前言
上篇文章我觉的使用拦截器虽然方便快捷，但是在使用读串还是写串上你无法控制，我更希望我们像jdbc那样可以手动控制我使用读写串，那么这篇则在sqlsession的基础上实现读写分离， 这种方式则需要手动实现daoImpl。
项目结构
开发环境
SpringMVC+MyBatis+SQL Server2014
实现读写分离
1、关键点是springmvc-servlet.xml中的配置，datasource、sqlsessionfactory、sqlsession
1 <?xml version="1.0" encoding="UTF-8"?> 2 <beans xmlns="http://www.springframework.org/schema/beans" 3 xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" 4 xmlns:mvc="http://www.springframework.org/schema/mvc" 5 xmlns:context="http://www.springframework.org/schema/context" 6 xmlns:tx="http://www.springframework.org/schema/tx" 7 xsi:schemaLocation="http://www.springframework.org/schema/beans 8 http://www.springframework.org/schema/beans/spring-beans.xsd 9 http://www.springframework.org/schema/context 10 http://www.springframework.org/schema/context/spring-context.xsd 11 http://www.springframework.org/schema/mvc 12 http://www.springframework.org/schema/mvc/spring-mvc.xsd 13 http://www.springframework.org/schema/tx 14 http://www.springframework.org/schema/tx/spring-tx.xsd"> 15 16 <!--从配置文件加载数据库信息--> 17 <bean class="org.springframework.beans.factory.config.PropertyPlaceholderConfigurer"> 18 <property name="locations" value="classpath:config/jdbc.properties"/> 19 <property name="fileEncoding" value="UTF-8"/> 20 </bean> 21 22 <!--配置数据源，这里使用Spring默认--> 23 <bean id="dataSource" class="org.springframework.jdbc.datasource.DriverManagerDataSource"> 24 <property name="driverClassName" value="${sqlserver.driver}"/> 25 <property name="url" value="${sqlserver.url}"/> 26 <property name="username" value="${sqlserver.username}"/> 27 <property name="password" value="${sqlserver.password}"/> 28 </bean> 29 30 31 <!--配置sqlSessionFactory--> 32 <bean id="sqlSessionFactory" class="org.mybatis.spring.SqlSessionFactoryBean"> 33 <property name="configLocation" value="classpath:springmvc-mybatis.xml"/> 34 <property name="dataSource" ref="dataSource"/> 35 </bean> 36 37 <!--master--> 38 <bean id="masterSqlSession" class="org.mybatis.spring.SqlSessionTemplate"> 39 <constructor-arg index="0" ref="sqlSessionFactory"/> 40 </bean> 41 42 <!--slave--> 43 <bean id="slaveSqlSession" class="org.mybatis.spring.SqlSessionTemplate"> 44 <constructor-arg index="0" ref="sqlSessionFactory"/> 45 </bean> 46 47 <!--事务管理器 --> 48 <bean id="transactionManager" class="org.springframework.jdbc.datasource.DataSourceTransactionManager"> 49 <property name="dataSource" ref="dataSource"/> 50 </bean> 51 52 <!-- 使用注解事务，需要在Service方法中添加Transactional注解属性 --> 53 <tx:annotation-driven transaction-manager="transactionManager"/> 54 55 <!--扫描Mapper--> 56 <!--<bean class="org.mybatis.spring.mapper.MapperScannerConfigurer">--> 57 <!--<property name="basePackage" value="com.autohome.dao"/>--> 58 <!--</bean>--> 59 60 <!--启用最新的注解器、映射器--> 61 <mvc:annotation-driven/> 62 63 64 <context:component-scan base-package="com.autohome.*"/> 65 66 <!--jsp视图解析器--> 67 <bean class="org.springframework.web.servlet.view.InternalResourceViewResolver"> 68 <property name="prefix" value="/WEB-INF/views/"/> 69 <property name="suffix" value=".jsp"/> 70 </bean> 71 72 </beans>
2、UserMapper.xml。 namespace不再和dao的包名保持一致
<?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="mapper.UserDao"> <select id="listAllUser" resultType="User"> select * from t_userinfo </select> <select id="listPagedUser" resultType="User"> select top ${pageSize} * from t_userinfo where id not in (select top (${pageSize} * (${pageIndex} -1)) id from t_userinfo) </select> <select id="count" resultType="int"> select count(*) from t_userinfo </select> <insert id="insertUser" parameterType="User"> insert into t_userinfo(name,address) VALUES (#{name},#{address}) </insert> <update id="updateUser" parameterType="User"> UPDATE t_userinfo set name=#{name},address=#{address} where id=#{id} </update> <delete id="deleteUser" parameterType="int"> DELETE FROM t_userinfo where id=#{id} </delete> <select id="getUserById" resultType="User" parameterType="int"> select * from t_userinfo where id=#{id} </select> </mapper>
3、UserDao 接口、UserDao实现
public interface UserDao {
List<User> listAllUser();
int insertUser(User user);
User getUserById(int id);
}
@Repository("userDaoImpl")
public class UserDaoImpl implements UserDao {
@Autowired
private SqlSession masterSqlSession;
@Autowired
private SqlSession slaveSqlSession;
public List<User> listAllUser() {
System.out.println("===========slave==========");
return slaveSqlSession.selectList("mapper.UserDao.listAllUser");
}
public int insertUser(User user) {
System.out.println("===========master==========");
return masterSqlSession.insert("mapper.UserDao.insertUser",user);
}
public User getUserById(int id) {
System.out.println("===========slave==========");
return slaveSqlSession.selectOne("mapper.UserDao.getUserById",id);
}
}
4、Serivce
@Service
public class UserService {
@Autowired
@Qualifier("userDaoImpl")
UserDao userDao;
public List<User> listAllUser() {
return userDao.listAllUser();
}
@Transactional
public int insertUser(User user) {
return userDao.insertUser(user);
}
public User getUserById(int id) {
return userDao.getUserById(id);
}
}
总结
在controller中调用service方法时则可以看出当前方法使用的连接串，而且不用去关心sqlsession的打开关闭问题。
补充
一开始只站在demo的角度去想sqlsession主从分离或者读写分离，从实际应用角度的话从datasource就要分开，并且使用不同的读写连接串。那么针对如上的配置就是需要配置read-datasource、write-datasource、readsqlsessionfactory、writesqlsessionfactory、readsqlsession、writesqlsession。