MyBatis在Spring中的事务管理

项目中常常遇到MyBatis与Spring的组合开发，而且相应的事务管理交给Spring。今天我这里记录一下Spring中Mybatis的事务管理。

先看代码：

spring-context.xml

<?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:context="http://www.springframework.org/schema/context"
       xmlns:aop="http://www.springframework.org/schema/aop" xmlns:tx="http://www.springframework.org/schema/tx"
       xsi:schemaLocation="http://www.springframework.org/schema/beans
       http://www.springframework.org/schema/beans/spring-beans.xsd
       http://www.springframework.org/schema/context
       http://www.springframework.org/schema/context/spring-context.xsd http://www.springframework.org/schema/aop http://www.springframework.org/schema/aop/spring-aop.xsd http://www.springframework.org/schema/tx http://www.springframework.org/schema/tx/spring-tx.xsd">
    <!--开启注解-->
    <context:annotation-config/>
    <!--加载属性文件-->
    <bean class="org.springframework.beans.factory.config.PropertyPlaceholderConfigurer">
        <property name="locations">
            <list>
                <value>classpath:db.properties</value>
            </list>
        </property>
    </bean>
    <!--扫描组建-->
    <context:component-scan base-package="com.xwszt.txdemo"/>
    <!--开启事务注解-->
    <tx:annotation-driven transaction-manager="transactionManager"/>

    <aop:aspectj-autoproxy proxy-target-class="true"/>

    <!--配置数据源-->
    <bean id="dataSource" class="com.mchange.v2.c3p0.ComboPooledDataSource">
        <property name="driverClass" value="${jdbc.driver}"/>
        <property name="jdbcUrl" value="${mysql.jdbc.url}"/>
        <property name="user" value="${mysql.jdbc.user}"/>
        <property name="password" value="${mysql.jdbc.password}"/>
        <!--Connection Pooling Info -->
        <property name="initialPoolSize" value="3"/>
        <property name="minPoolSize" value="2"/>
        <property name="maxPoolSize" value="15"/>
        <property name="acquireIncrement" value="3"/>
        <property name="maxStatements" value="8"/>
        <property name="maxStatementsPerConnection" value="5"/>
        <property name="maxIdleTime" value="1800"/>
        <property name="autoCommitOnClose" value="false"/>
    </bean>

    <!--mybatis配置-->
    <bean id="sqlSessionFactory" class="org.mybatis.spring.SqlSessionFactoryBean">
        <property name="dataSource" ref="dataSource"/>
        <property name="mapperLocations" value="classpath:mapper/*"/>
    </bean>
    <!--mybatis扫描mapper对应类的配置-->
    <bean class="org.mybatis.spring.mapper.MapperScannerConfigurer">
        <property name="basePackage" value="com.xwszt.txdemo.dao"/>
        <property name="sqlSessionFactoryBeanName" value="sqlSessionFactory"/>
    </bean>
    <!--事务配置-->
    <bean id="transactionManager" class="org.springframework.jdbc.datasource.DataSourceTransactionManager">
        <property name="dataSource" ref="dataSource"/>
    </bean>
</beans>

db.properties

##mysql
jdbc.driver=com.mysql.jdbc.Driver
mysql.jdbc.url=jdbc:mysql://localhost:3306/demo?useUnicode=true&characterEncoding=UTF-8&useSSL=false&useAffectedRows=true&allowPublicKeyRetrieval=true
mysql.jdbc.user=root
mysql.jdbc.password=*********(这里根据本身修改）

db.sql

SET NAMES utf8mb4;
SET FOREIGN_KEY_CHECKS = 0;

-- ----------------------------
-- Table structure for user
-- ----------------------------
DROP TABLE IF EXISTS `user`;
CREATE TABLE `user` (
  `id` int(10) unsigned NOT NULL AUTO_INCREMENT,
  `username` varchar(50) DEFAULT NULL,
  `password` varchar(50) DEFAULT NULL,
  `salt` varchar(50) DEFAULT NULL,
  `sex` varchar(10) DEFAULT NULL,
  `address` varchar(50) DEFAULT NULL,
  `cellphone` varchar(30) DEFAULT NULL,
  `email` varchar(30) DEFAULT NULL,
  `islock` smallint(1) unsigned NOT NULL DEFAULT '0',
  `isvalidate` smallint(1) unsigned NOT NULL DEFAULT '1',
  `isdel` smallint(1) unsigned NOT NULL DEFAULT '0',
  PRIMARY KEY (`id`)
) ENGINE=InnoDB AUTO_INCREMENT=124 DEFAULT CHARSET=utf8mb4 COLLATE=utf8mb4_0900_ai_ci;

