Teach you step by step how to view nearby people

The tutorial shared today is to teach you how to implement nearby people or other content. The server uses PHP. Before using it, please confirm whether your user data table stores the user's latest coordinates and update time. *** Create a separate table to store the user's latest coordinates and update time.

Before getting nearby people, you must first get your own coordinates. You can use baiduLocation to get the coordinates of the current user, and then use the current coordinates to request the server to return user data sorted by distance.

 apiready = function() {
    var baiduLocation = api.require( 'baiduLocation' );
    baiduLocation.startLocation({
 accuracy: '100m' ,
 filter: 1 ,
 autoStop: true  
 }, function(ret, err){
 var sta = ret.status;
        var lat = ret.latitude;
        var lon = ret.longitude;
 if (sta){
 //Successfully obtained  
 } else {
 //Get failed  
 }
 });
 };

//After successfully obtaining the location, the developer sends a request to the server

 api.ajax({
 url: request address,
 method: 'post' ,
 timeout: 30 ,
 dataType: 'json' ,
 returnAll: false ,
 data:{
        values: {lat: lat,lon:lon}
 }
 },function(ret,err){
 if (ret) {
        var urlJson = JSON.stringify(ret);
        api.alert({msg: urlJson});
 } else {
 api.alert({
 msg 'Error code:' +err.code+ '; Error message:' +err.msg+ 'Network status code:' +err.statusCode)
 });
 };
 });

In fact, the code on the APP side is very simple. It mainly obtains the coordinates and sends them to the server. The server then calculates the distance based on the transmitted coordinates and returns the data in order of distance. So the key point is how the server side implements

Let's take PHP as an example on the server side. First, get the data of the user with coordinates. This is foreach. Then calculate the distance based on the passed coordinates. The following is a piece of code in foreach

 Assume user data is $data;
 //Assemble the coordinates posted before foreach  
        $lat = $_POST[ 'lat' ];
        $lon = $_POST[ 'lon' ];
        $myLocation = $lon. ',' .$lat; 
 
    foreach($data as $key=>$v){
 //E: The coordinates of the other user are: 104.077638,30.673573  
    $v[ 'position' ] = "104.077638,30.673573" ;
      $newData[$key][ 'distance] = distanceBetween($myLocation,$v[' position']); 
 
 .......
 //Other user data  
 }

Then foreach the new array and sort it by distance

 foreach ($newData as $key => $r) {
        $distance[] = $r[ 'distance' ];
 } 
 
 array_multisort($distance, SORT_ASC, $newData);
 Output JSON array
 echo json_encode($newData);

Note: There is a custom function distanceBetween() in the foreach above;

This is used to calculate the distance between two coordinates. The code is as follows:

 /**
 * Calculate the distance between two coordinates (meters)
 * @param float $fP1Lat starting point (latitude)
 * @param float $fP1Lon starting point (longitude)
 * @param float $fP2Lat end point (latitude)
 * @param float $fP2Lon end point (longitude)
 * @return int
 */  
 function distanceBetween($mylonlat, $findlonlat){
        $mylonlat = explode( ',' , $mylonlat);
        $findlonlat = explode( ',' , $findlonlat);
        list($lng1,$lat1) = $mylonlat;
        list($lng2,$lat2) = $findlonlat;
        $EARTH_RADIUS= 6378.137 ;
 $PI= 3.1415926 ;
        $radLat1 = $lat1 * $PI / 180.0 ;
        $radLat2 = $lat2 * $PI / 180.0 ;
        $a = $radLat1 - $radLat2;
        $b = ($lng1 * $PI / 180.0 ) - ($lng2 * $PI / 180.0 );
        $s = 2 * asin(sqrt(pow(sin($a/ 2 ), 2 ) + cos($radLat1) * cos($radLat2) * pow(sin($b/ 2 ), 2 )));
        $s = $s * $EARTH_RADIUS;
        $s = round($s * 1000 );
 if ($len_type > 1 ) {
 $s /= 1000 ;
 }
        $distance = round($s/ 1000 , 2 );
 return $distance;
 }