如何处理异步任务中的连接超时

Question

我有一个问题还没有解决，我需要帮助。

当网速慢时应用程序崩溃。如何在 asyntask 中检查连接超时。

我制作了一个有时会连接到 Web 服务以获取数据的应用程序，我使用异步任务来做到这一点

当用户可以选择是要重试还是取消时，我想在连接超时时发出警告对话框，如果他们选择重试，它将尝试重新连接

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

    InputStream ins;
    String status, result, s = null, data = "",js;
    int ss;
    int responseCode;

    @Override
    protected void onPreExecute() {
        super.onPreExecute();
        pdlg.setTitle("Checking");
        pdlg.setMessage("Please wait");
        pdlg.setCancelable(false);
        pdlg.show();
    }

    @Override
    protected Void doInBackground(Void... params) {
        StringBuilder sb = new StringBuilder();
        ArrayList al;
        try {
            URL url = new URL("http://....login.php");
            String param = "username=" + uname + "&password=" + pass;
            HttpURLConnection connection = (HttpURLConnection) url.openConnection();
            connection.setRequestMethod("POST");
            connection.setConnectTimeout(15000);
            connection.setReadTimeout(15000);
            connection.setDoInput(true);
            connection.setDoOutput(true);

            OutputStream os = connection.getOutputStream();
            BufferedWriter bw = new BufferedWriter(new OutputStreamWriter(os, "UTF-8"));
            bw.write(param);
            bw.flush();
            bw.close();

            responseCode = connection.getResponseCode();
            if (responseCode == HttpURLConnection.HTTP_OK) {
                BufferedReader br = new BufferedReader(new InputStreamReader(connection.getInputStream()));
                String line = "";
                while ((line = br.readLine()) != null) {
                    sb.append(line + "\n");
                }
            }
            data = sb.toString();
            JSONObject json = new JSONObject(data);

            status=json.getString("Status");//{"Login Status":"Success","Receipt Details":"No data available"}

           // js=json.getString("Login");//{"Login":"Failed"}



        } catch (MalformedURLException e) {
            Log.i("MalformedURLException", e.getMessage());
        } catch (IOException e) {
            Log.i("IOException", e.getMessage());
        } catch (JSONException e) {
            Log.i("JSONException", e.getMessage());
        }

        return null;
    }

    protected void onPostExecute(Void result) {
        super.onPostExecute(result);

        String status1=status.trim();


      if (status1.equals("Success")) {
    Toast.makeText(getApplicationContext(), "Login Succes  !!", Toast.LENGTH_SHORT).show();

          Intent i = new Intent(Login.this, Home.class);
          startActivity(i);
            finish();
          SharedPreferences sharedPreferences = PreferenceManager.getDefaultSharedPreferences(getApplicationContext());
          SharedPreferences.Editor editor = sharedPreferences.edit();
          editor.putBoolean("first_time", false);
          editor.putString("userrname", uname);
          editor.putString("password",pass);
          editor.apply();
          Toast.makeText(getApplicationContext(),"welcome : "+uname,Toast.LENGTH_LONG).show();

      }

else {
    Toast t=Toast.makeText(Login.this, "Username or Password is Incorrect", Toast.LENGTH_LONG);
          t.setGravity(Gravity.BOTTOM,0,0);
                        t.show();
}

        pdlg.dismiss();


    }



   }

Answer 1

使用这两个 catch 块来处理 ConnectionTimeOut 和 socketTimeOut 异常

        catch (SocketTimeoutException bug) {
            Toast.makeText(getApplicationContext(), "Socket Timeout", Toast.LENGTH_LONG).show();
        } 
        catch (ConnectTimeoutException bug) {
            Toast.makeText(getApplicationContext(), "Connection Timeout", Toast.LENGTH_LONG).show();
        }

Answer 2

对于连接超时，在您的 catch 块中添加 SocketTimeoutException 并且它会崩溃，因为没有空检查，您正在尝试 trim onPostExecute

中的字符串

你应该这样做，并在使用状态之前检查

if(TextUtil.isEmpty(status)) {
   pdlg.dismiss();
   // We are getting empty response
   return;
}
String status1=status.trim();

Answer 3

您尝试做的事情以前是在一些很棒的网络库中完成的。所以我强烈建议您使用 widley 使用的网络库之一。齐射.

或者如果你想了解你可以只检查响应状态（或者状态代码应该是 408。我猜是连接超时）如果它 return "connection time out" 那么你可以调用您的代码再次发送到 http 客户端以执行您的任务，您还可以添加重试计数以尝试 2-3 次然后放弃并将响应发送到 onpostexecute 方法。

希望对您有所帮助。

Answer 4

您可以在代码中捕获连接超时异常，然后根据您的要求设置状态，并在 onPostExecute 中检查该状态以显示警报对话框

try {
            URL url = new URL("http://....login.php");
            String param = "username=" + uname + "&password=" + pass;
    // Your URL connection code here
catch (ConnectTimeoutException e) {
        Log.e(TAG, "Timeout", e);
        status="timeout"
    } catch (SocketTimeoutException e) {
        Log.e(TAG, " Socket timeout", e);
        status="timeout"
    }

在onPostExecute

if (status.equals("timeout")) {
    // Show Alert Dialog.
}

Answer 5

您可以使用 getErrorStream() ,

HttpURLConnection connection = (HttpURLConnection) url.openConnection();
InputStream inp;

// if some error in connection 
 inp = connection.getErrorStream();

查看this答案了解更多详情..

根据doc吧returns

an error stream if any, null if there have been no errors, the connection is not connected or the server sent no useful data

.

如何处理异步任务中的连接超时

How to Handle connection timeout in async task

android

connection-timeout