Question

我在AsyncTask doInBackground中有回调。我想在回调完成后更新UI。我的问题是我无法返回我的回调响应，所以我不知道如何做到这一点。基本上，我想将myString从我的回调响应返回到onPostExecute。

 $url = "https://hidden-for-privacy-and-security-reasons";

$optional_headers = array("authorization: something valid is here","cache-control: no-cache", "content-type: application/json");

  $params['http']['header'] = $optional_headers;

  $context = stream_context_create($params);

  $fpointer = fopen($url, 'r', false, $context);

  if($fpointer !== false)
  {
      $resphdrs = stream_get_meta_data($fpointer);
      if ($resphdrs["wrapper_data"][0] == "HTTP/1.1 201 Created")
      {
       error_log("SUCCESSFULLY received = " .$resphdrs["wrapper_data"][0], 0);
      }
      else
      {
       header($resphdrs["wrapper_data"][0]);
       error_log("Some ERROR occurred= " .$resphdrs["wrapper_data"][0], 0);
      }
   }
  else 
  {
      header("HTTP/1.1 500 Internal Server Error");
      error_log("500 error received", 0);
     // echo $get_error_header[0];
  }

Answer 1

1- override是一种您AsyncTask<Param, Progress, Result>无法创建的方法。

2-将extends class更改为此//AsyncTask<Param, Progress, Result> private class PotatoAsyncTask extends AsyncTask<Object, Void, String> { private static String passedString; PotatoAsyncTask() { } @Override protected void onPreExecute() { super.onPreExecute(); // In the UI thread // before calling doInBackground() } @Override protected String doInBackground(Object... params) { // In another thread than the UI thread // do what you want here Util.syncMessages(token, new Util.OnSyncMessages() { @Override public void onSyncMessages(boolean success, String myString) { if (success) { passedString = myString; return; // this is not the return of doInBackground } } }); return returnString;// return what you want in here } @Override protected void onPostExecute(String returnString) { super.onPostExecute(returnString); // In UI thread // after doInBackground is completely done } @Override protected void onCancelled(String returnString) { super.onCancelled(returnString); // in case the doInBackground was cancelled at one point but there is still a result } @Override protected void onCancelled() { super.onCancelled(); // } }，请参阅下面的示例

{{1}}

Answer 2

似乎很难在内部类中返回值，希望这会有所帮助：

 private class MyAsyncTask extends AsyncTask<Object, String, Void> {

    MyAsyncTask() {

    }

    @Override
    protected void doInBackground(Object... params) {

            Util.syncMessages(token, new Util.OnSyncMessages() {
                @Override
                public void onSyncMessages(boolean success, String myString) {
                    if (success) {
                        //return myString; // can't return here
                        publishProgress(myString);
                    }
                }
            });
    }

     @Override
    protected void onProgressUpdate(String... values) {
        super.onProgressUpdate(values);
        String str = values[0];
        //do something with str in main Thread.

    }



}

在AsyncTask doInBackground中回调后更新UI

2 个答案: