4.mybatis属性和表的列名不相同时的处理方法

/**
* 属性和表的列名不相同时的处理方法
* 1.sql中给列重新命名：
* 　　select tid id, tname name from teacher t where tid=#{id}
* 2.在teacherMapper.xml中使用resultMap标签
* 　　<select id="getTeacher2" parameterType="int" resultMap="getTeacherMap">
*　　　　select * from teacher where tid=#{id}
*　　</select>
*　　<resultMap type="Teacher" id="getTeacherMap">
*　　　　<id property="id" column="tid"/>
*　　　　<result property="name" column="tname"/>
*　　</resultMap>
* @author 魅力_小生
*
*/

mysql表：Teacher[tid, tname], Java 实体类：Teacher[id, name]

建表语句：

create table

CREATE TABLE `teacher` (

   `tid` int(11) NOT NULL auto_increment,

   `tname` varchar(20) default NULL,

   PRIMARY KEY  (`tid`)

 )

添加2条数据：
  1 老师A
  2 老师B

Teacher实体类：

public class Teacher {

    private int id;

    private String name;

    public Teacher() {

        super();

    }

    public Teacher(int id, String name) {

        super();

        this.id = id;

        this.name = name;

    }

    public int getId() {

        return id;

    }

    public void setId(int id) {

        this.id = id;

    }

    public String getName() {

        return name;

    }

    public void setName(String name) {

        this.name = name;

    }

    @Override

    public String toString() {

        return "Teacher [id=" + id + ", name=" + name + "]";

    }

}

一、第一种处理方法：sql中给列重新命名

select tid id, tname name from teacher t where tid=#{id}

1.1 写实体类关联的MapperXML：

<mapper namespace="com.mlxs.mybatis.test3.teacherMapper">

    <!--

     * 属性和表的列名不相同时的处理方法

      *         1.sql中给列重新命名：

      *             select tid id, tname name from teacher t where tid=#{id}

     -->

    <select id="getTeacher" parameterType="int" resultType="Teacher">

        select tid id, tname name from teacher t where tid=#{id}

    </select>

</mapper>

1.2 写java测试类

/**

     * 属性和表的列名不相同时的2种处理方法

     *         1.sql中给列重新命名：

     *             select tid id, tname name from teacher t where tid=#{id}

     * @author 魅力_小生

     *

     */

    @Test

    public void getTeacher(){

        //创建session，设置事务为true

        SqlSession session = MyBatisUtil.getSessionFactory().openSession(true);

        String statement = "com.mlxs.mybatis.test3.teacherMapper.getTeacher";

        Teacher teacher = session.selectOne(statement, "1");

        System.out.println("teacher--->"+teacher);

        session.close();

    }

1.3 结果

teacher--->Teacher [id=1, name=老师A]

二、第二种处理方法：使用resultMap标签

2.1 写实体类关联的MapperXML：

<mapper namespace="com.mlxs.mybatis.test3.teacherMapper">

    <!--

        属性和表的列名不相同时的处理方法:

        2.在teacherMapper.xml中使用resultMap标签

    -->

    <select id="getTeacher2" parameterType="int" resultMap="getTeacherMap">

        select * from teacher where tid=#{id}

    </select>

    <resultMap type="Teacher" id="getTeacherMap">

        <id property="id" column="tid"/>

        <result property="name" column="tname"/>

    </resultMap>

</mapper>

2.2 Java测试类

/**

     * 属性和表的列名不相同时的2种处理方法

     *         2.在teacherMapper.xml中使用resultMap标签

     *         <select id="getTeacher2" parameterType="int" resultMap="getTeacherMap">

     *            select * from teacher where tid=#{id}

     *        </select>

     *        <resultMap type="Teacher" id="getTeacherMap">

     *            <id property="id" column="tid"/>

     *            <result property="name" column="tname"/>

     *        </resultMap>

     * @author 魅力_小生

     *

     */

    @Test

    public void getTeacher2(){

        //创建session，设置事务为true

        SqlSession session = MyBatisUtil.getSessionFactory().openSession(true);

        String statement = "com.mlxs.mybatis.test3.teacherMapper.getTeacher2";

        Teacher teacher = session.selectOne(statement, "1");

        System.out.println("teacher--->"+teacher);

        session.close();

    }

2.3 结果

teacher--->Teacher [id=1, name=老师A]