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I'm writing an Android app and I need the ability to take a lat/long value and find the lat/long value of the nearest road to it. I've read the article at http://econym.org.uk/gmap/snap.htm, and tried to implement this, but I've had to use the Google Maps Webservices rather than javascript (since it's an android app). When I make a request like

maps.google.com/maps/api/directions/xml?origin=52.0,0&destination=52.0,0&sensor=true

it doesn't return me the closest road at all! Seems that the above method doesn't work with the webservices. Has anyone got any other ideas about how to solve this problem?

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1 回答 1

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您的 URL 似乎运行良好。

这是我用来测试它的 AsyncTask。

public class SnapToRoad extends AsyncTask<Void, Void, Void> {

private static final String TAG = SnapToRoad.class.getSimpleName();

@Override
protected Void doInBackground(Void... params) {
    Reader rd = null;
    try {
        URL url = new URL("http://maps.google.com/maps/api/directions/xml?origin=52.0,0&destination=52.0,0&sensor=true");
        HttpURLConnection con = (HttpURLConnection) url.openConnection();
        con.setReadTimeout(10000 /* milliseconds */);
        con.setConnectTimeout(15000 /* milliseconds */);
        con.connect();
        if (con.getResponseCode() == 200) {

            rd = new InputStreamReader(con.getInputStream());
            StringBuffer sb = new StringBuffer();
            final char[] buf = new char[1024];
            int read;
            while ((read = rd.read(buf)) > 0) {
                sb.append(buf, 0, read);
            }
            Log.v(TAG, sb.toString());
        } 
        con.disconnect();
    } catch (Exception e) {
        Log.e("foo", "bar", e);
    } finally {
        if (rd != null) {
            try {
                rd.close();
            } catch (IOException e) {
                Log.e(TAG, "", e);
            }
        }
    }
    return null;
}

在 logcat 输出中，如果您向下看几行，您应该会看到：

11-07 16:20:42.880: V/SnapToRoad(13920):     <start_location>
11-07 16:20:42.880: V/SnapToRoad(13920):      <lat>51.9999900</lat>
11-07 16:20:42.880: V/SnapToRoad(13920):      <lng>0.0064800</lng>
11-07 16:20:42.880: V/SnapToRoad(13920):     </start_location>

它们是您正在寻找的坐标。我希望这有帮助。

于 2011-11-07T22:35:15.140 回答