Question

我通过调用简单的选择查询来接收JSON格式的值。我正在使用AsyncTask。问题是它有时候工作正常，但有时response_value为空而没有任何变化。我该怎么办？我错过了什么？

代码 doInBackground(String... strings)

URL url = new URL(GetUrl.URL_MAIN_CATEGORIES_DATA);
                HttpURLConnection httpURLConnection = (HttpURLConnection) url.openConnection();
                httpURLConnection.setRequestMethod("POST");
                httpURLConnection.setDoInput(true);
                httpURLConnection.setDoOutput(true);

                InputStream inputStream = httpURLConnection.getInputStream();
                BufferedReader bufferedReader = new BufferedReader(new InputStreamReader(inputStream, "iso-8859-1"));
                String response_value = "";
                String line = "";
                while ((line = bufferedReader.readLine()) != null) {
                    response_value += line;
                }
                bufferedReader.close();
                inputStream.close();
                httpURLConnection.disconnect();
                return response_value;

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

Answer 1

尝试在catch块中记录异常，而不是打印堆栈跟踪。

Log.e("Yourtag","Exception occurred",e);

你必须得到一个异常，但你无法在android上看到堆栈跟踪。这是它有时可以工作的唯一方式，有时则不会。

有时在AsyncTask中返回值为null

1 个答案: