我有一个聊天应用程序，我试图在收到新消息后向用户显示通知。

启动活动后，我将按以下方式调用onStart：

@Override
protected void onStart() {
    super.onStart();
    popNotification();
}

popNotification是为了检查我的数据库中是否有任何更新而调用的类。如果是，我调用另一个名为AddNotification()

public void popNotification() {

    db.collection("Users").document(auth.getUid()).collection("MyChats")
            .addsnapshotListener(new EventListener<Querysnapshot>() {
                @Override
                public void onEvent(@Nullable Querysnapshot value,@Nullable FirebaseFirestoreException e) {
                    if (e != null) {
                        Log.w("","Listen failed.",e);
                        return;
                    }

                    for (QueryDocumentsnapshot doc : value) {

                        if (doc.getId() != null) {
                            DocumentReference docRef = db.collection("Users").document(auth.getUid()).collection("MyChats").document(doc.getId());
                            docRef.get().addOnCompleteListener(new OnCompleteListener<Documentsnapshot>() {
                                @Override
                                public void onComplete(@NonNull Task<Documentsnapshot> task) {
                                    if (task.isSuccessful()) {
                                        Documentsnapshot document = task.getResult();
                                        if (document.exists()) {
                                            if(document.getLong("LastMessageTime") > document.getLong("lastChatVisited")){
                                                AddNotification();
                                            }
                                        } else {
                                            Log.d("","No such document");
                                        }
                                    } else {
                                        Log.d("","get failed with ",task.getException());
                                    }
                                }
                            });
                        }
                    }
                }
            });
}

和AddNotification()：

private void AddNotification(){
    FirebaseInstanceId.getInstance().getInstanceId()
            .addOnCompleteListener(new OnCompleteListener<InstanceIdResult>() {
                @Override
                public void onComplete(@NonNull Task<InstanceIdResult> task) {
                    if (!task.isSuccessful()) {
                        Log.w("","getInstanceId failed",task.getException());
                        return;
                    }

                    // Get new Instance ID token
                    String token = task.getResult().getToken();

                    try {

                        String title = "TEST ";
                        MyTaskParams params = new MyTaskParams(token,title,"TTT!");
                        MyTask myTask = new MyTask();
                        myTask.execute(params);

                    } catch (Exception ex) {
                        ex.printStackTrace();
                    }
                }
            });
}

最后一件事是mytask：

private class MyTask extends AsyncTask<MyTaskParams,Void,Void> {
    @Override
    protected Void doInBackground(MyTaskParams... params) {
        String userDeviceIdKey = params[0].url;
        String title = params[0].title;
        String body = params[0].body;

        String authKey = "XXX";   // You FCM AUTH key
        String FMCurl = "https://fcm.googleapis.com/fcm/send";
        URL url;
        try {
            url = new URL(FMCurl);
            HttpURLConnection conn = (HttpURLConnection) url.openConnection();

            conn.setUseCaches(false);
            conn.setDoInput(true);
            conn.setDoOutput(true);

            conn.setRequestMethod("POST");
            conn.setRequestProperty("Authorization","key="+authKey);
            conn.setRequestProperty("Content-Type","application/json");

            JSONObject json = new JSONObject();
            json.put("to",userDeviceIdKey);
            json.put("priority","high");
            JSONObject info = new JSONObject();
            info.put("title",title);   // Notification title
            info.put("body",body); // Notification body
            json.put("data",info);

            OutputStreamWriter wr = new OutputStreamWriter(conn.getOutputStream());
            wr.write(json.toString());
            wr.flush();
            conn.getInputStream();
        } catch (MalformedURLException e) {
            e.printStackTrace();
        } catch (IOException e) {
            e.printStackTrace();
        } catch (JSONException e) {
            e.printStackTrace();
        }

        return null;
    }
}

现在，问题在于我没有收到任何通知。

我插入Logs是为了检查代码是否在此处运行，并且似乎通过了所有必需的功能，但是仍然没有显示任何内容。

我添加了优先级=高，因为我读了它可能会影响，但没有帮助。

我的消息类别是：

public class MyFirebaseMessagingService extends FirebaseMessagingService {
    private static final String TAG = "FCM Service";

@Override
public void onmessageReceived(RemoteMessage remoteMessage) {

    Log.d(TAG,"From: " + remoteMessage.getFrom());
    Log.d(TAG,"Notification Message Body: " + remoteMessage.getData().get("body"));

    NotificationCompat.Builder builder = new NotificationCompat.Builder(this,"29358305")
            .setSmallIcon(R.drawable.ic_launcher_custom_background)
            .setContentTitle(remoteMessage.getData().get("title"))
            .setContentText(remoteMessage.getData().get("body"))
            .setStyle(new NotificationCompat.BigTextStyle()
                    .bigText(remoteMessage.getData().get("body")))
            .setLargeIcon(BitmapFactory.decodeResource(getapplicationContext().getResources(),R.mipmap.ic_launcher))
            .setPriority(NotificationCompat.PRIORITY_DEFAULT);

    //createNotificationChannel();

    NotificationmanagerCompat notificationmanager = NotificationmanagerCompat.from(this);

    notificationmanager.notify(235345305,builder.build());

}

}

编辑：

在创建通知时，我也尝试使用以下内容而没有任何改进：

public class MyFirebaseMessagingService extends FirebaseMessagingService {
    private static final String TAG = "FCM Service";

    @Override
    public void onmessageReceived(RemoteMessage remoteMessage) {

        Log.d(TAG,"From: " + remoteMessage.getFrom());
        Log.d(TAG,"Notification Message Body: " + remoteMessage.getData().get("body"));


        createNotificationChannel();
        notifyThis(remoteMessage.getData().get("title"),remoteMessage.getData().get("body"));

    }

private void createNotificationChannel() {
    // Create the NotificationChannel,but only on API 26+ because
    // the NotificationChannel class is new and not in the support library
    if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.O) {
        CharSequence name = "ABC";
        String description = "ABCDE";
        int importance = Notificationmanager.IMPORTANCE_DEFAULT;
        NotificationChannel channel = new NotificationChannel("191919",name,importance);
        channel.setDescription(description);
        // Register the channel with the system; you can't change the importance
        // or other notification behaviors after this
        Notificationmanager notificationmanager = getSystemService(Notificationmanager.class);
        notificationmanager.createNotificationChannel(channel);
    }
}

public void notifyThis(String title,String message) {
    NotificationCompat.Builder mBuilder = new NotificationCompat.Builder(this,"191919")
            .setSmallIcon(R.drawable.ic_launcher_background)
            .setContentTitle(title)
            .setContentText(message)
            .setPriority(NotificationCompat.PRIORITY_DEFAULT);

    NotificationmanagerCompat notificationmanager = NotificationmanagerCompat.from(this);

    // notificationId is a unique int for each notification that you must define
    notificationmanager.notify(0,mBuilder.build());
}

我是否还需要添加onPause或其他内容才能使其正常工作，或者我还有其他一些我无法理解的错误？

谢谢