Firebase Cloud Messaging 推送通知在 Android 上不能在前台工作，只能在后台工作

Question

我正在尝试创建一个可以在满足某些要求时接收通知的应用。我尝试建立一个单独的项目来制作一个简单的云消息传递系统，但是当应用程序在前台运行时没有通知显示，只有在后台运行。

这是主要的 MapActivity 代码：

protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_maps);
        // Obtain the SupportMapFragment and get notified when the map is ready to be used.
        SupportMapFragment mapFragment = (SupportMapFragment) getSupportFragmentManager()
                .findFragmentById(R.id.map);
        mapFragment.getMapAsync(this);
        Intent intentBackgroundService = new Intent(this,FirebasePushNotification.class);
        startService(intentBackgroundService);
    }

firebase 消息类：

package com.example.traindetectionproject;

import androidx.annotation.NonNull;

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

public class FirebasePushNotification extends FirebaseMessagingService {


    public FirebasePushNotification() {
        super();
    }

    @Override
    public void onMessageReceived(@NonNull RemoteMessage remoteMessage) {
        super.onMessageReceived(remoteMessage);
    }
}

清单：

<?xml version="1.0" encoding="utf-8"?>
<manifest xmlns:android="http://schemas.android.com/apk/res/android"
    package="com.example.traindetectionproject">

    <!--
         The ACCESS_COARSE/FINE_LOCATION permissions are not required to use
         Google Maps Android API v2, but you must specify either coarse or fine
         location permissions for the "MyLocation" functionality.
    -->
    <uses-permission android:name="android.permission.ACCESS_FINE_LOCATION" />
    <uses-permission android:name="android.permission.ACCESS_NETWORK_STATE"/>
    <uses-permission android:name="android.permission.INTERNET"/>

    <application
        android:allowBackup="true"
        android:icon="@mipmap/ic_launcher"
        android:label="@string/app_name"
        android:roundIcon="@mipmap/ic_launcher_round"
        android:supportsRtl="true"
        android:theme="@style/Theme.Traindetectionproject">

        <!--
             The API key for Google Maps-based APIs is defined as a string resource.
             (See the file "res/values/google_maps_api.xml").
             Note that the API key is linked to the encryption key used to sign the APK.
             You need a different API key for each encryption key, including the release key that is used to
             sign the APK for publishing.
             You can define the keys for the debug and release targets in src/debug/ and src/release/.
        -->
        <meta-data
            android:name="com.google.android.geo.API_KEY"
            android:value="@string/google_maps_key" />

        <activity
            android:name=".MapsActivity"
            android:label="@string/title_activity_maps">
            <intent-filter>
                <action android:name="android.intent.action.MAIN" />

                <category android:name="android.intent.category.LAUNCHER" />
            </intent-filter>
        </activity>



    <service android:name=".FirebasePushNotification">
        <intent-filter>
            <action android:name="android.intent.action.RESPOND_VIA_MESSAGE"/>
        </intent-filter>
    </service>
    </application>

</manifest>

感谢您的建议

Answer 1

在前台，onMessageReceived 收到通知但未显示，那么您在onMessageReceived 中的代码应该编写并显示它，

当应用程序在后台时，通知会直接显示在通知栏中，而不会调用onMessageReceived

看这里：https://firebase.google.com/docs/cloud-messaging/android/receive

Answer 2

以下代码 sn-p 可能会帮助您找到解决方案

public class MyFirebaseMessagingService extends FirebaseMessagingService {
    @Override
    public void onNewToken ( @NonNull String s ) {
        super.onNewToken ( s );
    }

    @Override
    public void onMessageReceived ( @NonNull RemoteMessage remoteMessage ) {
        super.onMessageReceived ( remoteMessage );
        NotificationManager notificationManager = (NotificationManager) getSystemService ( Context.NOTIFICATION_SERVICE );
        if (!Objects.equals ( null, remoteMessage.getNotification () )) {
            if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.O) {
                NotificationChannel notificationChannel = new NotificationChannel ( NOTIFICATION_CHANNEL_ID, NOTIFICATION_CHANNEL_NAME, NotificationManager.IMPORTANCE_HIGH );
                notificationManager.createNotificationChannel ( notificationChannel );
            }
            NotificationCompat.Builder notificationBuilder = new NotificationCompat.Builder ( this, NOTIFICATION_CHANNEL_ID );
            notificationBuilder.setAutoCancel ( true )
                    .setStyle ( new NotificationCompat.BigTextStyle ().bigText ( remoteMessage.getNotification ().getBody () ) )
                    .setDefaults ( Notification.DEFAULT_ALL )
                    .setWhen ( System.currentTimeMillis () )
                    .setSmallIcon ( R.drawable.ic_notification_icon )
                    .setTicker ( remoteMessage.getNotification ().getTitle () )
                    .setPriority ( Notification.PRIORITY_MAX )
                    .setContentTitle ( remoteMessage.getNotification ().getTitle () )
                    .setContentText ( remoteMessage.getNotification ().getBody () );   
            notificationManager.notify ( 1, notificationBuilder.build () );
        }
    }
}

将此添加到您的 AndroidManifest.xml 之前的任何 Activity TAG

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