唯爱小粽子：Spring+Mybatis实现多数据源
在我们的项目开发过程中，经常需要在同一个项目中运用多个数据库中的数据资源，所以我们经常会在同一个项目连接多个数据库进行开发，今天我们来实现一下在Spring+Mybatis框架下实现多数据源的配置：
1、项目准备：
a、项目中所使用的jar包，该项目通过maven进行jar包的引用
<span style="font-size:18px;"><properties>
<org.springframework.version>4.0.0.RELEASE</org.springframework.version>
<javax.servlet.version>2.5</javax.servlet.version>
<com.alibaba.druid.version>0.2.15</com.alibaba.druid.version>
<org.mybatis.mybatis.spring.version>1.2.2</org.mybatis.mybatis.spring.version>
<mysql.connector.java.version>5.1.21</mysql.connector.java.version>
<org.mybatis.version>3.1.1</org.mybatis.version>
</properties>
<dependencies>
<dependency>
<groupId>junit</groupId>
<artifactId>junit</artifactId>
<version>3.8.1</version>
<scope>test</scope>
</dependency>
<dependency>
<groupId>org.springframework</groupId>
<artifactId>spring-web</artifactId>
<version>${org.springframework.version}</version>
</dependency>
<dependency>
<groupId>org.springframework</groupId>
<artifactId>spring-webmvc</artifactId>
<version>${org.springframework.version}</version>
</dependency>
<dependency>
<groupId>javax.servlet</groupId>
<artifactId>servlet-api</artifactId>
<version>${javax.servlet.version}</version>
</dependency>
<dependency>
<groupId>com.alibaba</groupId>
<artifactId>druid</artifactId>
<version>${com.alibaba.druid.version}</version>
</dependency>
<dependency>
<groupId>org.mybatis</groupId>
<artifactId>mybatis-spring</artifactId>
<version>${org.mybatis.mybatis.spring.version}</version>
</dependency>
<dependency>
<groupId>org.springframework</groupId>
<artifactId>spring-jdbc</artifactId>
<version>${org.springframework.version}</version>
</dependency>
<dependency>
<groupId>mysql</groupId>
<artifactId>mysql-connector-java</artifactId>
<version>${mysql.connector.java.version}</version>
</dependency>
<dependency>
<groupId>org.mybatis</groupId>
<artifactId>mybatis</artifactId>
<version>${org.mybatis.version}</version>
</dependency>
<dependency>
<groupId>org.apache.ibatis</groupId>
<artifactId>ibatis-sqlmap</artifactId>
<version>2.3.4.726</version>
</dependency>
</dependencies></span>
b、web.xml的配置
在该项目中，我们虽然配置了DispatcherServlet的上下文springmvc-servlet.xml,但是只是创建了这样的一个空文件，没有进行任何的实用的配置，这是因为我们已经配置了Spring的上下文，而Spring的上下文其实和DispatcherServlet是可以共用同一个上下文的，如果我们分别创建上下文的话容易造成一些不必要的麻烦
<span style="font-size:18px;"><?xml version="1.0" encoding="UTF-8"?>
<web-app version="3.0" xmlns="http://java.sun.com/xml/ns/javaee"
xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
xsi:schemaLocation="http://java.sun.com/xml/ns/javaee
http://java.sun.com/xml/ns/javaee/web-app_3_0.xsd">
<display-name>datacenter</display-name>
<welcome-file-list>
<welcome-file>index.jsp</welcome-file>
</welcome-file-list>
<!-- 加载Spring容器配置 -->
<listener>
<listener-class>org.springframework.web.context.ContextLoaderListener</listener-class>
</listener>
<context-param>
<param-name>contextConfigLocation</param-name>
<param-value>classpath:spring/applicationContext.xml</param-value>
</context-param>
<!-- encode filter -->
<filter>
<filter-name>encodingFilter</filter-name>
<filter-class>org.springframework.web.filter.CharacterEncodingFilter</filter-class>
<init-param>
<param-name>encoding</param-name>
<param-value>UTF-8</param-value>
</init-param>
<init-param>
<param-name>forceEncoding</param-name>
<param-value>true</param-value>
</init-param>
</filter>
<filter-mapping>
<filter-name>encodingFilter</filter-name>
<url-pattern>/*</url-pattern>
</filter-mapping>
<servlet>
<servlet-name>springmvc</servlet-name>
<servlet-class>org.springframework.web.servlet.DispatcherServlet</servlet-class>
<init-param>
<param-name>contextConfigLocation</param-name>
<param-value>/WEB-INF/springmvc-servlet.xml</param-value>
</init-param>
<load-on-startup>1</load-on-startup>
</servlet>
<!-- 页面请求 -->
<servlet-mapping>
<servlet-name>springmvc</servlet-name>
<url-pattern>*.html</url-pattern>
</servlet-mapping>
<!-- ajax请求 -->
<servlet-mapping>
<servlet-name>springmvc</servlet-name>
<url-pattern>*.json</url-pattern>
</servlet-mapping>
</web-app></span>
2、项目结构
我们将两个数据中的各自的东西分别放在两个名字相同的文件夹下，然后通过one和two来进行区分，项目中共用的东西则不进行区分，这里对项目结构中的每一个包的功能进行一个简单的介绍：
a、domainOne和domainTwo分别用来存放两个不同的数据中的想对应的数据库表的实体类
b、mapperOne和mapperTwo分别用来存放与mybatis所使用的sql语句对应的xml文件的同名接口，用来进行Service中的调用
c、serviceOne和serviceTwo分别存放两个数据库表中对应的数据操作的方法和过程，连接controller和mapper
d、Resource中的mapper_one和mapper_two分别用来存放mybatis在查询过程中所使用的sql语句对应的.xml文件
e、spring中的applicationContext.xml文件中主要进行Spring的上下文的配置和初始化信息配置
f、sping中的applicationContext-dataSource.xml主要是对数据库连接信息和mybatis进行相关配置
g、init-config.properties主要用来存放数据库连接变量和连接配置信息
h、mybatis-config-one.xml和mybatis-config-two.xml主要用来配置实体类的别名信息
接下来，我们看一下每一个类和配置信息的具体实现吧
3、项目实现
a、我们按照项目的初始化过程来看一下这些代码，项目启动中首先会进行初始化的是applicationContext.xml文件
<?xml version="1.0" encoding="UTF-8"?>
<beans xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
xmlns:task="http://www.springframework.org/schema/task"
xmlns:context="http://www.springframework.org/schema/context"
xmlns="http://www.springframework.org/schema/beans"
xsi:schemaLocation="http://www.springframework.org/schema/task http://www.springframework.org/schema/task/spring-task-3.2.xsd
http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans-3.2.xsd
http://www.springframework.org/schema/context http://www.springframework.org/schema/context/spring-context-3.2.xsd">
<import resource="classpath:spring/applicationContext-web.xml"/>
<import resource="classpath:spring/applicationContext-dataSource.xml"/>
<context:component-scan base-package="com.quncao.datacenter"/>
<!-- annotation默认的方法映射适配器 -->
<bean id="handlerMapping" class="org.springframework.web.servlet.mvc.annotation.DefaultAnnotationHandlerMapping" />
<bean id="handlerAdapter" class="org.springframework.web.servlet.mvc.annotation.AnnotationMethodHandlerAdapter" />
</beans>
b、接下来上面的applicationContext.xml会分别的去调用applicationContext-web.xml文件和applicationContext-dataSource.xml文件，这里的applicationContext-web.xml主要是对于前端页面相关信息进行了简单的配置：我们这里简单看一下applicationContext-web.xml文件
<?xml version="1.0" encoding="UTF-8"?>
<beans xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
xmlns:beans="http://www.springframework.org/schema/beans" xmlns:mvc="http://www.springframework.org/schema/mvc"
xmlns:aop="http://www.springframework.org/schema/aop" xmlns="http://www.springframework.org/schema/beans"
xsi:schemaLocation="http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans-3.2.xsd
http://www.springframework.org/schema/mvc http://www.springframework.org/schema/mvc/spring-mvc-3.2.xsd http://www.springframework.org/schema/aop http://www.springframework.org/schema/aop/spring-aop.xsd">
<!--前端视图解析-->
<bean class="org.springframework.web.servlet.view.InternalResourceViewResolver">
<property name="order" value="1"/>
<property name="prefix" value="/WEB-INF/views/"/>
<property name="suffix" value=".jsp"/>
</bean>
</beans>
c、接下来我们这个项目的重头戏来了，多数据源的配置主要在applicationContext-dataSource.xml文件中进行配置的，我们现在看一下这个文件的配置过程：
<?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:aop="http://www.springframework.org/schema/aop"
xmlns:tx="http://www.springframework.org/schema/tx"
xmlns:jdbc="http://www.springframework.org/schema/jdbc"
xmlns:context="http://www.springframework.org/schema/context"
xsi:schemaLocation="http://www.springframework.org/schema/context
http://www.springframework.org/schema/context/spring-context-3.0.xsd
http://www.springframework.org/schema/beans
http://www.springframework.org/schema/beans/spring-beans-3.0.xsd
http://www.springframework.org/schema/jdbc
http://www.springframework.org/schema/jdbc/spring-jdbc-3.0.xsd
http://www.springframework.org/schema/tx
http://www.springframework.org/schema/tx/spring-tx-3.0.xsd
http://www.springframework.org/schema/aop
http://www.springframework.org/schema/aop/spring-aop-3.0.xsd">
<bean class="org.springframework.beans.factory.config.PropertyPlaceholderConfigurer">
<property name="locations">
<value>classpath:spring/init-config.properties</value>
</property>
</bean>
<!--数据源1-->
<bean id="dataSourceOne" class="com.alibaba.druid.pool.DruidDataSource" init-method="init" destroy-method="close">
<!--配置基本属性-->
<property name="url" value="${dataSourceOne.url}"/>
<property name="username" value="${dataSourceOne.username}"/>
<property name="password" value="${dataSourceOne.password}"/>
<property name="connectionProperties" value="${dataSourceOne.driver}"/>
<!--配置初始化大小-->
<property name="initialSize" value="1"/>
<property name="minIdle" value="1"/>
<property name="maxActive" value="20"/>
<!--配置获取连接等待超时时间-->
<property name="maxWait" value="60000"/>
<!--配置间隔多久才进行一次检测，检测需要关闭的空闲连接，单位是毫秒-->
<property name="timeBetweenEvictionRunsMillis" value="60000"/>
<!--配置一个连接在池中最小的生存的时间，单位是毫秒-->
<property name="minEvictableIdleTimeMillis" value="30000"/>
<property name="validationQuery" value="SELECT 'x'"/>
<property name="testWhileIdle" value="true"/>
<property name="testOnBorrow" value="false"/>
<property name="testOnReturn" value="false"/>
<!--打开PSCache，并且制定每个连接上PSCache的大小-->
<property name="poolPreparedStatements" value="false"/>
<property name="maxPoolPreparedStatementPerConnectionSize" value="20"/>
<!--配置监控统计拦截的filters-->
<property name="filters" value="stat"/>
</bean>
<!--define the SqlSessionFactory-->
<bean id="sqlSessionFactoryOne" class="org.mybatis.spring.SqlSessionFactoryBean">
<property name="dataSource" ref="dataSourceOne"/>
<property name="configLocation" value="classpath:spring/mybatis-config-one.xml"/>
<property name="mapperLocations" value="classpath:mapper_one/*.xml"/>
</bean>
<bean class="org.mybatis.spring.mapper.MapperScannerConfigurer">
<property name="sqlSessionFactoryBeanName" value="sqlSessionFactoryOne"/>
<property name="basePackage" value="com.quncao.datacenter.mybatis.mapperOne"/>
</bean>
<bean id="transactionManager" class="org.springframework.jdbc.datasource.DataSourceTransactionManager">
<property name="dataSource" ref="dataSourceOne"/>
<qualifier value="dataOne"/>
</bean>
<!--全注解方式，需加上@Transactional-->
<tx:annotation-driven transaction-manager="transactionManager"/>
<!--事务控制的业务方法配置-->
<!-- <tx:advice id="txAdvice" transaction-manager="transactionManager">
<tx:attributes>
<tx:method name="get*" read-only="true"/>
<tx:method name="page*" read-only="true"/>
<tx:method name="list*" read-only="true"/>
<tx:method name="*"/>
</tx:attributes>
</tx:advice> -->
<!--事务控制拦截-->
<!--<aop:config proxy-target-class="true">
<aop:advisor pointcut="execution(* com.quncao.datacenter..*.service.*Service.*(..))" advice-ref="txAdvice"/>
</aop:config> -->
<!-- <context:component-scan base-package="com.quncao.datacenter.mybatis"/>
<context:annotation-config /> -->
<!--数据源2-->
<bean id="dataSourceTwo" class="com.alibaba.druid.pool.DruidDataSource">
<property name="url" value="${dataSourceTwo.url}"/>
<property name="username" value="${dataSourceTwo.username}"/>
<property name="password" value="${dataSourceTwo.password}"/>
<property name="connectionProperties" value="${dataSourceTwo.driver}"/>
<property name="initialSize" value="${initialSize}"/>
<property name="minIdle" value="${minIdle}"/>
<property name="maxActive" value="${maxActive}"/>
<property name="maxWait" value="${maxWait}"/>
<property name="timeBetweenEvictionRunsMillis" value="${timeBetweenEvictionRunsMillis}"/>
<property name="minEvictableIdleTimeMillis" value="${minEvictableIdleTimeMillis}"/>
<property name="validationQuery" value="SELECT 'x'"/>
<property name="testWhileIdle" value="true"/>
<property name="testOnBorrow" value="false"/>
<property name="testOnReturn" value="false"/>
<property name="poolPreparedStatements" value="false"/>
<property name="maxPoolPreparedStatementPerConnectionSize" value="20"/>
<property name="filters" value="stat"/>
</bean>
<bean id="sqlSessionFactoryTwo" class="org.mybatis.spring.SqlSessionFactoryBean">
<property name="dataSource" ref="dataSourceTwo"/>
<property name="configLocation" value="classpath:spring/mybatis-config-two.xml"/>
<property name="mapperLocations" value="classpath:mapper_two/*.xml"/>
</bean>
<bean class="org.mybatis.spring.mapper.MapperScannerConfigurer">
<property name="sqlSessionFactoryBeanName" value="sqlSessionFactoryTwo"/>
<property name="basePackage" value="com.quncao.datacenter.mybatis.mapperTwo"/>
</bean>
<bean id="transactionManagerTwo" class="org.springframework.jdbc.datasource.DataSourceTransactionManager">
<property name="dataSource" ref="dataSourceTwo"/>
<qualifier value="dataTwo"/>
</bean>
<tx:annotation-driven transaction-manager="transactionManagerTwo"/>
</beans>
d、剩下的就是数据库连接信息和初始化配置信息的配置 init-config.properties
<!--数据库连接池配置--> <!--datacenter数据库--> dataSourceOne.driver=com.mysql.jdbc.Driver dataSourceOne.url=jdbc:mysql://127.0.0.1:3306/dataOne dataSourceOne.username=root dataSourceOne.password=root <!--datasystem--> dataSourceTwo.driver=com.mysql.jdbc.Driver dataSourceTwo.url=jdbc:mysql://127.0.0.1:3306/dataTwo dataSourceTwo.username=root dataSourceTwo.password=root <!--公共配置--> initialSize=1 minIdle=1 maxActive=20 maxWait=60000 timeBetweenEvictionRunsMillis=60000 minEvictableIdleTimeMillis=300000
e、最后就是mybatis-config-one.xml和mybatis-config-two.xml文件的配置啦
<?xml version="1.0" encoding="UTF-8"?>
<!DOCTYPE configuration PUBLIC "-//mybatis.org//DTD SQL Map Config 3.0//EN"
"http://mybatis.org/dtd/mybatis-3-config.dtd">
<configuration>
<settings>
<setting name="cacheEnabled" value="false"/>
<setting name="defaultExecutorType" value="REUSE"/>
<setting name="useGeneratedKeys" value="true"/>
</settings>
<typeAliases>
<typeAlias type="com.quncao.datacenter.mybatis.domainOne.TbSystem" alias="TbSystem" />
</typeAliases>
<typeHandlers>
</typeHandlers>
<mappers>
</mappers>
</configuration>
f、现在我们来看一下mapper_one下的SystemMapper.xml文件的内容
<?xml version="1.0" encoding="UTF-8"?>
<!DOCTYPE mapper PUBLIC "-//mybatis.org//DTD Mapper 3.0//EN"
"http://mybatis.org/dtd/mybatis-3-mapper.dtd">
<mapper namespace="com.quncao.datacenter.mybatis.mapperOne.SystemMapper">
<resultMap type="TbSystem" id="TbSystem">
<result property="id" column="id"/>
<result property="name" column="name"/>
<result property="url" column="url"/>
</resultMap>
<select id="getById" parameterType="Integer" resultType="TbSystem">
SELECT * from tb_system where id = #{id}
</select>
</mapper>
g、与SystemMapper.xml想对应的便是和他们名字相同的SystemMapper.java的接口啦
package com.quncao.datacenter.mybatis.mapperOne;
import com.quncao.datacenter.mybatis.domainOne.TbSystem;
/**
* Created by zhang on 16/3/15.
