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"
    }
)