除了以上答案， 如果你正在使用FCM控制台测试推送通知，“data”键和对象没有添加到推送通知包。所以你不会收到详细的推送通知时，应用是后台或被杀。

在这种情况下，你必须选择你的后端管理控制台来测试应用程序的后台场景。

在这里，你将添加“data”键到你的推送包中。因此，详细的推送将如预期的那样显示出来。 希望这对少数人有帮助。

从服务器请求中完全删除通知有效负载。只发送数据并在onmessagerreceived()中处理它，否则当应用程序在后台或被杀死时，你的onmessagerreceived将不会被触发。

这是我从服务器发送的:

{
  "data":{
    "id": 1,
    "missedRequests": 5
    "addAnyDataHere": 123
  },
  "to": "fhiT7evmZk8:APA91bFJq7Tkly4BtLRXdYvqHno2vHCRkzpJT8QZy0TlIGs......"
}

你可以像这样在onMessageReceived(RemoteMessage message)中接收你的数据(假设我需要获取id)

Object obj = message.getData().get("id");
        if (obj != null) {
            int id = Integer.valueOf(obj.toString());
        }

类似地，你可以在onmessagerecreceived()内从服务器获得任何数据。

截至2019年7月

Android compileSdkVersion 28, buildToolsVersion 28.0.3和firebase-messaging:19.0.1

经过许多小时的研究，通过所有其他StackOverflow问题和答案，并尝试无数过时的解决方案，这个解决方案设法在以下3个场景中显示通知:

—应用程序在前台: 通知是由我的MyFirebaseMessagingService类的onmessagerreceived方法接收的

应用程序已经被杀死(它不在后台运行) FCM自动将通知发送到通知托盘。当用户触摸通知时，应用程序通过调用manifest中有android.intent.category.LAUNCHER的活动来启动。你可以在onCreate()方法中使用getIntent(). getextras()来获取通知的数据部分。

- App is in background: the notification is sent to the notification tray automatically by FCM. When the user touches the notification the app is brought to the foreground by launching the activity that has android.intent.category.LAUNCHER in the manifest. As my app has launchMode="singleTop" in that activity, the onCreate() method is not called because one activity of the same class is already created, instead the onNewIntent() method of that class is called and you get the data part of the notification there by using intent.getExtras().

步骤: 1-如果你这样定义你的应用程序的主活动:

<activity
    android:name=".MainActivity"
    android:label="@string/app_name"
    android:largeHeap="true"
    android:screenOrientation="portrait"
    android:launchMode="singleTop">
    <intent-filter>
        <action android:name=".MainActivity" />
        <action android:name="android.intent.action.MAIN" />
        <category android:name="android.intent.category.LAUNCHER" />
        <category android:name="android.intent.category.DEFAULT" />
    </intent-filter>
</activity>

2-在MainActivity.class的onCreate()方法中添加这些行

Intent i = getIntent();
Bundle extras = i.getExtras();
if (extras != null) {
    for (String key : extras.keySet()) {
        Object value = extras.get(key);
        Log.d(Application.APPTAG, "Extras received at onCreate:  Key: " + key + " Value: " + value);
    }
    String title = extras.getString("title");
    String message = extras.getString("body");
    if (message!=null && message.length()>0) {
        getIntent().removeExtra("body");
        showNotificationInADialog(title, message);
    }
}

和这些方法到同一个MainActivity.class:

@Override
public void onNewIntent(Intent intent){
    //called when a new intent for this class is created.
    // The main case is when the app was in background, a notification arrives to the tray, and the user touches the notification

    super.onNewIntent(intent);

    Log.d(Application.APPTAG, "onNewIntent - starting");
    Bundle extras = intent.getExtras();
    if (extras != null) {
        for (String key : extras.keySet()) {
            Object value = extras.get(key);
            Log.d(Application.APPTAG, "Extras received at onNewIntent:  Key: " + key + " Value: " + value);
        }
        String title = extras.getString("title");
        String message = extras.getString("body");
        if (message!=null && message.length()>0) {
            getIntent().removeExtra("body");
            showNotificationInADialog(title, message);
        }
    }
}


private void showNotificationInADialog(String title, String message) {

    // show a dialog with the provided title and message
    AlertDialog.Builder builder = new AlertDialog.Builder(this);
    builder.setTitle(title);
    builder.setMessage(message);
    builder.setPositiveButton("OK", new DialogInterface.OnClickListener() {
        public void onClick(DialogInterface dialog, int whichButton) {
            dialog.cancel();
        }
    });
    AlertDialog alert = builder.create();
    alert.show();
}