*/
public interface SystemMapper {
TbSystem getById(Integer id);
}
h、调用这个接口的便是我们的service文件，service文件会通过继承BaseService来确定调用哪一个数据中的信息，所以每一个Service文件都需要继承该数据库想对应的父类
我们首先来看一下BaseServiceOne.java中的内容，该类为一个抽象类，只要目的是为了通过注解的方式确定数据源和数据的回滚
package com.quncao.datacenter.mybatis.serviceOne;
import org.springframework.transaction.annotation.Transactional;
/**
* Created by zhang on 16/3/15.
*/
@Transactional(value="dataOne",rollbackFor = Exception.class)
public abstract class BaseServiceOne {
}
接下来是具体的SystemService.java的实现
package com.quncao.datacenter.mybatis.serviceOne;
import com.quncao.datacenter.mybatis.domainOne.TbSystem;
import com.quncao.datacenter.mybatis.mapperOne.SystemMapper;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.stereotype.Service;
/**
* Created by zhang on 16/3/15.
*/
@Service("systemService")
public class SystemService extends BaseServiceOne {
@Autowired
private SystemMapper systemMapper;
public TbSystem getById(int id){
return systemMapper.getById(id);
}
}
最后就是Controller的实现啦
package com.quncao.datacenter.controller;
import com.quncao.datacenter.mybatis.domainOne.TbSystem;
import com.quncao.datacenter.mybatis.domainTwo.TbUser;
import com.quncao.datacenter.mybatis.mapperTwo.UserMapper;
import com.quncao.datacenter.mybatis.serviceOne.SystemService;
import com.quncao.datacenter.mybatis.serviceTwo.UserService;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.stereotype.Controller;
import org.springframework.ui.ModelMap;
import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.servlet.ModelAndView;
import javax.servlet.http.HttpServletRequest;
/**
* Created by zhang on 16/3/14.
*/
@Controller()
@RequestMapping("system")
public class SystemController {
@Autowired
private SystemService systemService;
@Autowired
private UserService userService;
/**
* 登录预加载
* @return
*/
@RequestMapping("preLogin")
public ModelAndView preLogin(){
ModelAndView mav = new ModelAndView();
ModelMap mm = mav.getModelMap();
mm.put("message","");
mav.setViewName("login");
return mav;
}
@RequestMapping("login")
public ModelAndView login(HttpServletRequest request){
ModelAndView mav = new ModelAndView();
ModelMap mm = mav.getModelMap();
String username = request.getParameter("username");
String password = request.getParameter("password");
if(username!=null && !"".equals(username)){
TbUser user = userService.getUserByName(username);
if (user != null) {
if(password.equals(user.getPassword())){
try {
mm.put("message","欢迎您的登录");
mm.put("user",user);
TbSystem system = systemService.getById(1);
mm.put("system",system);
} catch (Exception e ) {
e.printStackTrace();
}
mav.setViewName("main");
}else{
mm.put("message","您输入的用户名或者密码错误");
mav.setViewName("login");
}
}else{
mm.put("message","该用户不存在");
mav.setViewName("login");
}
}
return mav;
}
}
这样，一个基于Spring和Mybatis框架进行的多数据源的框架就这样实现了，在这个创建的过程中一定会有各种各样的困难，其实在我们克服这些困难的过程正是我们掌握技能的过程，祝大家成功