Question

我必须制作一个项目，我需要计算从我的位置到目的地位置的距离，并在textview中显示它。请注意，当我的位置发生变化时，这个距离会更新。是否可以制作此类项目？

[注意：如果没有实施Google地图，我必须制作它。目的地lon，lat已知。只需找到我的位置并进行计算]

Answer 1

查看google android dev页面上的文档，了解如何监听位置更改。 http://developer.android.com/guide/topics/location/obtaining-user-location.html

您可以使用此功能确定当前（起点）点与目标点之间的距离。

 /**
 * 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

Location.distanceBetween将给出两点之间的直线距离。如果你想要两个地理点之间的PATH距离，那么你可以使用这个类来做到这一点：

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;


}

}

这将为您提供两点之间的路径/道路的距离或长度。

，这是解析JSON api的parser_Json类

 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;

     }

}

Answer 3

我在 this Question 中写下了两个不同的答案来计算两个地理点之间的差异，所以不要在这里复制粘贴，

第二件事也看到 this Example 与实施Locationlistener以获得onLocationChanged事件所需的方式相同。

在那个事件中，使用上面给出的函数计算差异并适当地使用它们。

Answer 4

使用LocationServices来确定您的位置并在每次收到更新时使用新距离更新TextView，这非常简单明了。

从我的位置到android中的目标位置的距离计算

4 个答案: