spring多數據源配置

時間 2019-11-13

標籤 spring 數據配置欄目 Spring 简体版

原文原文鏈接

項目中咱們常常會遇到多數據源的問題，尤爲是數據同步或定時任務等項目更是如此。多數據源讓人最頭痛的，不是配置多個數據源，而是如何能靈活動態的切換數據源。例如在一個spring和hibernate的框架的項目中，咱們在spring配置中每每是配置一個dataSource來鏈接數據庫，而後綁定給sessionFactory，在dao層代碼中再指定sessionFactory來進行數據庫操做。java

正如上圖所示，每一塊都是指定綁死的，若是是多個數據源，也只能是下圖中那種方式。spring

可看出在Dao層代碼中寫死了兩個SessionFactory，這樣往後若是再多一個數據源，還要改代碼添加一個SessionFactory，顯然這並不符合開閉原則。sql

那麼正確的作法應該是數據庫

代碼以下：express

1. applicationContext.xmlspring-mvc

<context:annotation-config />mvc

<context:component-scan base-package="com"></context:component-scan>app

<bean class="org.springframework.beans.factory.config.PropertyPlaceholderConfigurer">
  <property name="locations">
   <list>
    <value>classpath:com/resource/config.properties</value>
   </list>
  </property>
</bean>框架

<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>

<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實體類

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，達到動態更改數據源的目的。當須要增長數據源的時候，咱們只須要在applicationContext配置文件中添加aop配置，新建個DataSourceInterceptor便可。而不須要更改任何代碼。

本篇博文中的攔截器dataSourceAspect配置是有問題的，因爲諮詢動態多數據源的人比較多，我所以作了個demo給你們以供參考，請移步：

Spring動態多數據源實例Demo