Question

我想创建一个Android应用程序，用户可以在其中选择起点和终点，然后应用程序将计算到达目的地所需的距离和时间。

为了做到这一点，我使用谷歌方向网络服务。

以下是示例请求：

返回对象是json对象。

我不知道如何请求Web服务以及如何解析json对象。

提前谢谢。

Answer 1

//try this way
 String response = new JSONParser().getJSONFromUrl(makeURL(startLatitude,startLongitude,endLatitude,endtLongitude),new responseListener() {
        @Override
        public void onResponseComplete(String response) {
            try {
                ArrayList<HashMap<String, Object>> list = new ArrayList<HashMap<String, Object>>();
                JSONArray step = new JSONObject(response).getJSONArray("routes").getJSONObject(0).getJSONArray("legs")
                        .getJSONObject(0).getJSONArray("steps");

                for (int i = 0; i < step.length(); i++) {
                    HashMap<String,Object> row = new HashMap<String,Object>();
                    row.put("address", step.getJSONObject(i).getString("html_instructions"));
                    row.put("start",new LatLng(Double.parseDouble(step.getJSONObject(i).getJSONObject("start_location").getString("lat")), Double.parseDouble(step.getJSONObject(i).getJSONObject("start_location").getString("lng"))));
                    row.put("end",  new LatLng(Double.parseDouble(step.getJSONObject(i).getJSONObject("start_location").getString("lat")), Double.parseDouble(step.getJSONObject(i).getJSONObject("start_location").getString("lng"))));
                    list.add(row);

                }

            }catch (Exception e){
                e.printStackTrace();
            }
        }
    });
    public String makeURL(double startLatitude, double startLongitude, double endLatitude, double endLongitude) {
        StringBuilder localStringBuilder = new StringBuilder();
        localStringBuilder.append("http://maps.googleapis.com/maps/api/directions/json");
        localStringBuilder.append("?origin=");
        localStringBuilder.append(Double.toString(startLatitude));
        localStringBuilder.append(",");
        localStringBuilder.append(Double.toString(startLongitude));
        localStringBuilder.append("&destination=");
        localStringBuilder.append(Double.toString(endLatitude));
        localStringBuilder.append(",");
        localStringBuilder.append(Double.toString(endLongitude));
        localStringBuilder.append("&sensor=false&mode=driving&alternatives=true");
        return localStringBuilder.toString();
    }

    public class JSONParser {
        InputStream is = null;
        JSONObject jObj = null;
        String json = "";

        public JSONParser() {
        }

        public void getJSONFromUrl(final String url, final responseListener target) {
            new AsyncTask<Void, Void, String>() {
                protected String doInBackground(Void... params) {
                    HttpURLConnection httpURLConnection = null;
                    StringBuilder stringBuilder = new StringBuilder();
                    try {
                        httpURLConnection = (HttpURLConnection) new URL(url).openConnection();
                        InputStreamReader inputStreamReader = new InputStreamReader(httpURLConnection.getInputStream());

                        int read;
                        char[] buff = new char[1024];
                        while ((read = inputStreamReader.read(buff)) != -1) {
                            stringBuilder.append(buff, 0, read);
                        }
                        return stringBuilder.toString();
                    } catch (MalformedURLException localMalformedURLException) {
                        return "";
                    } catch (IOException localIOException) {
                        return "";
                    } finally {
                        if (httpURLConnection != null)
                            httpURLConnection.disconnect();
                    }
                }

                protected void onPostExecute(String result) {
                    super.onPostExecute(result);
                    target.onResponseComplete(result);
                }
            }.execute();
        }
    }

    interface responseListener{
        public void onResponseComplete(String response);
    }

Answer 2

您可以这样：

Better Explanation of JSON Parsing...

从谷歌方向Web服务解析json文件

2 个答案: