Question

我一直在尝试阅读有关如何将消息从一个设备发送到另一个设备的官方文档和指南。我已经在实时数据库中保存了两个设备的注册令牌，因此我有另一个设备的注册令牌。我尝试了以下方式发送消息

RemoteMessage message = new RemoteMessage.Builder(getRegistrationToken())
                    .setMessageId(incrementIdAndGet())
                    .addData("message", "Hello")
                    .build();
FirebaseMessaging.getInstance().send(message);

然而这不起作用。其他设备不接收任何消息。我甚至不确定，如果我可以使用上游消息发送来进行设备到设备的通信。

PS：我只是想知道使用FCM是否可以实现设备到设备的消息传递？如果是，那么我使用的代码是否有问题？如果是，那么正确的方法是什么。

更新
我的问题是询问设备到设备的消息传递是否可以在不使用firebase之外的任何单独的服务器的情况下是否可以进行消息传递，如果是的话，是否可以，因为没有关于它的文档。我不明白这里要解释什么？无论如何，我得到了答案，并在问题重新开始后将其更新为答案。

Answer 1

Firebase有两项功能可以向设备发送消息：

Firebase控制台中的“通知”面板允许您向特定设备，用户组或用户订阅的主题发送通知。
通过调用Firebase云消息传递API，您可以使用您喜欢的任何定位策略发送消息。调用FCM API需要访问您的服务器密钥，您不应在客户端设备上公开该密钥。这就是为什么你应该总是在应用服务器上运行这样的代码。

Firebase documentation以可视方式显示：

Firebase云消息传递不支持将消息从一台设备直接发送到另一台设备。

更新：我写了一篇详细介绍how to send notifications between Android devices using Firebase Database, Cloud Messaging and Node.js的博客文章。

更新2 ：您现在还可以使用Cloud Functions for Firebase安全地发送邮件，而无需启动服务器。请参阅this sample use-case开始使用。

Answer 2

警告我们在任何地方都没有提及此方法，这是一个非常重要的原因。这会在APK中公开您的服务器密钥你穿上每个客户端设备。它可以（因此将）取而代之在那里，可能会导致滥用您的项目。我强烈推荐反对采取这种方法，除了你只穿的应用程序你自己的设备。 - Frank van Puffelen

好的，所以Frank的答案是正确的，Firebase本身不支持设备到设备的消息传递。然而，那里有一个漏洞。 Firebase服务器无法识别您是从实际服务器发送请求还是从设备执行此操作。

所以你要做的就是将Post Request发送到Firebase的消息服务器以及服务器密钥。 请记住，服务器密钥不应该在设备上，但如果您希望使用Firebase Messaging进行设备到设备的消息传递，则没有其他选择。

我使用OkHTTP而不是默认的方式调用Rest API。代码是这样的 -

public static final String FCM_MESSAGE_URL = "https://fcm.googleapis.com/fcm/send";
OkHttpClient mClient = new OkHttpClient();
public void sendMessage(final JSONArray recipients, final String title, final String body, final String icon, final String message) {

        new AsyncTask<String, String, String>() {
            @Override
            protected String doInBackground(String... params) {
                try {
                    JSONObject root = new JSONObject();
                    JSONObject notification = new JSONObject();
                    notification.put("body", body);
                    notification.put("title", title);
                    notification.put("icon", icon);

                    JSONObject data = new JSONObject();
                    data.put("message", message);
                    root.put("notification", notification);
                    root.put("data", data);
                    root.put("registration_ids", recipients);

                    String result = postToFCM(root.toString());
                    Log.d(TAG, "Result: " + result);
                    return result;
                } catch (Exception ex) {
                    ex.printStackTrace();
                }
                return null;
            }

            @Override
            protected void onPostExecute(String result) {
                try {
                    JSONObject resultJson = new JSONObject(result);
                    int success, failure;
                    success = resultJson.getInt("success");
                    failure = resultJson.getInt("failure");
                    Toast.makeText(getCurrentActivity(), "Message Success: " + success + "Message Failed: " + failure, Toast.LENGTH_LONG).show();
                } catch (JSONException e) {
                    e.printStackTrace();
                    Toast.makeText(getCurrentActivity(), "Message Failed, Unknown error occurred.", Toast.LENGTH_LONG).show();
                }
            }
        }.execute();
    }

String postToFCM(String bodyString) throws IOException {
        RequestBody body = RequestBody.create(JSON, bodyString);
        Request request = new Request.Builder()
                .url(FCM_MESSAGE_URL)
                .post(body)
                .addHeader("Authorization", "key=" + SERVER_KEY)
                .build();
        Response response = mClient.newCall(request).execute();
        return response.body().string();
    }

我希望Firebase将来会有更好的解决方案。但到那时，我认为这是唯一的方法。另一种方式是发送主题消息或组消息。但这不属于问题的范围。

<强>更新
JSONArray的定义如下 -

JSONArray regArray = new JSONArray(regIds);

regIds是一个注册ID的String数组，您希望将此消息发送到。请记住，注册ID必须始终在数组中，即使您希望将其发送给单个收件人。

Answer 3

我也一直在我的原型中使用直接设备来设备gcm消息。它一直运作良好。我们没有任何服务器。我们使用sms / text交换GCM reg id，然后使用GCM进行通信。我在这里放置与GCM处理相关的代码

**************发送GCM消息*************

//Sends gcm message Asynchronously
public class GCM_Sender extends IntentService{
    final String API_KEY = "****************************************";

    //Empty constructor
    public GCM_Sender() {
        super("GCM_Sender");
    }

    //Processes gcm send messages
    @Override
    protected void onHandleIntent(Intent intent) {  

        Log.d("Action Service", "GCM_Sender Service Started");
        //Get message from intent
        String msg = intent.getStringExtra("msg");
        msg =  "\"" + msg + "\"";
        try{
            String ControllerRegistrationId = null;                 
            //Check registration id in db       
            if(RegistrationIdAdapter.getInstance(getApplicationContext()).getRegIds().size() > 0 ) {
                String controllerRegIdArray[] = RegistrationIdAdapter.getInstance(getApplicationContext()).getRegIds().get(1);
                if(controllerRegIdArray.length>0)
                    ControllerRegistrationId = controllerRegIdArray[controllerRegIdArray.length-1];

                if(!ControllerRegistrationId.equalsIgnoreCase("NULL")){
                    // 1. URL
                    URL url = new URL("https://android.googleapis.com/gcm/send");
                    // 2. Open connection
                    HttpURLConnection urlConnection = (HttpURLConnection) url.openConnection();
                    // 3. Specify POST method
                    urlConnection.setRequestMethod("POST");
                    // 4. Set the headers
                    urlConnection.setRequestProperty("Content-Type", "application/json");
                    urlConnection.setRequestProperty("Authorization", "key=" + API_KEY);
                    urlConnection.setDoOutput(true);
                    // 5. Add JSON data into POST request body
                    JSONObject obj = new JSONObject("{\"time_to_live\": 0,\"delay_while_idle\": true,\"data\":{\"message\":" + msg + "},\"registration_ids\":[" + ControllerRegistrationId + "]}");
                    // 6. Get connection output stream
                    OutputStreamWriter out = new OutputStreamWriter(urlConnection.getOutputStream());
                    out.write(obj.toString());
                    out.close();
                    // 6. Get the response
                    int responseCode = urlConnection.getResponseCode();

                    BufferedReader in = new BufferedReader(new InputStreamReader(urlConnection.getInputStream()));
                    String inputLine;
                    StringBuffer response = new StringBuffer();
                    while ((inputLine = in.readLine()) != null){
                        response.append(inputLine);
                    }
                    in.close();
                    Log.d("GCM getResponseCode:", new Integer(responseCode).toString());
                }else{
                    Log.d("GCM_Sender:","Field REGISTRATION_TABLE is null");
                }
            }else {
                Log.d("GCM_Sender:","There is no Registration ID in DB ,please sync devices");
            }
        } catch (Exception e) {
            e.printStackTrace();
            //MessageSender.getInstance().sendMessage(msg, Commands.SMS_MESSAGE);
        } 
    }

    //Called when service is no longer alive
    @Override
    public void onDestroy() {
        super.onDestroy();
        //Do a log that GCM_Sender service has been destroyed
        Log.d("Action Service", "GCM_Sender Service Destroyed");
    }
}

**************收到GCM讯息*************

public class GCM_Receiver extends WakefulBroadcastReceiver {
    public static final String RETRY_ACTION ="com.google.android.c2dm.intent.RETRY";
    public static final String REGISTRATION ="com.google.android.c2dm.intent.REGISTRATION";
    public SharedPreferences preferences;

    //Processes Gcm message .
    @Override
    public void onReceive(Context context, Intent intent) {
        ComponentName comp = new ComponentName(context.getPackageName(),
                GCMNotificationIntentService.class.getName());
        //Start GCMNotificationIntentService to handle gcm message asynchronously
        startWakefulService(context, (intent.setComponent(comp)));
        setResultCode(Activity.RESULT_OK);

        /*//Check if DatabaseService is running .
        if(!DatabaseService.isServiceRunning) {
            Intent dbService = new Intent(context,DatabaseService.class);
            context.startService(dbService);
        }*/
        //Check if action is RETRY_ACTION ,if it is then do gcm registration again .
        if(intent.getAction().equals(RETRY_ACTION)) {
            String registrationId = intent.getStringExtra("registration_id");

            if(TextUtils.isEmpty(registrationId)){
                DeviceRegistrar.getInstance().register(context);
            }else {
                //Save registration id to prefs .
                preferences = PreferenceManager.getDefaultSharedPreferences(context);
                SharedPreferences.Editor editor = preferences.edit();
                editor.putString("BLACKBOX_REG_ID",registrationId);
                editor.commit();
            }
        } else if (intent.getAction().equals(REGISTRATION)) {
        }

    }
}

//Processes gcm messages asynchronously .
public class GCMNotificationIntentService extends IntentService{
    public static final int NOTIFICATION_ID = 1;
    private NotificationManager mNotificationManager;
    String gcmData;
    private final String TAG = "GCMNotificationIntentService";

    //Constructor with super().
    public GCMNotificationIntentService() {
        super("GcmIntentService");
    }

    //Called when startService() is called by its Client .
    //Processes gcm messages .
    @Override
    protected void onHandleIntent(Intent intent) {

        Log.d("GCMNotificationIntentService", "GCMNotificationIntentService Started");
        Bundle extras = intent.getExtras();
        //Get instance of GoogleCloudMessaging .
        GoogleCloudMessaging gcm = GoogleCloudMessaging.getInstance(this);
        //Get gcm message type .
        String messageType = gcm.getMessageType(intent);

        if (!extras.isEmpty()) {
            if (GoogleCloudMessaging.MESSAGE_TYPE_SEND_ERROR
                    .equals(messageType)) {
                sendNotification("Send error: " + extras.toString());
            } else if (GoogleCloudMessaging.MESSAGE_TYPE_DELETED
                    .equals(messageType)) {
                sendNotification("Deleted messages on server: "
                        + extras.toString());
            } else if (GoogleCloudMessaging.MESSAGE_TYPE_MESSAGE
                    .equals(messageType)) {
                Log.i(TAG, "Completed work @ " + SystemClock.elapsedRealtime());

                gcmData = extras.getString("message");
                Intent actionService = new Intent(getApplicationContext(),Action.class);    
                actionService.putExtra("data", gcmData);
                //start Action service .
                startService(actionService);

                //Show push notification .
                sendNotification("Action: " + gcmData);
                //Process received gcmData.

                Log.d(TAG,"Received Gcm Message from Controller : " + extras.getString("message"));
            }
        }
        GCM_Receiver.completeWakefulIntent(intent);
    }

    //Shows notification on device notification bar .
    private void sendNotification(String msg) {
        mNotificationManager = (NotificationManager) this.getSystemService(Context.NOTIFICATION_SERVICE);
        Intent notificationIntent = new Intent(this, BlackboxStarter.class);
        //Clicking on GCM notification add new layer of app.
        notificationIntent.setFlags( Intent.FLAG_ACTIVITY_CLEAR_TASK | Intent.FLAG_ACTIVITY_NEW_TASK);
        PendingIntent contentIntent = PendingIntent.getActivity(this, 0,notificationIntent, PendingIntent.FLAG_CANCEL_CURRENT);
        NotificationCompat.Builder mBuilder = new NotificationCompat.Builder(
                this).setSmallIcon(R.drawable.gcm_cloud)
                .setContentTitle("Notification from Controller")
                .setStyle(new NotificationCompat.BigTextStyle().bigText(msg))
                .setContentText(msg);
        mBuilder.setContentIntent(contentIntent);
        mNotificationManager.notify(NOTIFICATION_ID, mBuilder.build());
        //Play default notification
        try {
            Uri notification = RingtoneManager.getDefaultUri(RingtoneManager.TYPE_NOTIFICATION);
            Ringtone r = RingtoneManager.getRingtone(getApplicationContext(), notification);
            r.play();
        } catch (Exception e) {
            e.printStackTrace();
        }
    }

    //Called when service is no longer be available .
    @Override
    public void onDestroy() {
        // TODO Auto-generated method stub
        super.onDestroy();
        Log.d("GCMNotificationIntentService", "GCMNotificationIntentService Destroyed");
    }

}

Answer 4

我迟到但是上面的解决方案帮助我写下这个简单的答案，你可以从android应用程序直接发送你的消息到android设备，这是我做过的简单实现，它对我很有用。

编译android排球库
```
for ... %%c
```
只需复制粘贴这个简单的功能;）你的生活就像黄油刀一样变得光滑。：D
```
for
```

注意如果您要向主题发送消息，则可以将参数 instanceIdToken 更改为 / topics / topicName 。对于组，实现是相同的，但您只需要处理参数。 checkout Firebase documentation and you can pass those parameters. 如果您遇到任何问题，请与我们联系。

Answer 5

根据October 2, 2018更新的新文档，您必须按照以下方式发送发帖请求

https://fcm.googleapis.com/fcm/send
Content-Type:application/json
Authorization:key=AIzaSyZ-1u...0GBYzPu7Udno5aA //Server key

{
    "to": "sent device's registration token",
    "data": {
       "hello": "message from someone",
    }
}

要获取设备的注册令牌，请扩展FirebaseMessagingService并覆盖onNewToken(String token) 有关更多信息，请参阅文档https://firebase.google.com/docs/cloud-messaging/android/device-group

如何使用Firebase Messaging发送一对一消息

5 个答案: