从我的位置到目标位置的距离计算android

Question

我必须做一个项目，我需要计算从我的位置到目标位置的距离，并在textview中显示它。请注意，当我的位置更改时更新此距离。是否有可能制作这种类型的项目？

[注：不执行谷歌地图我必须做出后援目的地经度，纬度是known.Just必须找到我的位置，并计算]

Answer 1

查看google android dev页面上的文档，了解如何侦听位置变化。 http://developer.android.com/guide/topics/location/obtaining-user-location.html

您可以使用此功能来确定当前（开始）点和目标点之间的距离。

/** 
* using WSG84 
* using the Metric system 
*/ 
public static float getDistance(double startLati, double startLongi, double goalLati, double goalLongi){ 
    float[] resultArray = new float[99]; 
    Location.distanceBetween(startLati, startLongi, goalLati, goalLongi, resultArray); 
    return resultArray[0]; 
} 

Answer 2

这是非常简单的使用LocationServices确定您的位置并在每次收到更新时使用新的距离更新您的TextView。

Answer 3

我在这里2个不同的答案写下来this Question计算两个地理点之间的差异，从而不能复制，在此粘贴，

第二件事也看到this Example你需要以同样的方式执行Locationlistener即可获得onLocationChanged事件。

并在这种情况下使用上述给定函数计算差异并适当地使用它们。

Answer 4

Location.distanceBetween会给两点之间的直线距离。如果你想两个地理点之间PATH的距离，那么你可以使用通过使用此类做到这一点：

public class GetDistance { 

public String GetRoutDistane(double startLat, double startLong, double endLat, double endLong) 
{ 
    String Distance = "error"; 
    String Status = "error"; 
    try { 
     Log.e("Distance Link : ", "http://maps.googleapis.com/maps/api/directions/json?origin="+ startLat +","+ startLong +"&destination="+ endLat +","+ endLong +"&sensor=false"); 
     JSONObject jsonObj = parser_Json.getJSONfromURL("http://maps.googleapis.com/maps/api/directions/json?origin="+ startLat +","+ startLong +"&destination="+ endLat +","+ endLong +"&sensor=false"); 
     Status = jsonObj.getString("status"); 
     if(Status.equalsIgnoreCase("OK")) 
     { 
     JSONArray routes = jsonObj.getJSONArray("routes"); 
     JSONObject zero = routes.getJSONObject(0); 
     JSONArray legs = zero.getJSONArray("legs"); 
     JSONObject zero2 = legs.getJSONObject(0); 
     JSONObject dist = zero2.getJSONObject("distance"); 
     Distance = dist.getString("text"); 
     } 
     else 
     { 
      Distance = "Too Far"; 
     } 
    } catch (JSONException e) { 
     // TODO Auto-generated catch block 
     e.printStackTrace(); 
    } 
return Distance; 


} 

}

这会给两点之间的距离，你或路径/道路的长度。

这里是parser_Json类解析JSON API

public class parser_Json { 

public static JSONObject getJSONfromURL(String url){ 

    //initialize 
    InputStream is = null; 
    String result = ""; 
    JSONObject jArray = null; 

    //http post 
    try{ 
     HttpClient httpclient = new DefaultHttpClient(); 
     HttpPost httppost = new HttpPost(url); 
     HttpResponse response = httpclient.execute(httppost); 
     HttpEntity entity = response.getEntity(); 
     is = entity.getContent(); 

    }catch(Exception e){ 
     Log.e("log_tag", "Error in http connection "+e.toString()); 
    } 

    //convert response to string 
    try{ 
     BufferedReader reader = new BufferedReader(new InputStreamReader(is,"iso-8859-1"),8); 
     StringBuilder sb = new StringBuilder(); 
     String line = null; 
     while ((line = reader.readLine()) != null) { 
      sb.append(line + "\n"); 
     } 
     is.close(); 
     result=sb.toString(); 
    }catch(Exception e){ 
     Log.e("log_tag", "Error converting result "+e.toString()); 
    } 

    //try parse the string to a JSON object 
    try{ 
      jArray = new JSONObject(result); 
    }catch(JSONException e){ 
     Log.e("log_tag", "Error parsing data "+e.toString()); 
    } 

    return jArray; 
} 

public static InputStream retrieveStream(String url) { 

     DefaultHttpClient client = new DefaultHttpClient(); 

     HttpGet getRequest = new HttpGet(url); 

     try { 

      HttpResponse getResponse = client.execute(getRequest); 
      final int statusCode = getResponse.getStatusLine().getStatusCode(); 

      if (statusCode != HttpStatus.SC_OK) { 

       return null; 
      } 

      HttpEntity getResponseEntity = getResponse.getEntity(); 
      return getResponseEntity.getContent(); 

     } 
     catch (IOException e) { 
      getRequest.abort(); 

     } 

     return null; 

    } 

}