3-像这样创建MyFirebase类:

package com.yourcompany.app;

import android.content.Intent;
import android.util.Log;

import com.google.firebase.messaging.FirebaseMessagingService;
import com.google.firebase.messaging.RemoteMessage;

public class MyFirebaseMessagingService extends FirebaseMessagingService {


    public MyFirebaseMessagingService() {
        super();
    }

    @Override
    public void onMessageReceived(RemoteMessage remoteMessage) {

        Log.d(Application.APPTAG, "myFirebaseMessagingService - onMessageReceived - message: " + remoteMessage);

        Intent dialogIntent = new Intent(this, NotificationActivity.class);
        dialogIntent.addFlags(Intent.FLAG_ACTIVITY_NEW_TASK);
        dialogIntent.putExtra("msg", remoteMessage);
        startActivity(dialogIntent);

    }

}

4-创建一个新类NotificationActivity.class，如下所示:

package com.yourcompany.app;

import android.app.Activity;
import android.app.AlertDialog;
import android.content.DialogInterface;
import android.os.Bundle;
import android.util.Log;

import androidx.appcompat.app.AppCompatActivity;
import androidx.appcompat.view.ContextThemeWrapper;

import com.google.firebase.messaging.RemoteMessage;

public class NotificationActivity extends AppCompatActivity {

private Activity context;

@Override
protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    context = this;
    Bundle extras = getIntent().getExtras();

    Log.d(Application.APPTAG, "NotificationActivity - onCreate - extras: " + extras);

    if (extras == null) {
        context.finish();
        return;
    }

    RemoteMessage msg = (RemoteMessage) extras.get("msg");

    if (msg == null) {
        context.finish();
        return;
    }

    RemoteMessage.Notification notification = msg.getNotification();

    if (notification == null) {
        context.finish();
        return;
    }

    String dialogMessage;
    try {
        dialogMessage = notification.getBody();
    } catch (Exception e){
        context.finish();
        return;
    }
    String dialogTitle = notification.getTitle();
    if (dialogTitle == null || dialogTitle.length() == 0) {
        dialogTitle = "";
    }

    AlertDialog.Builder builder = new AlertDialog.Builder(new ContextThemeWrapper(context, R.style.myDialog));
    builder.setTitle(dialogTitle);
    builder.setMessage(dialogMessage);
    builder.setPositiveButton(getResources().getString(R.string.accept), new DialogInterface.OnClickListener() {
        public void onClick(DialogInterface dialog, int whichButton) {
            dialog.cancel();
        }
    });
    AlertDialog alert = builder.create();
    alert.show();

}

}

5-添加这些行到你的应用程序清单，在你的标签

    <service
        android:name=".MyFirebaseMessagingService"
        android:exported="false">
        <intent-filter>
            <action android:name="com.google.firebase.MESSAGING_EVENT" />
        </intent-filter>
    </service>

    <meta-data android:name="com.google.firebase.messaging.default_notification_channel_id" android:value="@string/default_notification_channel_id"/>

    <activity android:name=".NotificationActivity"
        android:theme="@style/myDialog"> </activity>

    <meta-data
        android:name="com.google.firebase.messaging.default_notification_icon"
        android:resource="@drawable/notification_icon"/>

    <meta-data
        android:name="com.google.firebase.messaging.default_notification_color"
        android:resource="@color/color_accent" />

6-在Application.java的onCreate()方法或MainActivity.class的onCreate()方法中添加这些行:

      // notifications channel creation
  if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.O) {
      // Create channel to show notifications.
      String channelId = getResources().getString("default_channel_id");
      String channelName = getResources().getString("General announcements");
      NotificationManager notificationManager = getSystemService(NotificationManager.class);
      notificationManager.createNotificationChannel(new NotificationChannel(channelId,
              channelName, NotificationManager.IMPORTANCE_LOW));
  }

完成了。

现在，为了在上述3个场景中很好地工作，你必须以以下方式从Firebase web控制台发送通知:

In the Notification section: Notification Title = Title to display in the notification dialog (optional) Notification text = Message to show to the user (required) Then in the Target section: App = your Android app and in Additional Options section: Android Notification Channel = default_channel_id Custom Data key: title value: (same text here than in the Title field of the Notification section) key: body value: (same text here than in the Message field of the Notification section) key:click_action value: .MainActivity Sound=Disabled Expires=4 weeks

你可以在模拟器中调试它与API 28谷歌播放。

编码快乐!