SET FOREIGN_KEY_CHECKS = 1

UserDAO.xml

<?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.xwszt.txdemo.dao.UserDAO">
    <insert id="insert" parameterType="com.xwszt.txdemo.entities.User">
        insert into `user`
        (`id`, `username`, `password`, `salt`, `sex`, `address`, `cellphone`, `email`, `islock`,`isvalidate`,`isdel`)
        values
        (#{id}, #{username},#{password},#{salt},#{sex},#{address},#{cellphone},#{email},#{lock},#{validate},#{del})
    </insert>
</mapper>

UserDAO.java

package com.xwszt.txdemo.dao;

import com.xwszt.txdemo.entities.User;

public interface UserDAO {
    void insert(User user);
}

User.java

package com.xwszt.txdemo.entities;

import lombok.Data;

import java.io.Serializable;

@Data
public class User implements Serializable {
    private Long id;
    private String username;
    private String password;
    private String salt;
    private String sex;
    private String address;
    private String cellphone;
    private String email;
    private boolean lock;
    private boolean validate;
    private boolean del;
}

UserService.java

package com.xwszt.txdemo.service;

public interface UserService {
    void doSomething()  throws Exception;
    boolean saveUser() throws Exception;
}

UserServiceImpl.java

package com.xwszt.txdemo.service.impl;

import com.xwszt.txdemo.dao.UserDAO;
import com.xwszt.txdemo.entities.User;
import com.xwszt.txdemo.service.UserService;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.stereotype.Service;
import org.springframework.transaction.annotation.Transactional;

@Service
public class UserServiceImpl implements UserService {

    @Autowired
    private UserService target;

    @Autowired
    private UserDAO userDAO;

    @Override
    public void doSomething() throws Exception {
        target.saveUser();

    }

    @Transactional
    @Override
    public boolean saveUser() throws Exception {

        User user = new User();
        user.setId(123l);
        user.setUsername("zhangsan");
        user.setPassword("123");
        user.setSalt("456");
        user.setSex("FEMAIL");
        user.setAddress("上海市张江高科");
        user.setCellphone("13582911229");
        user.setEmail("978732467@qq.com");
        user.setLock(false);
        user.setValidate(true);
        user.setDel(false);

        userDAO.insert(user);
        
        return true;
    }
}

UserTest.java

package com.xwszt.txdemo;

import com.xwszt.txdemo.service.UserService;
import org.junit.Test;
import org.junit.runner.RunWith;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.test.context.ContextConfiguration;
import org.springframework.test.context.junit4.SpringJUnit4ClassRunner;

@RunWith(SpringJUnit4ClassRunner.class)
@ContextConfiguration(locations = "classpath:spring-content.xml")
public class UserTest {

    @Autowired
    private UserService userService;

    @Test
    public void saveUserTest() {
        try {
            userService.doSomething();
        } catch (Exception e) {
            e.printStackTrace();
        }
    }
}

到此为止，代码已经贴完了。

那么，问题在哪儿呢？

在Service层，若是你仔细看，发如今service层saveUser方法上加了注解@Transactional，那么运行测试代码，不出意外（网络断了等）的状况下数据库里确定会插入一条数据。

假如，我把@Transactional这个注解去掉了，也就是说saveUser再也不使用spring的事务管理了，那么数据库里是否是没有插入数据呢？答案是否认的。数据库里依然会插入一条数据。

那这又是为何呢？

若是使用Spring进行事务管理，这里提交的时候是Spring的事务管理commit了事务。

在没有使用Spring管理的事务时，是没有使用Spring容器管理的SqlSession提交了事务。

==================================================

接下来，一个新的问题。

在saveUser方法上使用了@Transactional注解，代表这个方法是Spring容器管理的事务，那么我在userDAO.insert(user);以后抛出异常，那么插入的数据会回滚吗？

@Transactional
    @Override
    public boolean saveUser() throws Exception {

        User user = new User();
        user.setId(123l);
        user.setUsername("zhangsan");
        user.setPassword("123");
        user.setSalt("456");
        user.setSex("FEMAIL");
        user.setAddress("上海市张江高科");
        user.setCellphone("13582911229");
        user.setEmail("978732467@qq.com");
        user.setLock(false);
        user.setValidate(true);
        user.setDel(false);

        userDAO.insert(user);

        if (true) {
            throw new Exception("破坏性测试");
        }
        return true;
    }

答案是：不会回滚。

那怎样才会回滚呢？配置rollback便可。即：

@Transactional(rollbackFor = Exception.class)