小粥学Mybatis(6)之新增数据的id返回值

DAO

/**
 * Description:用户的持久层接口
 * <p>
 * ClassName: IUserDAO
 * date: 2021/3/1 10:47
 *
 * @author Yin.Liu
 * @version 1.0
 * @since JDK 1.8
 */
public interface IUserDAO {
     /**
     * 保存用户
     * @param user
     */
    void saveUser(User user);
}

mapper.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">
<!--namespace必须是dao接口的全限定类名-->
<mapper namespace="xyz.zhouzhousag.dao.IUserDAO">
     <insert id="saveUser" parameterType="xyz.zhouzhousag.domain.User" >
        <!--配置插入操作后，返回插入数据的id-->
        <!--keyProperty:返回值的名称  order：AFTER代表插入后的行为  resultType：返回值类型-->
        <selectKey keyProperty="id" order="AFTER" resultType="Integer">
            select last_insert_id()
        </selectKey>
        insert into
            user(username,address,sex,birthday)
        values
            (#{username},#{address},#{sex},#{birthday})
    </insert>
</mapper>

测试类

/**
 *@ClassName MybatisTest
 *@Description TODO
 *@Author Yin.Liu8
 *@Date 2021/3/1 11:25
 *@Version 1.0
 */
public class MybatisTest {
    private InputStream in;
    private SqlSession sqlSession;
    private IUserDAO userDAO;

    @Before //用于测试方法之前使用
    public void init() throws Exception {
        //1.读取配置文件
        in = Resources.getResourceAsStream("SqlMapConfig.xml");
        //2.创建SqlSessionFactory工厂
        SqlSessionFactory factory = new SqlSessionFactoryBuilder().build(in);
        //3.使用工厂生产 SqlSession对象
        sqlSession = factory.openSession();
        //4.使用SqlSession创建DAO接口的代理对象
        userDAO = sqlSession.getMapper(IUserDAO.class);
    }


    @After   //用于测试方法之后
    public void destroy() throws Exception {
        //提交事务
        sqlSession.commit();
        //6.释放资源
        sqlSession.close();
        in.close();
    }
    
    @Test
    public void mybatisTest1(){
        User user = new User();
        user.setAddress("山西");
        user.setBirthday(new Date());
        user.setUsername("sag");
        user.setSex("男");

        System.out.println("保存之前：" + user.toString());

        userDAO.saveUser(user);

        System.out.println("保存之后：" + user.toString());
    }
    
}

结果展示

保存之前：User{id=null, username='sag', birthday=Mon Mar 01 22:04:43 CST 2021, sex='男', address='山西'}


保存之后：User{id=52, username='sag', birthday=Mon Mar 01 22:04:43 CST 2021, sex='男', address='山西'}