myBatis association和collection用法实例

Xml代码：

<resultMap id="BaseResultMap" type="com.yc.pojo.Crouse">    <id column="crouse_id" property="crouseId" jdbcType="BIGINT"/>    <result column="title" property="title" jdbcType="VARCHAR"/>    <result column="crouse_code" property="crouseCode" jdbcType="VARCHAR"/>    <result column="user_id" property="userId" jdbcType="BIGINT"/>    <result column="max_persons" property="maxPersons" jdbcType="INTEGER"/>    <result column="price" property="price" jdbcType="DECIMAL"/>    <result column="crouse_all_times" property="crouseAllTimes" jdbcType="INTEGER"/>    <result column="create_time" property="createTime" jdbcType="VARCHAR"/>    <result column="state" property="state" jdbcType="INTEGER"/><association property="students" javaType="com.yc.pojo.CrouseStudent"> <!--association用于数组 -->    <result column="s_id" property="id"            jdbcType="BIGINT"/>    <result column="s_user_id" property="userId"            jdbcType="BIGINT"/>    <result column="s_notes" property="notes"            jdbcType="VARCHAR"/>    <result column="s_state" property="state"            jdbcType="INTEGER"/>    <result column="s_user_status" property="userStatus"            jdbcType="INTEGER"/></association><collection column="user_id" property="user" ofType="com.yc.pojo.User"> <!--collection用于对象  -->    <result column="u_email" property="email"            jdbcType="VARCHAR"/>    <result column="u_name" property="name"            jdbcType="VARCHAR"/>    <result column="u_head_img" property="headImg"            jdbcType="VARCHAR"/>    <result column="u_tel" property="tel"            jdbcType="VARCHAR"/>    <result column="u_wx_number" property="wxNumber"            jdbcType="VARCHAR"/>    <result column="u_sex" property="sex"            jdbcType="VARCHAR"/>    <result column="u_create_time" property="createTime"            jdbcType="VARCHAR"/></collection></resultMap>

<select id="selectByQuery" resultMap="BaseResultMap" parameterType="com.yc.query.CrouseQuery">        SELECT        c.*, u.user_id AS u_user_id,        u.email AS u_email,        u.name as u_name,        u.head_img as u_head_img,        u.tel AS u_tel,        u.wx_number AS u_wx_number,        u.sex AS u_sex,        s.id AS s_id,        s.user_id AS s_user_id,        s.notes AS s_notes,        s.state AS s_state,        s.state AS s_state,        s.user_status AS s_user_status        FROM        crouse c        LEFT JOIN user u ON u.user_id = c.user_id        LEFT JOIN crouse_details d ON d.crouse_id = c.crouse_id        LEFT JOIN crouse_code cc ON c.crouse_id = cc.code_id        LEFT JOIN crouse_img i ON cc. CODE = c.crouse_code        LEFT JOIN rating r on r.crouse_id=c.crouse_id        LEFT JOIN crouse_student s on s.crouse_id=c.crouse_id        <where>            c.crouse_id is not null            <if test="crouseCode != null">                and c.crouseCode LIKE CONCAT('%', CONCAT(#{crouseCode}, '%'))            </if>            <if test="minPrice != null">                and c.price >= #{minPrice}            </if>            <if test="maxPrice != null">                and c.price < #{minPrice}            </if>            <if test="maxPersons != null">                and c.max_persons <= #{maxPersons}            </if>            <if test="minTimes != null">                and c.price >= #{minPrice}            </if>            <if test="maxTimes != null">                and c.price < #{maxTimes}            </if>            <if test="crouceState == null">                and d.state =1            </if>            <if test="address == null">                and d.address is not null            </if>            <if test="startTime == null">                and d.address is not null            </if>        </where> </select>