Question

我想在后台同步我的应用程序...并使用基于通知的方法。我有一个广播接收器，服务，活动和另一个带有Receiver的Context参考的java类。收到推送通知后...接收方呼叫服务，服务调用BackgroundSync。 BackgroundSync类执行一些齐射网络调用，并且成功时，它将数据存储在异步任务内的本地数据库中。现在在这个类的onPostExecute（）中..我想在activity上调用一个方法来显示一个对话框。

//Inside service. This method is called from receiver on receiving push notification

public static void syncDataFromServer(Context context) {
  Toast.makeText(context, "Data Sync Started", Toast.LENGTH_LONG).show();
  try {
    new BackgroundSync(context);
    Log.d("SYNC", "Called BackgroundSync Class with Context " + context);
  } catch (Exception e) {
    Log.d("SYNC", "Exception BackgroundSync Class :" + e.toString());
  }
}

这是后台同步类：

public class BackgroundSync implements IRequestCallback {

    private Context context;

    BackgroundSync(Context context) {
    this.context = context;
    fetchRetailers(context);
    }

    private class InsertTask extends AsyncTask<String, Void, String> {
    @Override
    protected String doInBackground(String... params) {
    try {
    DBAdapter dbAdapter = new DBAdapter(context);
    dbAdapter.open();
    dbAdapter.insertData(params[0], false);
    dbAdapter.close();
    Log.d("SYNC", "Retailers saved to Local database in Async Task of BackgroundSync");
    } catch (IllegalAccessException e) {
    Log.d("SYNC", "Exception "+e.toString());
    }
    return "";
    }

    @Override
    protected void onPostExecute(String s) {
    super.onPostExecute(s);
    MainActivity.notifyBackgroundSyncDone(context);
    }
    }

    @Override
    public void fetchRetailerResponseAPI(Object response, String str) {
    try {
    new InsertTask().execute(response.toString());
    Log.d("SYNC", "Fetch Retailer API Success");
    } catch (Exception e) {
    Log.d("SYNC", "Exception "+e.toString());
    }
    }
    }


    public void fetchRetailers(Context context) {
    try {
    BaseData baseData = new BaseData();
    baseData.setApi(Constants.VIEW_RETAILERS_API);
    baseData.setUrl(CommonUtil.getBaseUrl() + "distributors/" + Integer.parseInt(Prefs.getId(context)) + "/retailers");
    baseData.setPostOrGet(Request.Method.GET);
    Task task = new Task(this, context);
    task.getData(baseData);
    Log.d("SYNC", "Fetching retailers from Server");
    } catch (Exception e) {
    Log.d("SYNC", "Exception "+e.toString());
    }
    }
}

一切都运作良好......我能够在我的活动中展示祝酒......但是我无法展示对话。看起来各种情况都存在一些问题。

这是活动中的方法：

 public static void notifyBackgroundSyncDone(Context context){
        Toast.makeText(context, "Data Sync Finished", Toast.LENGTH_LONG).show();

        AlertDialog.Builder builder1 = new AlertDialog.Builder(context);
        builder1.setMessage("Write your message here.");
        builder1.setCancelable(true);
        builder1.setPositiveButton("Yes",
                new DialogInterface.OnClickListener() {
                    public void onClick(DialogInterface dialog, int id) {
                        dialog.cancel();
                    }
                });
        builder1.setNegativeButton("No",
                new DialogInterface.OnClickListener() {
                    public void onClick(DialogInterface dialog, int id) {
                        dialog.cancel();
                    }
                });

        AlertDialog alert11 = builder1.create();
        alert11.show();

    }

Answer 1

AlertDialog，因此他们的Builder需要Activity Context来绘制与GUI相关的设置和资源。您在Context中传递的BroadcastReceiver是Application Context，其中没有必要的资源，会导致AlertDialog创建失败。

如果您希望直接从AlertDialog或Service展示与BroadcastReceiver非常相似的内容，则可以使用{{1}创建Activity }主题，并以Dialog开头，并附加任何必要的数据作为附加内容。

Answer 2

执行此操作并尝试显示您的对话框

public static void notifyBackgroundSyncDone(Context context){
        Toast.makeText(context, "Data Sync Finished", Toast.LENGTH_LONG).show();

        AlertDialog.Builder builder1 = new AlertDialog.Builder(context);
        builder1.setMessage("Write your message here.");
        builder1.setCancelable(true);
        builder1.setPositiveButton("Yes",
                new DialogInterface.OnClickListener() {
                    public void onClick(DialogInterface dialog, int id) {
                       // dialog.cancel();
                    }
                });
        builder1.setNegativeButton("No",
                new DialogInterface.OnClickListener() {
                    public void onClick(DialogInterface dialog, int id) {
                       // dialog.cancel();
                    }
                });

        AlertDialog alert11 = builder1.create();
        alert11.show();

    }

无法通过服务

2 个答案: