我构建了一个聊天应用程序。它工作正常。两个用户都可以轻松聊天 但是我遇到问题的地方是，如果一个用户的应用程序处于后台并且屏幕关闭，则无法通知用户收到该消息。

我现在想要的是在我的应用程序中，当 userA 向 userB 发送消息时，userB 移动设备空闲但应用程序在后台运行，userB 可以获得有关该消息的通知。 userB 可以打开聊天 Activity 并阅读消息。

我的 firebase 通知是从 firebase 控制台工作的，但我不知道如何调用实例 ID 并将其从 api 发送到特定设备，特定用户收到有关收到消息的通知，当应用程序屏幕关闭且应用程序正在运行时背景状态。我该如何实现？

我的 firebase 实例 ID 服务类在这里:

public class MyFirebaseInstanceIDService extends FirebaseInstanceIdService {
    private static final String TAG = "MyFirebaseIIDService";

    @Override
    public void onTokenRefresh() {

        //Getting registration token
        String refreshedToken = FirebaseInstanceId.getInstance().getToken();

        //Displaying token on logcat
        Log.d(TAG, "Refreshed token: " + refreshedToken);
    }

    private void sendRegistrationToServer(String token) {
        //You can implement this method to store the token on your server
        //Not required for current project
    }
}

这是我的 MyFirebase 消息服务类

public class MyFirebaseMessagingService extends FirebaseMessagingService {
    @Override
    public void onMessageReceived(RemoteMessage remoteMessage) {
        if (remoteMessage.getNotification().getBody() != null) {
            Log.e("FIREBASE", "Message Notification Body: " + remoteMessage.getNotification().getBody());
            sendNotification(remoteMessage);
        }
    }

    private void sendNotification(RemoteMessage remoteMessage) {
        RemoteMessage.Notification notification = remoteMessage.getNotification();
        Intent intent = new Intent(this, LoggedInView.class);
        intent.addFlags(Intent.FLAG_ACTIVITY_CLEAR_TOP);
        PendingIntent pendingIntent = PendingIntent.getActivity(this, 0, intent,
                PendingIntent.FLAG_ONE_SHOT);

        Uri defaultSoundUri= RingtoneManager.getDefaultUri(RingtoneManager.TYPE_NOTIFICATION);
        NotificationCompat.Builder notificationBuilder = new NotificationCompat.Builder(this)
                .setLargeIcon(BitmapFactory.decodeResource(getResources(),R.drawable.first_aid))
                .setSmallIcon(R.drawable.first_aid)
                .setContentTitle(notification.getTitle())
                .setContentText(notification.getBody())
                .setAutoCancel(true)
                .setSound(defaultSoundUri)
                .setContentIntent(pendingIntent);

        NotificationManager notificationManager =
                (NotificationManager) getSystemService(Context.NOTIFICATION_SERVICE);

        notificationManager.notify(0, notificationBuilder.build());
    }
}

这是我的聊天 Activity :

public class Chat extends AppCompatActivity {
    LinearLayout layout;
    ImageView sendButton,vidcall;
    EditText messageArea;
    ScrollView scrollView;
    Firebase reference1, reference2;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.act_chat);

        layout = (LinearLayout)findViewById(R.id.layout1);
        sendButton = (ImageView)findViewById(R.id.sendButton);
        vidcall = (ImageView)findViewById(R.id.vidBtnk);
        messageArea = (EditText)findViewById(R.id.messageArea);
        scrollView = (ScrollView)findViewById(R.id.scrollView);

        Firebase.setAndroidContext(this);
        reference1 = new Firebase("https://*******.firebaseio.com/messages/" + UserDetails.username + "_" + UserDetails.chatWith);
        reference2 = new Firebase("https://*******.firebaseio.com/messages/" + UserDetails.chatWith + "_" + UserDetails.username);

        sendButton.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View v) {
                String messageText = messageArea.getText().toString();

                if(!messageText.equals("")){
                    Map<String, String> map = new HashMap<String, String>();
                    map.put("message", messageText);
                    map.put("user", UserDetails.username);
                    reference1.push().setValue(map);
                    reference2.push().setValue(map);
                }
                messageArea.setText("");
            }
        });

        vidcall.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View v) {


                startActivity(new Intent(Chat.this, ConnectActivity.class));



            }
        });

        reference1.addChildEventListener(new ChildEventListener() {
            @Override
            public void onChildAdded(DataSnapshot dataSnapshot, String s) {
                Map map = dataSnapshot.getValue(Map.class);
                String message = map.get("message").toString();
                String userName = map.get("user").toString();

                if(userName.equals(UserDetails.username)){
                    addMessageBox("You:-\n" + message, 1);
                }
                else{
                    addMessageBox(UserDetails.chatWith + ":-\n" + message, 2);
                }
            }

            @Override
            public void onChildChanged(DataSnapshot dataSnapshot, String s) {

            }

            @Override
            public void onChildRemoved(DataSnapshot dataSnapshot) {

            }

            @Override
            public void onChildMoved(DataSnapshot dataSnapshot, String s) {

            }

            @Override
            public void onCancelled(FirebaseError firebaseError) {

            }
        });
    }


   // boolean doubleBackToExitPressedOnce = false;

    @Override
    public void onBackPressed() {

        AlertDialog.Builder builder1 = new AlertDialog.Builder(Chat.this);
        builder1.setMessage("CAUTION! -> Do Wish to End this Session");
        builder1.setCancelable(true);
        builder1.setPositiveButton(
                "Yes",
                new DialogInterface.OnClickListener() {
                    public void onClick(DialogInterface dialog, int id) {

                        finish();

                        dialog.cancel();
                    }
                });

        builder1.setNegativeButton(
                "No",
                new DialogInterface.OnClickListener() {
                    public void onClick(DialogInterface dialog, int id) {
                        dialog.cancel();
                    }
                });

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


    }


    public void addMessageBox(String message, int type){
        TextView textView = new TextView(Chat.this);
        textView.setText(message);
        LinearLayout.LayoutParams lp = new LinearLayout.LayoutParams(ViewGroup.LayoutParams.MATCH_PARENT, ViewGroup.LayoutParams.WRAP_CONTENT);
        lp.setMargins(0, 0, 0, 10);
        textView.setLayoutParams(lp);

        if(type == 1) {
            textView.setBackgroundResource(R.drawable.rounded_corner1);
        }
        else{
            textView.setBackgroundResource(R.drawable.rounded_corner2);
        }

        layout.addView(textView);
        scrollView.fullScroll(View.FOCUS_DOWN);
    }
}

最佳答案

您需要一个在后台运行的服务来捕获推送通知并将其显示给用户，而这正是 Firebase 通知服务为您提供的。我有这个(你必须修改它才能在出现通知时执行你想执行的操作):

public class MyFirebaseMessagingService extends FirebaseMessagingService {

    @Override
    public void onMessageReceived(RemoteMessage remoteMessage) {
        if (remoteMessage.getNotification().getBody() != null) {
            Log.e("FIREBASE", "Message Notification Body: " + remoteMessage.getNotification().getBody());
            sendNotification(remoteMessage);
        }
    }

    private void sendNotification(RemoteMessage remoteMessage) {
        RemoteMessage.Notification notification = remoteMessage.getNotification();
        Intent intent = new Intent(this, MainActivity.class);
        intent.addFlags(Intent.FLAG_ACTIVITY_CLEAR_TOP);
        PendingIntent pendingIntent = PendingIntent.getActivity(this, 0, intent,
                PendingIntent.FLAG_ONE_SHOT);

        Uri defaultSoundUri= RingtoneManager.getDefaultUri(RingtoneManager.TYPE_NOTIFICATION);
        NotificationCompat.Builder notificationBuilder = new NotificationCompat.Builder(this)
                .setLargeIcon(BitmapFactory.decodeResource(getResources(),R.drawable.logo_gris))
                .setSmallIcon(R.drawable.logo_gris)
                .setContentTitle(notification.getTitle())
                .setContentText(notification.getBody())
                .setAutoCancel(true)
                .setSound(defaultSoundUri)
                .setContentIntent(pendingIntent);

        NotificationManager notificationManager =
                (NotificationManager) getSystemService(Context.NOTIFICATION_SERVICE);

        notificationManager.notify(0, notificationBuilder.build());
    }


}

关于android - 当应用程序在后台时通过 api 显示 Firebase 消息 onReceived 的通知，我们在Stack Overflow上找到一个类似的问题： https://stackoverflow.com/questions/41750548/