com.mongodb.DBCursor#count ( )源码实例Demo

/**
 * Calculates shard chunks.
 *
 * @param collection the collection
 * @return the deep partition [ ]
 */
private DeepPartition[] calculateShardChunks(DBCollection collection) {

    DBCursor chuncks = getChunks(collection);

    Map<String, String[]> shards = getShards(collection);

    MongoPartition[] deepPartitions = new MongoPartition[chuncks.count()];
    int i = 0;
    boolean keyAssigned = false;
    String key = null;
    while (chuncks.hasNext()) {

        DBObject dbObject = chuncks.next();
        if (!keyAssigned) {
            Set<String> keySet = ((DBObject) dbObject.get("min")).keySet();
            for (String s : keySet) {
                key = s;
                keyAssigned = true;
            }
        }
        deepPartitions[i] = new MongoPartition(mongoDeepJobConfig.getRddId(), i,
                new DeepTokenRange(shards.get(dbObject.get
                        ("shard")),
                        ((DBObject) dbObject.get
                                ("min")).get(key),
                        ((DBObject) dbObject.get("max")).get(key)), key);
        i++;
    }
    List<MongoPartition> mongoPartitions = Arrays.asList(deepPartitions);

    Collections.shuffle(mongoPartitions);
    return mongoPartitions.toArray(new MongoPartition[mongoPartitions.size()]);
}
 

/**
 * @see HttpServlet#doGet(HttpServletRequest request, HttpServletResponse
 *      response)
 * 
 *      Get resource
 */
protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {

	if (mDS != MongoService.getInstance()) {
		System.out.println("MongoService db name is changed");
		mDS = MongoService.getInstance();
		mCollRef = mDS.getCollection("refpoints");
		mCollSamp = mDS.getCollection("samplings");
		mCollMap = mDS.getCollection("maps");
	}
	
	String type = request.getParameter("type");
	String id = request.getParameter("id");
	System.out.println("doGet: type=" + type + " id=" + id);

	if ("file".equals(type)) {
		if (id == null) {
			// Get list of files
			mDS.sendJSON(mDS.getFileList(), request, response);
			return;
		}
		try {
			mDS.sendFile(id, response);
		} catch (Exception e) {
			System.err.println("Send error: " + id);
		}
		return;
	}

	// Get document(s)
	String distinct = request.getParameter("distinct");
	String pipeline = request.getParameter("pipeline");
	String query = request.getParameter("query");
	String keys = request.getParameter("keys");
	String format = request.getParameter("format");
	DBObject queryObj = query != null ? (DBObject) JSON.parse(query) : null;
	DBObject keysObj = keys != null ? (DBObject) JSON.parse(keys) : null;

	Object result = null;
	DBCollection collection = mDS.getCollection(type);
	if (id != null) {
		result = collection.findOne(new ObjectId(id), keysObj);
	} else if (distinct != null) {
		result = collection.distinct(distinct, queryObj);
	} else if (pipeline != null) {
		DBObject pipelineObj = (DBObject) JSON.parse(pipeline);
		if (pipelineObj instanceof List<?>) {
			result = collection.aggregate((List<DBObject>) pipelineObj).results();
		} else {
			result = collection.aggregate(pipelineObj).results();
		}
	} else {
		DBCursor cursor = collection.find(queryObj, keysObj);
		String sort = request.getParameter("sort");
		String skip = request.getParameter("skip");
		String limit = request.getParameter("limit");
		String count = request.getParameter("count");
		if (sort != null) {
			cursor = cursor.sort((DBObject) JSON.parse(sort));
		}
		if (skip != null) {
			cursor = cursor.skip(Integer.parseInt(skip));
		}
		if (limit != null) {
			cursor = cursor.limit(Integer.parseInt(limit));
		}
		result = "true".equals(count) ? cursor.count() : cursor;
	}
	if (id != null && result == null) {
		response.sendError(HttpServletResponse.SC_BAD_REQUEST, String.format("Document %s does not exist", id));
		return;
	}
	if ("csv".equals(format)) {
		mDS.sendCSV(result, request, response);
		return;
	}
	mDS.sendJSON(result, request, response);
}