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

	

	

	
		
			
				classpath:com/resource/config.properties
			
		
	

	
		
		
		
		
		
		
		
	

	
		
		
		
		
		
		
		
	

	
		
			
		
		
		
	

	
		
		
			
				org.hibernate.dialect.MySQLDialect
				org.springframework.orm.hibernate4.SpringSessionContext
				false
				true
				create
			
		
		
			
				com.po
			
		
	

	
		
	

	
		
		
	

	
		
			
			
			
			
			
		
	

	
		
			
			
			
			
		
	

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 contextHolder = new ThreadLocal();

	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 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 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 brands = brandDao.findAll();
		System.out.println(brands.size());

		List 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。

本篇博文中的拦截器dataSourceAspect配置是有问题的，由于咨询动态多数据源的人比较多，我因此做了个demo给大家以供参考，请移步：

Spring动态多数据源实例Demo