MyBatis的dao层mapper配置

mapper.xml

<mapper namespace＝"所对应的接口">
  <sql id＝"sql1">sql语句起别名</sql>

  <select id＝"和接口中方法对应" parameterType＝"int" resultType＝"user">
  <include refid＝"sql1">或select语句
  </select>

  <select id＝"模糊查询" parameterType＝"String" parameterType＝"user">
  select * from user where username like '%${value}%'
 </select>

  //插入并返回主键
  <insert id＝"方法名" parameterType＝"user">
    <selectKey keyProperty＝"id" order＝"AFTER" resultType＝"int">
    select last_insert_id();
    </selectKey>
    insert into user(..) values(#{username}..)  
  </insert>

  update/delete同理
</mapper>

其余标签：

<where>
  <if test＝"username!＝null and sex!＝''">
  and username like '%${username}%'
  </if>
  <if>..
</where>

<foreach collection＝"ids//list变量名" item＝"id" open＝"id in (" close＝")" separator＝",">
#{id}
</foreach>

注意：占位符#{}和连接符${}区别
占位符自带''
连接符不带''用于like