Mongo批量查詢：MongoCursor

public Map<String,Map<Integer,JSONObject>> queryMessage(List ipId) {
        DBObject query1 = new BasicDBObject();
        BasicDBObject fieldObject = new BasicDBObject();
        fieldObject.put("themeCode",true);
        fieldObject.put("latest",true);
        fieldObject.put("message",true);
        fieldObject.put("ipId",true);
        query1.put(IPID,new BasicDBObject("$in", ipId));
        Query query2 = new BasicQuery(query1,fieldObject);
        DBCursor dbCursor =mongoJsdTemplate.getCollection("eagle_jsd_riskcon_third").find(query1);
        Map messageOneMap = Maps.newHashMap();
        Map messageTwoMap = Maps.newHashMap();

        while (dbCursor.hasNext()){
            DBObject object=dbCursor.next();
            String themeCode = Func.isEmpty(object.get("themeCode"))?"":object.get("themeCode").toString();
            Integer latest = Func.isEmpty(object.get("latest"))?1:Integer.valueOf(Func.isEmpty(object.get("latest"))?"":object.get("latest").toString());
            JSONObject message = Func.isEmpty(object.get("message"))?null:JSONObject.parseObject(object.get("message").toString());
            Integer ipIdd = Func.isEmpty(object.get("ipId"))?0:Integer.valueOf(Func.isEmpty(object.get("ipId"))?"":object.get("ipId").toString());

            if (Func.equals(themeCode,"RIM00135") && Func.equals(latest ,1)){
                if(Func.isNotEmpty(message)){
                    messageOneMap.put(ipIdd , message);
                }
            }
            if (Func.equals(themeCode,"RIM00136") && Func.equals(latest ,1)){
                if(Func.isNotEmpty(message)){
                    messageTwoMap.put(ipIdd , message);
                }
            }



        Map<String,Map<Integer,JSONObject>> returnMap = Maps.newHashMap();
        returnMap.put("RIM00135",messageOneMap);
        returnMap.put("RIM00136",messageTwoMap);
//        System.out.println("returnMap大小MessageOne" + returnMap.get("RIM00135").size());
//        System.out.println("returnMap大小MessageTwo" + returnMap.get("RIM00136").size());
        return returnMap;
    }
複製代碼

MongoCursor，他是mongo的遊標，他其實並無真正的查詢到結果，至關於懶加載，

在調用find時，MongoDB shell並不當即查詢數據庫，而是在等待真正開始獲取數據時才發送查詢。（相似Linq中IQueryable），你能夠經過遊標來對最終結果進行控制