicationContext applicationContext)
- throws BeansException {
- this.applicationContext = (ConfigurableApplicationContext) applicationContext;
- }
- public ConfigurableApplicationContext getApplicationContext() {
- return applicationContext;
- }
- /**
- * 1.配置文件的位置固�?
- * 2.配置文件中bean的名字已�?
- * @param configLocationString
- */
- public void loadBean(String fileName)
- {
- XmlBeanDefinitionReader beanDefinitionReader = new XmlBeanDefinitionReader((BeanDefinitionRegistry)getApplicationContext().getBeanFactory());
- beanDefinitionReader.setResourceLoader(getApplicationContext());
- beanDefinitionReader.setEntityResolver(new ResourceEntityResolver(getApplicationContext()));
- try
- {
- beanDefinitionReader.loadBeanDefinitions(getApplicationContext().getResources(fileName));
- } catch (BeansException e) {
- e.printStackTrace();
- } catch (IOException e) {
- e.printStackTrace();
- }
- }
- public void registBean(String beanName, String parentName) {
- DefaultListableBeanFactory fcy = (DefaultListableBeanFactory)applicationContext.getAutowireCapableBeanFactory();
- BeanDefinition beanDefinition = new ChildBeanDefinition(parentName);
- fcy.registerBeanDefinition(beanName, beanDefinition);
- }
- }
5.DataSourceContextHolder.class
- package qilin.utils;
- public class DataSourceContextHolder {
- private static final ThreadLocal contextHolder=new ThreadLocal();
- public static void setDataSourceType(String dataSourceName){
- contextHolder.set(dataSourceName);
- }
- public static String getDataSourceName(){
- return (String) contextHolder.get();
- }
- public static void clearDataSourceType(){
- contextHolder.remove();
- }
- }
5.测试代码
- package junit;
- import java.util.HashMap;
- import java.util.Map;
- import org.springframework.context.ApplicationContext;
- import org.springframework.context.support.ClassPathXmlApplicationContext;
- import com.mchange.v2.c3p0.ComboPooledDataSource;
- import qilin.entity.Student;
- import qilin.service.StuService;
- import qilin.utils.DataSourceContextHolder;
- import qilin.utils.DynamicDataSource;
- import qilin.utils.DynamicLoadBean;
- public class Test {
- public static void main(String[] args) {
- ApplicationContext ac = new ClassPathXmlApplicationContext("bean.xml");
- StuService stuService = (StuService) ac.getBean("stuServiceImpl");
- Student stu = new Student();
- stu.setStuName("qilin");
- stuService.save(stu);
- DataSourceContextHolder.setDataSourceType("dataSourceA");
- Student _stu = new Student();
- _stu.setStuName("_qilin1");
- stuService.save(_stu);
- //创建一个数据源
- DynamicLoadBean dynamicBeanLoad =(DynamicLoadBean)ac.getBean("dynamicLoadBean");
- dynamicBeanLoad.loadBean("classpath:mos/qqq.xml");
- ComboPooledDataSource dataSource = (ComboPooledDataSource) ac.getBean("qqq");
- System.err.println(dataSource.getDriverClass());
- DynamicDataSource dynamicDataSource = (DynamicDataSource) ac.getBean("dynamicdatasource");
- // Map<String, ComboPooledDataSource> targetDataSources = new HashMap<String, ComboPooledDataSource>();
- // targetDataSources.put("qqq", dataSource);
- // Map<Object, Object> targetDataSources = dynamicDataSource.getTargetDataSources();
- // targetDataSources.put("qqq", dataSource);
- // dynamicDataSource.setTargetDataSources(targetDataSources);
- // dynamicDataSource.setDefaultTargetDataSource(dataSource);
- dynamicDataSource.addDataSource("qqq", dataSource);
- DataSourceContextHolder.setDataSourceType("qqq");
- Student __stu = new Student();
- __stu.setStuName("qilin2");
- stuService.save(__stu);
- }
- }
切换数据源就一句话搞定 DataSourceContextHolder.setDataSourceType("qqq");
下载链接http://download.csdn.net/detail/qi_lin70/6778247