未从 OpenWeatherMap api android studio 接收任何数据

Question

我不知道问题到底出在哪里，只要我登录到来自 api 的信息，应用程序就会崩溃。 这是代码。我不知道代码是否过时，我正在运行最新版本的 Android Studio。

public class DownloadTask extends AsyncTask<String, Void, String> {

    @Override
    protected String doInBackground(String... urls) {

        String result = "";
        URL url;
        HttpURLConnection urlConnection = null;

        try {
            url = new URL(urls[0]);

            urlConnection = (HttpURLConnection) url.openConnection();

            InputStream in = urlConnection.getInputStream();

            InputStreamReader reader = new InputStreamReader(in);

            int data = reader.read();

            while (data != -1) {

                char current = (char) data;

                result += current;

                data = reader.read();

            }

            return result;

        } catch (MalformedURLException e) {
            e.printStackTrace();
        } catch (IOException e) {
            e.printStackTrace();
        }

        return null;
    }

    @Override
    protected void onPostExecute(String result) {
        super.onPostExecute(result);

        try {

            JSONObject jsonObject = new JSONObject(result);

            String weatherInfo = jsonObject.getString("weather");

            Log.i("Weather content", weatherInfo);

            JSONArray arr = new JSONArray(weatherInfo);

            for (int i = 0; i < arr.length(); i++) {

                JSONObject jsonPart = arr.getJSONObject(i);

                Log.i("main", jsonPart.getString("main"));
                Log.i("description", jsonPart.getString("description"));

            }


        } catch (JSONException e) {
            e.printStackTrace();
        }



    }
}

如果你能帮助我，那就太棒了，我很高兴能制作自己的天气应用程序！

Answer 1

您不会像这样转换单个字节并转换为字符：

char current = (char) data;

您的result 字符串最终会包含很多奇怪的字符

您将InputStreamReader 包装成BufferedReader，逐行读取并收集您的JSON。

另一种更简单的方法是使用JSONObject 来读取您的信息流：

JSONParser jsonParser = new JSONParser();
JSONObject jsonObject = (JSONObject)jsonParser.parse(
          new InputStreamReader(urlConnection.getInputStream(), "UTF-8"));

然后把你的AsyncTask改成直接返回JSONObject

public class DownloadTask extends AsyncTask<String, Void, JSONObject> {

    @Override
    protected String doInBackground(String... urls) {

        String result = "";
        URL url;
        HttpURLConnection urlConnection = null;

        try {
            url = new URL(urls[0]);

            urlConnection = (HttpURLConnection) url.openConnection();

            InputStream in = urlConnection.getInputStream();

            InputStreamReader reader = new InputStreamReader(in, "UTF-8");
            JSONParser jsonParser = new JSONParser();
            return (JSONObject)jsonParser.parse(reader);;

        } catch (MalformedURLException e) {
            e.printStackTrace();
        } catch (IOException e) {
            e.printStackTrace();
        }

        return null;
    }
    @Override
    protected void onPostExecute(JSONObject result) {
    }
}