try {  
			ServerAddress serverAddress = new ServerAddress("localhost", 27017);  
			List<ServerAddress> addrs = new ArrayList<ServerAddress>();  
			addrs.add(serverAddress);  
			MongoCredential credential = MongoCredential.createScramSha1Credential("admin", "admin","admin".toCharArray());  
			List<MongoCredential> credentials = new ArrayList<MongoCredential>();  
			credentials.add(credential);  
			//通过连接认证获取MongoDB连接  
			MongoClient mongoClient = new MongoClient(addrs,credentials);  
			//连接到数据库  
			db = mongoClient.getDatabase("test");
			MongoCollection<Document> collection = db.getCollection("aa");
		} catch (Exception e) {  
			System.err.println( e.getClass().getName() + ": " + e.getMessage() );  
		}

//条件查询并去重
public static List<String> query2(MongoCollection<Document> collection,long beginDay,long endDay) {  
		//db.routedata.distinct(('lanmac'),{"time":{$gte:1464624000000,$lte:1464659580000}})
		List<String> list = new ArrayList<String>();
		Document query = new Document();
		query.put("time", new BasicDBObject("$gte",beginDay).append("$lte",endDay));
		MongoCursor<String> li = collection.distinct("lanmac",query,String.class ).iterator();
		while (li.hasNext()) {
			String n = li.next();
			list.add(n);
		}  
		return list;  
	}