方法一：

/** 业务逻辑 */

BasicDBObject query=new BasicDBObject();

query.put("state", "3");

JSONArray jsonarray=dao.getGroupCountWhere(query, "yl_dormitory");

for(int i=0;i<jsonarray.size();i++){

JSONObject jsob=jsonarray.getJSONObject(i);

String ment_id=jsob.getString("ment_id");

String count=jsob.getString("count");

//JSONArray jarment = dao.find(new BasicDBObject("_id", new ObjectId(ment_id)), "ment");

//JSONObject jsoba = jarapartment.getJSONObject(0);

//count=jsoba.get("count").toString();

dao.update(new BasicDBObject("_id",new ObjectId(ment_id)),

new BasicDBObject("count",String.valueOf(count))

.append("update_time", System.currentTimeMillis() / 1000),"ment");

}

 

/**

* 加条件的聚合统计

* @param doc

* @param collection

* @return

*/

public JSONArray getGroupCountWhere(BasicDBObject basicOB, String collection){

List<DBObject> list = new ArrayList<DBObject>();

JSONArray appendDor_userJar = new JSONArray();

try{

db = mg.getDB(DATABASENAME);

// 条件

DBObject match = new BasicDBObject("$match", basicOB);

// 利用$project拼装group需要的数据

DBObject fields = new BasicDBObject("ment_id", 1);

fields.put("_id", 1);

DBObject project = new BasicDBObject("$project", fields);

BasicDBObject groupFilters = new BasicDBObject("_id", "$ment_id");

groupFilters.put("count", new BasicDBObject("$sum", 1));

// 利用$group进行分组

BasicDBObject group = new BasicDBObject("$group", groupFilters);

// 按_id（即day）升序排列

DBObject sort = new BasicDBObject("$sort", new BasicDBObject("_id", 1));

// 取前N条数据 并计算没条数据的

// DBObject limit = new BasicDBObject("$limit", n);

List<DBObject> pipeline = Arrays.asList(match, project, group, sort);

AggregationOutput output = db.getCollection(collection)

.aggregate(pipeline);

// 计算

Iterable<DBObject> it = output.results();

Iterator<DBObject> itor = it.iterator();

while (itor.hasNext()) {

DBObject map=itor.next();

JSONObject appendDor_userJsob = new JSONObject();

if(null!=map.get("_id") && !map.get("_id").equals("")){

appendDor_userJsob.put("count",map.get("count"));

appendDor_userJsob.put("id",map.get("_id"));

appendDor_userJar.add(appendDorJsob);

}

System.out.println("count:"+map.get("count")+":"+map.get("_id"));

}

}catch(Exception e){

e.printStackTrace();

}finally{

if(db!=null){

db=null;

}

}

return appendDor_userJar;

}

 

 

 

 

方法二：

 /** 业务逻辑 */

  Document group = new Document();

  Document groupData = new Document();

  groupData.append("_id", "$apartment_id");

  groupData.append("dormitory_count", new BasicDBObject("$sum", 1));

  group.append("$group", groupData);

  MongoDBDao dao = MongoDBDao.getMongoDBDaoInstance();

  List<Document> list = dao.getGroupCount(group, "yl_dormitory");

  JSONArray jsonarray=JSONArray.fromObject(list);

 

 

 

/**

* 聚合统计

* @param doc

* @param collection

* @return

*/

public List<Document> getGroupCount(Document doc, String collection){

MongoDatabase database = mg.getDatabase(DATABASENAME);

MongoCollection<Document> coll = database.getCollection(collection);

List<Bson> groups = new ArrayList<Bson>();

groups.add(doc);

MongoCursor<Document> cursor = coll.aggregate(groups).iterator();

List<Document> list = new ArrayList<Document>();

while (cursor.hasNext()) {

list.add(cursor.next());

}

return list;

}