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将其显示在文本视图中。请注意，当我的位置更改时，此距离会更新。是否可以制作这种类型的项目？
[注意：没有实施谷歌地图，我必须制作它。目的地 lon ，lat 是已知的。只需找到我的位置并进行计算]
问问题
21124 次
4 回答
17
查看 google android dev 页面上的文档，了解如何监听位置变化。http://developer.android.com/guide/topics/location/obtaining-user-location.html
您可以使用此功能来确定当前（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];
}
于 2012-05-21T10:33:02.167 回答
12
Location.distanceBetween将给出两点之间的直线距离。如果您想要两个地理点之间的 PATH 距离，那么您可以使用此类：
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;
}
}
于 2012-05-25T06:43:54.067 回答
3
这非常简单，LocationServices可用于确定您的位置并TextView在每次收到更新时使用新距离更新您的位置。
于 2012-05-21T10:32:19.443 回答