mongodb 地理位置搜寻

LBS，存储每个地点的经纬度坐标，搜寻附近的地点，建立地理位置索引可提高查询效率。

mongodb地理位置索引，2d和2dsphere，对应平面和球面。

1.创建lbs集合存放地点坐标

 use lbs;

 db.lbs.insert(
     {
         loc:{
             type: "Point",
             coordinates: [113.332264, 23.156206]
         },
         name: "广州东站"
     }
 )

 db.lbs.insert(
     {
         loc:{
             type: "Point",
             coordinates: [113.330611, 23.147234]
         },
         name: "林和西"
     }
 )

 db.lbs.insert(
     {
         loc:{
             type: "Point",
             coordinates: [113.328095, 23.165376]
         },
         name: "天平架"
     }
 )

2.创建地理位置索引

 db.lbs.ensureIndex(
     {
         loc: "2dsphere"
     }
 )

3.查询附近的坐标

当前位置为：时代广场，

坐标：113.323568, 23.146436

搜寻附近一公里内的点，由近到远排序

 db.lbs.find(
     {
         loc: {
             $near:{
                 $geometry:{
                     type: "Point",
                     coordinates: [113.323568, 23.146436]
                 },
                 $maxDistance: 1000
             }
         }
     }
 )

搜寻结果：

 { "_id" : ObjectId("556a651996f1ac2add8928fa"), "loc" : { "type" : "Point", "coordinates" : [ 113.330611, 23.147234 ] }, "name" : "林和西" }

php代码如下：

 <?php
 // 连接mongodb
 function conn($dbhost, $dbname, $dbuser, $dbpasswd){
     $server = 'mongodb://'.$dbuser.':'.$dbpasswd.'@'.$dbhost.'/'.$dbname;
     try{
         $conn = new MongoClient($server);
         $db = $conn->selectDB($dbname);
     } catch (MongoException $e){
         throw new ErrorException('Unable to connect to db server. Error:' . $e->getMessage(), 31);
     }
     return $db;
 }

 // 插入坐标到mongodb
 function add($dbconn, $tablename, $longitude, $latitude, $name){
     $index = array('loc'=>'2dsphere');
     $data = array(
             'loc' => array(
                     'type' => 'Point',
                     'coordinates' => array(doubleval($longitude), doubleval($latitude))
             ),
             'name' => $name
     );
     $coll = $dbconn->selectCollection($tablename);
     $coll->ensureIndex($index);
     $result = $coll->insert($data, array('w' => true));
     return (isset($result['ok']) && !empty($result['ok'])) ? true : false;
 }

 // 搜寻附近的坐标
 function query($dbconn, $tablename, $longitude, $latitude, $maxdistance, $limit=10){
     $param = array(
         'loc' => array(
             '$nearSphere' => array(
                 '$geometry' => array(
                     'type' => 'Point',
                     'coordinates' => array(doubleval($longitude), doubleval($latitude)),
                 ),
                 '$maxDistance' => $maxdistance*1000
             )
         )
     );

     $coll = $dbconn->selectCollection($tablename);
     $cursor = $coll->find($param);
     $cursor = $cursor->limit($limit);

     $result = array();
     foreach($cursor as $v){
         $result[] = $v;
     }

     return $result;
 }

 $db = conn('localhost','lbs','root','123456');

 // 随机插入100条坐标纪录
 for($i=0; $i<100; $i++){
     $longitude = '113.3'.mt_rand(10000, 99999);
     $latitude = '23.15'.mt_rand(1000, 9999);
     $name = 'name'.mt_rand(10000,99999);
     add($db, 'lbs', $longitude, $latitude, $name);
 }

 // 搜寻一公里内的点
 $longitude = 113.323568;
 $latitude = 23.146436;
 $maxdistance = 1;
 $result = query($db, 'lbs', $longitude, $latitude, $maxdistance);
 print_r($result);
 ?>

演示php代码，首先需要在mongodb的lbs中创建用户和执行auth。方法如下：

 use lbs;
 db.createUser(
     {
         "user":"root",
         "pwd":"123456",
         "roles":[]
     }
 )

 db.auth(
     {
         "user":"root",
         "pwd":"123456"
     }
 )