mongodb分组排序

	@Override
	public MessageDto getCheckInMembersByFlight(String fltDt, String fltNr, String channel,String origincd,String destcd) {
		log.info("请求参数："+"fltDt:"+fltDt+",fltNr:"+fltNr+",channel:"+channel+",origincd:"+origincd+",destcd:"+destcd);
		MessageDto messageDto = new MessageDto();
		boolean flag = (null !=fltDt&&!("").equals(fltDt)
				&&null !=fltNr&&!("").equals(fltNr)
				&&null !=channel&&!("").equals(channel)
				&&null !=origincd&&!("").equals(origincd)
				&&null !=destcd&&!("").equals(destcd))
				&&(channel.equals("WX")|channel.equals("APP"));
		if (flag) {
			String fltDtStr = fltDt.replace("-","")+"000000";
			//分组的依据psgId
			DBObject keys = new BasicDBObject("psgId", true);
			//dbObject为检索条件，检索出符合业务的数据
			BasicDBObject dbObject = new BasicDBObject();
			dbObject.put("fltDt", fltDtStr);
			String fltNrSub = fltNr.substring(2);
			dbObject.put("fltNr", fltNrSub);
			dbObject.put("checkinStatus", "AC");
			dbObject.put("originCd", origincd);
			dbObject.put("destCd",destcd );
			//设定下面函数的初始值：prev的字段dcsTimestamp的初始值，用于做比较取dcsTimestamp的最大值
			DBObject initial = new BasicDBObject("dcsTimestamp", "0");
			//这个属于js的语法，这个脚本用于在psgId组内，比较出较大的dcsTimestamp，并且取出这条数据中要返回的值
			//注意后面的赋值要有dcsTimestamp的赋值，不然得出的数据不准确
			String reduce = "function(doc,prev){" +
					"var docDcsTimestamp=doc.dcsTimestamp;" +
					"var prevDcsTimestamp=prev.dcsTimestamp;" +
					"var docDcsTimestampInt=parseInt(docDcsTimestamp);" +
					"var prevDcsTimestampInt=parseInt(prevDcsTimestamp);" +
					"if(docDcsTimestampInt > prevDcsTimestampInt){" +
					"prev.fqNo=doc.fqNo;" +
					"prev.credentNo=doc.credentNo;" +
					"prev.chnName=doc.chnName;prev.dcsTimestamp=doc.dcsTimestamp;}" +
					"}";
			BasicDBList dbList = (BasicDBList) mongoTemplate.getCollection("b_dep_pnr_psg").group(keys, dbObject, initial, reduce);
			log.info("分组处理成功");
			JSONArray resultJson = new JSONArray();
			for (int i = 0; i < dbList.size(); i++) {
				//取出最终的得到数据中的要返回的参数，封装到map转json返回。添加name和证件号不为空判断，其中一个为空不返回
				JSONObject jsStr = JSONObject.parseObject(dbList.get(i).toString());
				String fqNoStr = (String) jsStr.get("fqNo");
				String chnName = (String) jsStr.get("chnName");
				String credentNo = (String) jsStr.get("credentNo");
				Map<String, String> map = new HashMap<String, String>();
				ObjectMapper mapJson = new ObjectMapper();
				if(null!=chnName&&!chnName.equals("")&&null!=credentNo&&!credentNo.equals("")){
					map.put("fqNo", fqNoStr);
					map.put("name", chnName);
					map.put("credentNo", credentNo);
				}else{
					continue;
				}
				String params = null;
				JSONObject resultJsonObiect = null;
				try {
					params = mapJson.writeValueAsString(map);
					resultJsonObiect = JSONObject.parseObject(params);
				} catch (JsonProcessingException e) {
					e.printStackTrace();
				}
				resultJson.add(resultJsonObiect);
			}
			messageDto.setMessage("成功");
			messageDto.setCode("0");
			messageDto.setContent(resultJson);
		} else {
			messageDto.setMessage("参数个数不对");
			messageDto.setCode("10001");
			messageDto.setContent(null);
		}

		return messageDto;
	}

　　2、分组也可，

public void query1(){ 
          String mondburl = Config.getInstance().getProperty("mongodb.host");
          MongoClientOptions options = new MongoClientOptions.Builder().socketKeepAlive(true).build();
          Mongo  client = new MongoClient(mondburl,  options);
          DB database = client.getDB("pnr");
          DBCollection coll = database.getCollection("b_dep_pnr_flt");
          
//条件
          DBObject dbObject = new BasicDBObject();
        dbObject.put("alnCd",  "CZ"); 
        dbObject.put("fltNr",  "3452"); 
        dbObject.put("fltDt",  "20180425000000"); 
        dbObject.put("arvCd",  "SZX");
        dbObject.put("depCd",  "LJG"); 
          //FindIterable<Document> dbCursor = col.find((Bson) dbObject);
        /*创建 $match, 作用相当于query*/
         DBObject match = new BasicDBObject("$match", dbObject);
         
         /* Group操作*/
         DBObject groupFields = new BasicDBObject("_id",null);
         groupFields.put("MAXDcsTimestamp", new BasicDBObject("$max", "$dcsTimestamp"));
         DBObject group = new BasicDBObject("$group", groupFields);
         
         /* 查看Group结果 */
         AggregationOutput output = coll.aggregate(match, group); // 执行 aggregation命令
         Iterable<DBObject> results = output.results();
         
         for (DBObject dbObject2 : results) {
             System.out.println(dbObject2.toString());
        }
         
        }