MyBitis(iBitis)系列随笔之三：简单实现CRUD

 

Mybitis(iBitis)实现对对象增删改查操作要借助<select/>查询，<insert/>增加，<update/>更新，<delete/>删除 标签来操作。

值得注意的有两点：
  1、在对对象进行增删改时，SqlSession session = sqlSessionFactory.openSession();获取的session。必选执行session.commit();否则操作无效。
  2、Mybitis与hibernate一样，插入数据后会把id值赋值给缓存中对象

还是接着上一讲的代码继续改动
UserMapper.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="user">
     <resultMap id="userResultMap" type="user">
        <id property="id" column="id"/>
        <result property="userName" column="name"/>
        <result property="password" column="pass"/>
     </resultMap>

    <!--resultType 表示com.jefry.User这样一个实体对象 -->
    <select id="selectUser" parameterType="int"  resultMap="userResultMap" >
        select * from t_user where id = #{id}
    </select>

    <!--增加操作-->
    <insert id="addUser" parameterType="user"
            useGeneratedKeys="true" keyProperty="id">
            insert into t_user(name,pass) values(#{userName},#{password})
    </insert>

    <!--更新操作-->
    <update id="modifyUser" parameterType="user">
         update t_user set name=#{userName}, pass=#{password} where id=#{id}
    </update>

    <delete id="deleteUser" parameterType="int">
       delete from t_user where id=#{id}
    </delete>

</mapper>

测试代码

public class Test {
    static String resource = "mybatis-config.xml";

    public static void main(String[] args) throws IOException {
        // TODO Auto-generated method stub
        InputStream inputStream = Resources.getResourceAsStream(resource);
        SqlSessionFactory sqlSessionFactory = new SqlSessionFactoryBuilder().build(inputStream);
        SqlSession session = sqlSessionFactory.openSession();
        try {
            //User.selectUser中User对应UserMapper.xml文件中标签<mapper namespace="User"> namespace的值
            //selectUser 对应UserMapper.xml文件中标签<select id="selectUser" parameterType="int" resultType="com.jefry.User">中id值
            User user = session.selectOne("user.selectUser", 1);
            System.out.println("user.getName()=" +  user.getPassword());

            User addUser = new User();
            addUser.setUserName("NEWWWWW");
            addUser.setPassword("111111");
            session.insert("user.addUser", addUser);

            //插入操作
            User modifyUser = new User();
            modifyUser.setUserName("NEWWWWW");
            modifyUser.setPassword("111111");
            modifyUser.setId(1);

            //修改用户
            session.update("user.modifyUser", addUser);

            //删除操作
            session.delete("user.deleteUser",2);

            //这里必须commit,否则增删改无效
            session.commit();

            //与hibernate一样，插入数据后会把id值赋值给缓存中的id
            System.out.println("addUser.getId()" + addUser.getId() );

        } finally {
            session.close();
        }
    }

}