Shulou(Shulou.com)06/01 Report--

I don't use mongoDB very much. I remember using a little when I was a "parent assistant". It's just that when I was doing the "dispatch system" last year, I used mongoDB again.

Here first a brief introduction to the dispatch system, dispatch system in the cloud pedicure (O2O, door-to-door pedicure) in charge of order delivery, improve the efficiency of order completion of a system. Mainly when one comes, it will quickly find the most suitable and best technician and return it to the user according to the service item, service time and service place of the order. Due to the requirements of the door-to-door pedicure special industry, it is not possible to assign a technician to the order directly. Instead, some of the excellent technicians selected are returned to the user, leaving the user to choose which technician to assign.

After the background of the project is finished, it is the question of the choice of technical solutions. At first, I wanted to store the longitude and latitude of technicians based on HBase, a distributed, column-oriented open source database. Then stream the location of the technician through storm. Later, it felt that HBase was too heavy and not easy to maintain. At the same time, it also takes into account a problem that small companies will face-the problem of cost. This kind of plan was abandoned. Then, I want to choose a non-relational database to store the data, and then I think of Mongodb. All right, this is the data layer. Distributed architecture we use Ali's dubbo. I won't say much about the reasons for choosing it. First of all, it is widely used in the market. In the future, its characteristics will be described in detail. Distributed control uses zookeeper and cross-system middleware uses ActiveMq. This is still a brief explanation of why you choose this, instead of choosing RocketMq, which is more commonly used in the market. One of the most important reasons is that it has been used in previous work, and the application scenario of MQ is to report longitude and latitude at the master end, the reliability of the message is not very high, and the learning cost is reduced. At this point, I feel that I have said too much, and today I am mainly talking about the application of mongodb.

Next, let's write an implementation of geographic retrieval based on mongodb.

Controller layer

/ / query nearby @ ResponseBody@RequestMapping (value = "/ geoNearN", method = RequestMethod.GET, produces = {"application/json;charset=UTF-8"}) public String testQueryMongoTopN () {CarPointNearQuery personQuery = new CarPointNearQuery (); Random random = new Random (); double [] arr = MongoUtil.getRandomLocation (); / / check up to 100 records personQuery.setCount (100); / / Random 1km meters to 10km int distance = random.nextInt (10); personQuery.setDistance (distance) PersonQuery.setLongitude (arr [0]); personQuery.setLatitude (arr [1]); return JSON.toJSONString (mongoLbsService.geoNearCarPoint (personQuery));}

Service layer

Public CarPointNearResult geoNearCarPoint (CarPointNearQuery carPointNearQuery) {CarPointNearResult carPointNearResult = new CarPointNearResult (); if (carPointNearQuery! = null & & carPointNearQuery.getLongitude ()! = 0.0D & & carPointNearQuery.getLatitude ()! = 0.0D) {Point point = new Point (carPointNearQuery.getLongitude (), carPointNearQuery.getLatitude ()); NearQuery near = NearQuery.near (point, Metrics.KILOMETERS); Query query = new Query () / / quantity query.limit (carPointNearQuery.getCount () = = 0?100:carPointNearQuery.getCount ()); near.query (query); / / distance near.maxDistance (new Distance (carPointNearQuery.getDistance () = = 0.0D?1.0D:carPointNearQuery.getDistance (), Metrics.KILOMETERS)); near.spherical (true) / / call the DAO layer to get the data GeoResults geoResults = this.carPointDao.geoNear (near, CarPoint.class, "carPoint"); carPointNearQuery.setCount (geoResults.getContent (). Size ()); carPointNearQuery.setDistance (near.getMaxDistance (). GetValue ()); carPointNearResult.setCarPointNearQuery (carPointNearQuery); List geoResultsContent = geoResults.getContent (); ArrayList resultsList = new ArrayList (); Iterator i$ = geoResultsContent.iterator () While (i$.hasNext ()) {GeoResult geoResult = (GeoResult) i$.next (); CarPointResult carPointResult = new CarPointResult (); carPointResult.setDistance (geoResult.getDistance (). GetValue ()); carPointResult.setCarPoint ((CarPoint) geoResult.getContent ()); resultsList.add (carPointResult);} carPointNearResult.setCarPointList (resultsList); return carPointNearResult } else {logger.error ("geoNear parameter exception"); carPointNearResult.setErrorCode (ErrorCode.PARAM_ERROR); return null;}}

DAO layer

Public GeoResults geoNear (NearQuery near, Class clazz, String collectionName) {/ / use mongoTemplate directly GeoResults geoResults = this.mongoTemplate.geoNear (near, clazz, collectionName); return geoResults;}

The above is the use of mongodbTemplate to achieve geographic retrieval functions, there are many ways about mongodb geographic retrieval, you can refer to the mongodb Chinese community, which has a specific introduction.

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