spring動態建立，載入，使用多資料來源
阿新 • • 發佈：2019-02-19
專案中我們經常會遇到多資料來源的問題，尤其是資料同步或定時任務等專案更是如此。多資料來源讓人最頭痛的，不是配置多個數據源，而是如何能靈活動態的切換資料來源。例如在一個spring和hibernate的框架的專案中，我們在spring配置中往往是配置一個dataSource來連線資料庫，然後繫結給sessionFactory，在dao層程式碼中再指定sessionFactory來進行資料庫操作。
正如上圖所示，每一塊都是指定綁死的，如果是多個數據源，也只能是下圖中那種方式。
可看出在Dao層程式碼中寫死了兩個SessionFactory，這樣日後如果再多一個數據源，還要改程式碼新增一個SessionFactory，顯然這並不符合開閉原則。
那麼正確的做法應該是
先說一下我的思路：
首先做一個建立資料來源配置檔案的類，專門用於建立資料來源xml配置，叫ConfigFileCreator.java
其次，編寫一個動態載入剛才建立的配置檔案的類，叫 DynamicLoadBean.java。至此，建立的資料來源到記憶體中已經完成。
第三，重點編寫這個DynamicDataSource.java，該類主要是用來實現動態切換資料來源，並通知容器。在這一塊我選擇了修改，AbstractRoutingDataSource.java，編寫一個支援新增資料來源物件的方法public void addDataSource(Object key,Object dataSource)
第四，寫例子來測試
實現過程如下：
1.bean.xml配置檔案
2.AbstractRoutingDataSource.class 修改的部分<?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"> <!-- 自動掃描與裝配bean --> <context:component-scan base-package="qilin"></context:component-scan> <!-- 使用外部的配置檔案 --> <context:property-placeholder location="classpath:jdbc.properties" /> <bean id="defaultDataSource" class="com.mchange.v2.c3p0.ComboPooledDataSource"> <!-- 資料庫連線資訊 --> <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"> <!-- 資料庫連線資訊 --> <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> <!-- 註解方式配置 --> <property name="annotatedClasses"> <list> <value>qilin.entity.Student</value> </list> </property> </bean> <!-- 配置宣告式事務管理，採用基於註解的方式 --> <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>
/**@author qilin**/
public void addDataSource(Object key,Object dataSource){
this.targetDataSources.put(key, dataSource);
setTargetDataSources(this.targetDataSources);
}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 {
/*
* 該方法必須要重寫 方法是為了根據資料庫標示符取得當前的資料庫
*/
@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);
//重點
super.afterPropertiesSet();
}
}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;
/**
* 動�?�載入資料來源
* @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.配置檔案的位置固�?
* 2.配置檔案中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);
}
}
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.測試程式碼
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);
//建立一個數據源
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);
}
}
切換資料來源就一句話搞定 DataSourceContextHolder.setDataSourceType("qqq");