MyBatis 延迟加载

在sqlMapConfig中进行设置

<configuration>

    <settings>

        <!--延迟加载的总开关-->

        <setting name="lazyLoadingEnabled" value="true"/>

        <!--设置为false才是启动延迟加载-->

        <setting name="aggresiveLazyLoading" value="false"/>

    </settings>

......

</configuration>

在mapper.xml中使用两次查询的方式；

 <!-- 2.查询两次select * from class where c_id = 1 ; SELECT * from teacher where

        t_id = 1 -->

    <select id="getClass2" resultMap="getClass2Map">

        select * from class where c_id

        =#{id}

    </select>

    <select id="getTeacher" parameterType="int" resultType="com.stone.bean.Teacher">

        select

        t_id id,t_name name

        from teacher where t_id=#{id}

    </select>

    <select id="getStudents" parameterType="int" resultType="com.stone.bean.Student">

        select

        S_id id,s_name name from student where c_id=#{id}

    </select>

    <resultMap type="com.stone.bean.ClassT" id="getClass2Map">

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

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

        <association property="teacher" column="t_id" select="getTeacher">

        </association>

        <collection property="list" column="c_id" select="getStudents"></collection>

    </resultMap>