Google 距离矩阵没有得到距离

Question

我已经粗略地尝试从 Google Distance Matrix API 解析 JSON，但它没有显示距离。

我的 GPS 位置不是我确定的 0,0。

String distance = getMatrix(latitude,longitude);

我的函数代码是：

private String getMatrix(double lat , double lang){
  JSONObject jObj;
  String getdistance = "";
  String strUrl = "http://maps.googleapis.com/maps/api/distancematrix/json?origins=" 
                  + Double.toString(my_lat) + "," 
                  + Double.toString(my_lang) 
                  + "&destinations="+ Double.toString(lat) + "," 
                  + Double.toString(lang) 
                  + "&mode=walking&sensor=false";

  String data = "";
  InputStream reader = null;
  HttpURLConnection urlConnection = null;
  try{
    URL url = new URL(strUrl);
    urlConnection = (HttpURLConnection) url.openConnection();
    urlConnection.connect();

    reader = urlConnection.getInputStream();
    int bRead = -1;
    byte[] buffer = new byte[1024];
    do {
      bRead = reader.read(buffer, 0, 1024);
      if (bRead == -1) {
        break;
      }
      data += new String(buffer, 0, bRead);
    } while (true);
    urlConnection.disconnect();
  } catch(Exception e) {
  } finally {

  }

  try {
    jObj = new JSONObject(data);

    JSONArray rowsArray = jObj.getJSONArray("rows");
    JSONObject rows = rowsArray.getJSONObject(0);

    JSONArray elementsArray = rows.getJSONArray("elements");
    JSONObject newDisTimeOb = elementsArray.getJSONObject(0);

    JSONObject distOb = newDisTimeOb.getJSONObject("distance");
    getdistance = distOb.optString("text").toString();
  } catch (JSONException e) {
    e.printStackTrace();
  }

  return getdistance;
}

Answer 1

首先，检查您是否在代码中正确构建了 url 字符串：

String strUrl = "http://maps.googleapis.com/maps/api/distancematrix/json?origins=" 
                  + Double.toString(my_lat) + "," 
                  + Double.toString(my_lang) 
                  + "&destinations="+ Double.toString(lat) + "," 
                  + Double.toString(lang) 
                  + "&mode=walking&sensor=false";

// Line to check if url code is right
Log.d("APP", "strUrl = " + strUrl);

然后检查你下面的代码，是否真的产生了数据：

reader = urlConnection.getInputStream();
int bRead = -1;
byte[] buffer = new byte[1024];
do {
  bRead = reader.read(buffer, 0, 1024);
  if (bRead == -1) {
    break;
  }
  data += new String(buffer, 0, bRead);
} while (true);

我的建议是使用 BufferedReader 而不是逐字节读取响应字节。

然后更改：

getdistance = distOb.optString("text").toString();

到

getdistance = distOb.getString("text");

因为这里不需要再转成字符串

我搜索过 Client Libraries for Google Maps Web Services and found DistanceMatrixApi.java。也许我们可以使用它，但我不能保证。

Google 距离矩阵没有得到距离

Google Distance Matrix not getting distance

java

android

json

parsing

google-distancematrix-api