Inner AlertDialog調用REST URL，我如何等待進度對話返回

Question

我有一系列在onclick方法中以菊花鏈方式連接的AlertDialog。在最後一個我需要發送一個URL調用並等待響應。一旦響應回來，我需要採取響應的消息並創建最後一個AlertDialog。問題是在2.3 Android中有效，但由於REST http調用在UI線程上運行，所以最新更改了Android 4.0錯誤。所以我想把它移到一個AsyncTask。我通讀了教程，但還沒有找到我的具體困境。這裏是我的代碼：我如何使AlertDialog等待響應，並等待顯示ProgressDialog或Spinner？我在尋找優雅的地方，AsyncTask是一個通用調用，可以在其他情況下用於REST調用。

public void onClick(View view) { 

    if(alert != null && alert.isShowing()) { 
     break; 
    } 

    alert = new AlertDialog.Builder(this) 
    .setTitle(getResources().getString(R.string.alertPingTitle1).toString()) 
    .setMessage(getResources().getString(R.string.alertPingMessage1).toString()) 
    .setPositiveButton(getResources().getString(R.string.alertPingPositive1).toString(), 
    new DialogInterface.OnClickListener() { 
     @Override 
     public void onClick(DialogInterface dialog, int which) { 
      if (onClicked) { 
       log.info("Preventing multiple clicks to Ping Node Id"); 
       return; 
      } 

      onClicked = true; 
      String returnMessage = ""; 
      int iconId = 0; 
      try { 
       String url = String.format(getResources().getString(R.string.urlIdPing).toString(), getRestUrl(), getId()); 

       // This is where the Rest call will happen in an AsyncTask 
       AsyncRest rest = new AsyncRest(Preferences.this); 
       rest.execute(new RestObject(type,null,null,true,false)); 

      .......................... 

       // This is the current state of the 2.3 code 
       JSONObject sent = RestRequest.sendPost(RestHttp.createHttpClient(), url, null, true); 
       if (sent != null && sent.getInt("response") == 200) { 
        returnMessage = "VALID REST call "; 
        iconId = android.R.drawable.ic_dialog_info; 
       } else { 
        if (sent != null) { 
         returnMessage = "INVALID REST response " + "\n\n Response code: " + sent.getInt("response"); 
        } else { 
         returnMessage = "INVALID REST call."; 
        } 
        iconId = android.R.drawable.ic_dialog_alert; 
       } 
      } catch(JSONException e) { 
       returnMessage = "Errored in JSON payload."; 
      } 

      alert = new AlertDialog.Builder(SetPreferences.this) 
      .setTitle(getResources().getString(R.string.alertPingTitle2).toString()) 
      .setMessage(returnMessage) 
      .setIcon(iconId) 
      .setPositiveButton(getResources().getString(R.string.alertOkay).toString(), 
      new DialogInterface.OnClickListener() { 
       @Override 
       public void onClick(DialogInterface dialog, int which) {} 
      }).show(); 

     } 
    }) 
}).show(); 

onClicked = false; 

} 

Answer 1

你並沒有真正具體地指定的問題是什麼，但我猜想那就是你不知道如何實現AsyncTask。

看一看的開發人員文件AsyncTask：http://developer.android.com/reference/android/os/AsyncTask.html

有，您可以按照有一個例子。基本上，你希望在AsyncTask的doInBackground()之內有你的REST調用。然後，在通話結束後對UI所做的任何更改都會在onPostExecute()之後進行。

編輯：詳細

private class AsyncRest extends AsyncTask<String, Void, Void> { 
    protected Void doInBackground(String... url) { 
    // do your REST call here 
    return null; 
    } 

    protected void onPostExecute(Void nothing) { 
    // update your UI here 
    } 
} 

要執行，請撥打new AsyncRest().execute(url);

要獲得的後臺任務的結果做出的get（）調用後執行。

AsyncRest rest = new AsyncRest(SetPreferences.this); 
rest.execute(new RestObject(Constants.ROTypes.post,url,null,null,true,false)); 
JSONObject sent = rest.get(); 

Answer 2

使用的AsyncTask您的代碼會是這個樣子：

在您的活動......

public MyActivity extends Activity implements AsyncRestCallback { 

    public void onClick(View view) { 

     if(alert != null && alert.isShowing()) { 
      break; 
     } 

     alert = new AlertDialog.Builder(this) 
     .setTitle(getResources().getString(R.string.alertPingTitle1).toString()) 
     .setMessage(getResources().getString(R.string.alertPingMessage1).toString()) 
     .setPositiveButton(getResources().getString(R.string.alertPingPositive1).toString(), 
     new DialogInterface.OnClickListener() { 
      @Override 
      public void onClick(DialogInterface dialog, int which) { 
       if (onClicked) { 
        log.info("Preventing multiple clicks to Ping Node Id"); 
        return; 
       } 

       onClicked = true; 
       String returnMessage = ""; 
       int iconId = 0; 
       String url = String.format(getResources().getString(R.string.urlIdPing).toString(), getRestUrl(), getId()); 

       AsyncRest rest = new AsyncRest().execute(url); 
      }) 
    }).show(); 

    onClicked = false; 

    } 

    @Override 
    public void finished(String returnMessage) { 

     alert = new AlertDialog.Builder(SetPreferences.this) 
     .setTitle(getResources().getString(R.string.alertPingTitle2).toString()) 
     .setMessage(returnMessage) 
     .setIcon(iconId) 
     .setPositiveButton(getResources().getString(R.string.alertOkay).toString(), 
     new DialogInterface.OnClickListener() { 
      @Override 
      public void onClick(DialogInterface dialog, int which) {} 
     }).show(); 
    } 
}  

RestAsync

public class AsyncRest extends AsyncTask<String, Integer, String> { 

    private AsyncRestCallback callback; 

    public AsyncRest(AsyncRestCallback callback) { 

     this.callback = callback; 
    } 

    @Override 
    protected String doInBackground(String... params) { 

     String returnMessage = ""; 
     String url = params[0] 

     try { 

      JSONObject sent = RestRequest.sendPost(RestHttp.createHttpClient(), url, null, true); 
      if (sent != null && sent.getInt("response") == 200) { 
       returnMessage = "VALID REST call "; 
       iconId = android.R.drawable.ic_dialog_info; 
      } 
      else { 
       if (sent != null) { 
        returnMessage = "INVALID REST response " + "\n\n Response code: " + sent.getInt("response"); 
       } 
       else { 
        returnMessage = "INVALID REST call."; 
       } 
       iconId = android.R.drawable.ic_dialog_alert; 
      } 
     } catch(JSONException e) { 
      returnMessage = "Errored in JSON payload."; 
     } 

     return returnMessage; 
    } 

    @Override 
    protected void onPostExecute(String returnMessage) { 

     callback.finished(returnMessage); 
    } 

    public interface AsyncRestCallback { 

     public void finished(String returnMessage); 
    } 
}