Mybatis如何按顺序查询出对应的数据字段

mybatis按顺序查询出对应的数据字段

今天遇到一个问题，就是写xml文件时，返回的顺序始终不一致，无论我sql语句写的如何好，前端接收到的数据都是乱的。终于，我发现到了原因。

原来我的查询返回resulttype = "map"  ， 也就是这个map, 打乱了顺序。

因为map 并不保证存入取出顺序一致, 因此，打乱顺序可想而知了。

解决方法

resulttype = "map" 改为  resulttype="java.util.linkedhashmap" 。

介绍：返回为linkedhashmap时，表中存储的null值并不会存入map中。

mybatis基本查询、条件查询、查询排序

<?xml version="1.0" encoding="utf-8"?>
<!doctype mapper public "-//mybatis.org//dtd mapper 3.0//en"
        "http://mybatis.org/dtd/mybatis-3-mapper.dtd">
<mapper namespace="com.inspur.analysis.tool.ontology.linktype.dao.linktypemapper">
    <resultmap type="com.inspur.analysis.tool.ontology.linktype.data.linktype" id="linktype">
        <id property="linkuri" column="link_uri"/>
        <result property="urihash" column="uri_hash"/>
        <result property="basetypeuri" column="base_type_uri"/>
        <result property="linklabel" column="link_label"/>
        <result property="isasymmetrical" column="is_asymmetrical"/>
        <result property="aliase" column="aliase"/>
        <result property="pcname" column="p_c_name"/>
        <result property="pcaliase" column="p_c_aliase"/>
        <result property="cpname" column="c_p_name"/>
        <result property="cpaliase" column="c_p_aliase"/>
        <result property="detailiconuri" column="detail_icon_uri"/>
        <result property="detailicon" column="detail_icon"/>
        <result property="edgeiconuri" column="edge_icon_uri"/>
        <result property="edgeicon" column="edge_icon"/>
        <result property="issys" column="is_sys"/>
        <result property="note" column="note"/>
        <result property="creatorid" column="creator_id"/>
        <result property="createtime" column="create_time"/>
        <result property="editorid" column="editor_id"/>
        <result property="edittime" column="edit_time"/>
        <result property="scn" column="scn"/>
    </resultmap>
    <select id="existlinktypeuri" parametertype="string"
            resultmap="linktype">
        select * from od_link_type
        where link_uri = #{linkuri}
    </select>
    <select id="isrootlinktype" parametertype="string"
            resulttype="int">
        select exists(select link_uri from od_link_type
                                      where link_uri=base_type_uri and link_uri=#{linkuri})
    </select>
    <select id="deleterootlinktype" parametertype="string">
        delete from od_link_type where base_type_uri=#{basetypeuri}
    </select>
    <select id="getrootlinktypelist"  resultmap="linktype">
        select * from od_link_type
        where link_uri =  base_type_uri
    </select>
    <select id="getalllinktypelistbyparent" parametertype="java.util.map"
            resultmap="linktype">
        select * from od_link_type
        <where>
            link_uri != base_type_uri
            <if test="basetypeuri != null">
              and base_type_uri=#{basetypeuri}
            </if>
        </where>
        <if test="orderfield != null" >
         order by 
           <choose>    
                <when test="orderfield == 'linkuri'">    
                    link_uri ${orderdir} 
                </when>  
                 <when test="orderfield == 'linklabel'">    
                    link_label ${orderdir} 
                </when>  
                 <otherwise>
                   base_type_uri ${orderdir}
                </otherwise> 
            </choose>    
        </if>
    </select>
    <select id="getlinktypelistbycondition" parametertype="java.util.map"  resultmap="linktype">
        select * from od_link_type
        <where>
            link_uri != base_type_uri
            <if test="linkuri != null">
               and link_uri like '%${linkuri}%'
            </if>
            <if test="linklabel != null">
                and link_label like '%${linklabel}%'
            </if>
            <if test="basetypeuri != null">
                and base_type_uri=#{basetypeuri}
            </if>
        </where>
      <if test="orderfield != null" >
         order by 
           <choose>    
                <when test="orderfield == 'linkuri'">    
                    link_uri ${orderdir} 
                </when>  
                 <when test="orderfield == 'linklabel'">    
                    link_label ${orderdir} 
                </when>  
                 <otherwise>
                   base_type_uri ${orderdir}
                </otherwise> 
            </choose>    
        </if>
    </select>
</mapper>

以上为个人经验，希望能给大家一个参考，也希望大家多多支持。