ibatis中传参$与#区别以及对List的排序

2012-12-17 posted in [遇到问题]

开发中ibatis会用到： $ 和 # 符号。

一、区别

$aaa$ 输出参数是以字符串方式直接输出 123
#aaa# 输出参数是以Parameter方式输出 @aaa

二、实例

SQL :

 <select id="selectMetaMandao"  parameterClass="java.util.HashMap" resultMap="WaasmetaMandaoMap" >  
     SELECT $subCategory$ rchannel,sum(mandao) mandao from
     ( SELECT nvl(channel,'-') channel,ROUND(count(1)*0.1131) mandao  FROM WAAS_VIEW_USER_RESULT a 
     AND not EXISTS (
     SELECT msgid
       FROM DT_XMS_MT b
      WHERE EXISTS
            (SELECT MSGID FROM WAAS_VIEW_USER_RESULT WHERE STATUS = 'SUCCESS' AND msgid = b.msgid)
     AND msgid = a.msgid)
        GROUP BY channel) d LEFT JOIN waas_channel_summary c ON d.channel = c.original_channel 
     <isNotEmpty property="channel">
             WHERE c.original_channel LIKE '%'||#channel#||'%' 
      </isNotEmpty>
        GROUP BY $subCategory$
 </select>

代码 :

 @RequestMapping("queryMeta.do")
 public void selectMeta(HttpServletRequest request, HttpServletResponse response) {
     String channel = request.getParameter("channel");
     Map<String, Object> param = new HashMap<String, Object>();
     //以参数方式输出, 相当于一个变量 (活的)
     param.put("channel", channel); 
     //以字符串方式输出, 直接输出(死的)
     param.put("subCategory", channel == null ? "primary_category" : "ORIGINAL_CHANNEL"); 
     List<WAASUserMOTypeResult> data = wumtService.selectMeta(param);
     //因为楼上这个List查完之后重新封装的, 所以无序, 要对List里面的对象进行排序, 如下
     Collections.sort(data, new Comparator<WAASUserMOTypeResult>() {
         public int compare(WAASUserMOTypeResult o1, WAASUserMOTypeResult o2) {
             return o2.getShijia() - o1.getShijia(); //排序字段, 倒序
         }
     });
		
     ......
		
     renderJson(response, resultJson.toString());

 }

实现效果:

如果传channel参数, 则根据原始媒体(ORIGINAL_CHANNEL)分组, 不传则根据合并后的大媒体(primary_category) 分组.

永久链接：https://dylanvivi.github.com/posts/ibatis-parameter.html