mybatis关联映射

多对一：

 <!--    方法一： -->
     <select id="getNewsListByPage" parameterType="com.zqc.share.model.news.NewsPage" resultMap="newsPageMap">
       select * from news limit #{newsPage.page},#{newsPage.size}
     </select>

  <resultMap id="newsPageMap" type="com.zqc.share.model.news.NewsPage">
          <id column="id" property="id"/>
          <result column="description" property="description"/>
          <result column="title" property="title"/>
          <result column="head_image" property="head_image"/>
          <result column="publishtime" property="publishtime"/>
          <result column="readtimes" property="readtimes"/>
          <result column="goodcount" property="goodcount"/>
          <result column="badcount" property="badcount"/>
          <association property="user" column="user_id" javaType="com.zqc.share.model.user.User"  select="com.zqc.share.dao.user.UserDao.getUserById" />
          <association property="topic" column="topic_id" javaType="com.zqc.share.model.topic.Topic"  select="com.zqc.share.dao.topic.TopicDao.getTopicById" />
     </resultMap>

 <select id="getTopicById" parameterType="int" resultType="com.zqc.share.model.topic.Topic">
          select * from topic where id=#{topic_id}
     </select>

 <select id="getUserById" parameterType="int" resultType="com.zqc.share.model.user.User">
          select * from user where id=#{user_id}
     </select>

<!-- 方法2 -->

<select id="getNewsListByPage" parameterType="com.zqc.share.model.news.NewsPage" resultMap="newsPageMap">
        select * from user u,news n,topic t where n.user_id=u.id and n.topic_id=t.id limit #{newsPage.page},#{newsPage.size}
    </select>

    <resultMap type="com.zqc.share.model.news.NewsPage"  id="newsPageMap">
        <id column="id" property="id"/>
        <result column="description" property="description"/>
        <result column="title" property="title"/>
        <result column="topic_id" property="topic_id"/>
        <result column="user_id" property="user_id"/>
        <result column="head_image" property="head_image"/>
        <result column="publishtime" property="publishtime"/>
        <result column="readtimes" property="readtimes"/>
        <result column="goodcount" property="goodcount"/>
        <result column="badcount" property="badcount"/>
        <association property="user" javaType="com.zqc.share.model.user.User"  resultMap="userMap" />
       <association property="topic" javaType="com.zqc.share.model.topic.Topic"  resultMap="topicMap" /> 

    </resultMap>

    <resultMap type="com.zqc.share.model.user.User"  id="userMap">
          <id column="id" property="id"/>
          <result column="name" property="name"/>
          <result column="head_image" property="head_image"/>
          <result column="mobile" property="mobile"/>
          <result column="email" property="email"/>
          <result column="address" property="address"/>
          <result column="age" property="age"/>
          <result column="user_no" property="user_no"/>
          <result column="password" property="password"/>
    </resultMap>

    <resultMap type="com.zqc.share.model.topic.Topic"  id="topicMap">
          <id column="id" property="id"/>
          <result column="name" property="name"/>
          <result column="description" property="description"/>
    </resultMap>

一对多+多对一：

 <select id="getNewsById" parameterType="com.zqc.share.model.news.News" resultMap="newsMap">
          select n.id,n.description,n.title,n.head_image,n.publishtime,n.readtimes,n.goodcount,n.badcount,n.topic_id,n.user_id,
             i.image,i.context,i.news_id,i.id
             from news_item i,news n,topic t,user u
             where i.news_id=n.id and n.id = #{news.id}
     </select>

 <resultMap id="newsMap" type="com.zqc.share.model.news.News">
          <id column="id" property="id"/>
          <result column="description" property="description"/>
          <result column="title" property="title"/>
          <result column="head_image" property="head_image"/>
          <result column="publishtime" property="publishtime"/>
          <result column="readtimes" property="readtimes"/>
          <result column="goodcount" property="goodcount"/>
          <result column="badcount" property="badcount"/>
          <association property="user" column="user_id" javaType="com.zqc.share.model.user.User"  select="com.zqc.share.dao.user.UserDao.getUserById" />
          <association property="topic" column="topic_id" javaType="com.zqc.share.model.topic.Topic"  select="com.zqc.share.dao.topic.TopicDao.getTopicById" />
          <collection property="newsItems" ofType="com.zqc.share.model.news.NewsItem" resultMap="newsItemsMap"/>
     </resultMap>

     <resultMap type="com.zqc.share.model.news.NewsItem"  id="newsItemsMap">
           <result column="id" property="id"/>
           <result column="news_id" property="news_id"/>
           <result column="image" property="image"/>
           <result column="context" property="context"/>
     </resultMap>

 <select id="getTopicById" parameterType="int" resultType="com.zqc.share.model.topic.Topic">
          select * from topic where id=#{topic_id}
     </select>

 <select id="getUserById" parameterType="int" resultType="com.zqc.share.model.user.User">
          select * from user where id=#{user_id}
     </select>