android - 优雅地处理 AsyncTask 中的 IOException？

Question

当 AsyncTask 的 doInBackground 中发生 IOException 时，如何优雅地显示 Toast？

Answer 1

您可以覆盖 onPostExecute 或 onProgressUpdate 以在 UI 线程上显示消息。

要在扩展 AsyncTask 时使用 onProgressDisplay 将第二种类型声明为 String：

private class YourTask extends AsyncTask<ParamType, String, ReturnType> {

并覆盖 onProgressUpdate：

protected void onProgressUpdate(String... progress) {
     String errMsg = progress[0];
     Toast.makeText(getApplicationContext(), errMsg, Toast.LENGTH_SHORT).show();
}

那么你可以在doInBackground中发生异常时调用“progress”函数：

protected ReturnType doInBackground(ParamType... params) {
     try {
         // do stuff
     } catch (IOException e) {
        publishProgress("My Error Msg goes here");
     }
     return result;
 }

Answer 2

像这样：

Toast.makeText(Context context, int resId, int duration).show();

它需要一个上下文，所以只需将它传递给 AsyncTask。更多信息。

Answer 3

A dirty way is to create a different result in your IOException, for example if there is no internet connection you can check the connectivity in your IOException and set your result if connection exists to result='connection_to_server_issue' . If there is no connection result='no_connection'.

And later on on your postExecution you can check first your result if equals on of these two strings, and if so just execute a toastmessage, or whatever you want do do if one of these errors occurs.