我觉得所有的响应都是不完整的，但它们都有一些你需要处理的东西，当你的应用程序在后台时，一个有数据的通知。

遵循这些步骤，你将能够在应用程序处于后台时处理通知。

添加一个intent-filter，像这样: <活动android: name = "。MainActivity”> <意图过滤器> <行动android: name = "。MainActivity " / > <category android:name="android.intent.category. default " /> < /意图过滤器>

到要处理通知数据的活动。

以以下格式发送通知: ｛ “通知”:{ "click_action": "。MainActivity”, "body": "new Symulti update !"， "title": "新的Symulti更新!"， "icon": "ic_notif_symulti"}， "data":{…}， "to": "c9Vaa3ReGdk:APA91bH-AuXgg3lDN2WMcBrNhJZoFtYF9"}

这里的关键是加法

"click_action" : ".MainActivity"

其中. mainactivity是您在步骤1中添加的带有intent-filter的活动。

从.MainActivity的onCreate中的通知中获取数据信息: onCreate(Bundle savedInstanceState) super.onCreate (savedInstanceState); setContentView (R.layout.activity_main); //获取通知数据信息 Bundle Bundle = getIntent().getExtras(); If (bundle != null) { //bundle必须包含通知的"data"字段发送的所有信息 ｝ ｝

这就是你需要做的。

要使firebase库在以下情况下调用onmessagerecreceived ()

应用程序在前台 后台应用程序 应用程序已被杀死

你不能把JSON键通知在你的请求到Firebase API，而是使用数据，见下文。

当你的应用程序处于后台或被杀死时，下面的消息将不会调用你的onmessagerreceived()，并且你不能自定义你的通知。

{
   "to": "/topics/journal",
   "notification": {
       "title" : "title",
       "text": "data!",
       "icon": "ic_notification"
    }
}

但是用这个方法就可以了

{
  "to": "/topics/dev_journal",
   "data": {
       "text":"text",
       "title":"",
       "line1":"Journal",
       "line2":"刊物"
   }
} 

基本上，消息是在参数RemoteMessage中与数据对象一起发送的，如Map<String, String>，然后您可以在这里的代码片段中管理onmessagerreceived中的通知

@Override
public void onMessageReceived(RemoteMessage remoteMessage) { 
     Map<String, String> data = remoteMessage.getData();

     //you can get your text message here.
     String text= data.get("text");


     NotificationCompat.Builder notificationBuilder = new NotificationCompat.Builder(this)
        // optional, this is to make beautiful icon
             .setLargeIcon(BitmapFactory.decodeResource(
                                    getResources(), R.mipmap.ic_launcher))  
        .setSmallIcon(smallIcon)  //mandatory
      .......
    /*You can read more on notification here:
    https://developer.android.com/training/notify-user/build-notification.html
    https://www.youtube.com/watch?v=-iog_fmm6mE
    */
}

因为从Firebase通知UI发送的显示消息只在应用程序处于前台时有效。对于数据消息，需要对FCM进行POST调用

步骤

安装高级休息客户端谷歌Chrome扩展 添加以下头文件 关键字:Content-Type，值:application/json 密钥:授权，值:Key ="您的服务器密钥" 添加正文 如果使用主题: ｛ "to": "/topics/topic_name"， "数据":{ "key1": "value1"， "key2": "value2"， ｝ ｝ 如果使用注册id: ｛ "registration_ids": "[{"id"}，{id1}]"， "数据":{ "key1": "value1"， "key2": "value2"， ｝ ｝

它!。现在像往常一样收听onmessagerreceived回调。

@Override
public void onMessageReceived(RemoteMessage remoteMessage) { 
     Map<String, String> data = remoteMessage.getData();
     String value1 = data.get("key1");
     String value2 = data.get("key2");
}