android - 应用程序在 Android 中的 SocketTimeoutException 上崩溃

Question

我已经在 Activity 中正确地实现了 AsyncTask(基于许多来源)。

我还调查了 SocketTimeoutException 并捕获了异常，您可以在下面的代码中看到。

无论如何，当我停止 webapi 并模拟 SocketTimeoutException 时，应用会立即崩溃。 (请检查错误消息。)

调试代码转到 IOException，然后我看到错误消息并重新启动应用。

代码

private class FetchHauls extends AsyncTask<String, Void, String> {

        @Override
        protected String doInBackground(String... params) {
            HttpURLConnection urlConnection = null;
            BufferedReader reader = null;

            try {
                AppSettings.ComplexPreferences complexPreferences = AppSettings.ComplexPreferences.getComplexPreferences(context, "App_Settings", 0);
                AppSettings appSettings = complexPreferences.getObject("App_Settings", AppSettings.class);
                if (appSettings != null) {
                    String uri = appSettings.getIpAddress() + "/api/Version1/GetGrandTotalStats";

                    GrandTotalStatsRequest grandTotalStatsRequest = new GrandTotalStatsRequest();
                    Date d = new Date();
                    CharSequence timeOfRequest = DateFormat.format("yyyy-MM-dd HH:mm:ss", d.getTime()); 
                    grandTotalStatsRequest.AtTime = timeOfRequest.toString();
                    grandTotalStatsRequest.DeviceID = appSettings.getDeviceID();

                    grandTotalStatsRequest.DeviceSerialNumber = appSettings.getSerialNumber();

                    Gson gson = new Gson();
                    String json = gson.toJson(grandTotalStatsRequest);

                    //Connect
                    urlConnection = (HttpURLConnection) ((new URL(uri).openConnection()));
                    urlConnection.setDoOutput(true);
                    urlConnection.setRequestProperty("Content-Type", "application/json");
                    urlConnection.setRequestProperty("Accept", "application/json");
                    urlConnection.setRequestMethod("POST");
                    urlConnection.setConnectTimeout(60000);
                    urlConnection.setReadTimeout(55000);
                    urlConnection.connect();

                    //Write
                    OutputStream outputStream = urlConnection.getOutputStream();
                    BufferedWriter writer = new BufferedWriter(new OutputStreamWriter(outputStream, "UTF-8"));
                    writer.write(json);
                    writer.close();
                    outputStream.close();

                    String result = null;
                    //Read
                    InputStream inputStream = urlConnection.getInputStream();
                    if (inputStream != null) {
                        BufferedReader bufferedReader = new BufferedReader(new InputStreamReader(inputStream, "UTF-8"));

                        String l = null;
                        StringBuilder sb = new StringBuilder();

                        while ((l = bufferedReader.readLine()) != null) {
                            sb.append(l);
                        }

                        bufferedReader.close();

                        result = sb.toString();
                    }

                    return result;
                }
            } catch (IOException e) {
            } catch (Exception e) {
            } finally {
                if (urlConnection != null) {
                    urlConnection.disconnect();
                }
                if (reader != null) {
                    try {
                        reader.close();
                    } catch (final IOException ex) {
                    }
                }
            }

            return null;
        }

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

            if (isCancelled()) {
                return;
            }

            swiperefresh.setRefreshing(false);
            taskFetchHauls = null;
            if (TextUtils.isEmpty(s)) return;

            try {
                // Some code...

            } catch (Exception ex) {
                Log.e(PAGE_TITLE, ex.getMessage());
            }
        }
    }

}

错误

java.net.SocketTimeoutException: failed to connect to /172.15.15.2 (port 1067) after 60000ms
                        at libcore.io.IoBridge.connectErrno(IoBridge.java:169)
                        at libcore.io.IoBridge.connect(IoBridge.java:122)
                        at java.net.PlainSocketImpl.connect(PlainSocketImpl.java:183)
                        at java.net.PlainSocketImpl.connect(PlainSocketImpl.java:452)
                        at java.net.Socket.connect(Socket.java:884)
                        at com.android.okhttp.internal.Platform.connectSocket(Platform.java:117)
                        at com.android.okhttp.internal.http.SocketConnector.connectRawSocket(SocketConnector.java:160)
                        at com.android.okhttp.internal.http.SocketConnector.connectCleartext(SocketConnector.java:67)
                        at com.android.okhttp.Connection.connect(Connection.java:152)
                        at com.android.okhttp.Connection.connectAndSetOwner(Connection.java:185)
                        at com.android.okhttp.OkHttpClient$1.connectAndSetOwner(OkHttpClient.java:128)
                        at com.android.okhttp.internal.http.HttpEngine.nextConnection(HttpEngine.java:341)
                        at com.android.okhttp.internal.http.HttpEngine.connect(HttpEngine.java:330)
                        at com.android.okhttp.internal.http.HttpEngine.sendRequest(HttpEngine.java:248)
                        at com.android.okhttp.internal.huc.HttpURLConnectionImpl.execute(HttpURLConnectionImpl.java:433)
                        at com.android.okhttp.internal.huc.HttpURLConnectionImpl.connect(HttpURLConnectionImpl.java:114)
                        at android.apps.ktk.company.gpsmegatracker.Activities.GrandStatActivity$FetchHauls.doInBackground(GrandStatActivity.java:291)
                        at android.apps.ktk.company.gpsmegatracker.Activities.GrandStatActivity$FetchHauls.doInBackground(GrandStatActivity.java:259)
                        at android.os.AsyncTask$2.call(AsyncTask.java:295)
                        at java.util.concurrent.FutureTask.run(FutureTask.java:237)
                        at android.os.AsyncTask$SerialExecutor$1.run(AsyncTask.java:234)
                        at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1113)
                        at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:588)
                        at java.lang.Thread.run(Thread.java:818)
Disconnected from the target VM, address: 'localhost:8617', transport: 'socket'

Answer 1

如果你想捕获一个SocketTimeoutException，那么你应该使用下面的模式。请仔细注意，我们捕获从大多数特定到大多数一般的异常。因为 SocketTimeoutException 是 IOException 的子类，所以我们先捕获前者。使用相反的顺序将导致您看到的错误。最后，我们最后捕获一般的 Exception。

@Override
protected String doInBackground(String... params) {
    HttpURLConnection urlConnection = null;
    BufferedReader reader = null;

    try {
        // make the async call

    }
    catch (SocketTimeoutException se) {
        // display timeout alert to user
    }
    catch (IOException e) {
        // handle general IO error
    }
    catch (Exception e) {
        // just in case you missed anything else
    }
    finally {
        if (urlConnection != null) {
            urlConnection.disconnect();
        }
        if (reader != null) {
            try {
                reader.close();
            } catch (final IOException ex) {
            }
        }
    }
}