（Android）有什么方法可以在收到Firebase云消息时显示AlertDialog（即使应用程序处于后台）？

Question

我想在收到 Firebase 云消息时显示 AlertDialog（Android 应用程序处于前台或后台）。

在前台，应用程序显示AlertDialog，但在后台，应用程序不显示AlertDialog。

MyFirebaseMessageService.kt

class MyFirebaseMessageService : FirebaseMessagingService() {
private val TAG = "fcm_tag"

override fun onMessageReceived(remoteMessage: RemoteMessage) {
    val title = remoteMessage.notification?.title
    val body = remoteMessage.notification?.body

    Log.d(TAG, "fcm title: $title")
    Log.d(TAG, "fcm body: $body")

    val alertDialogIntent = Intent(baseContext, AlertDialogActivity::class.java)
    alertDialogIntent.putExtra("title", title)
    alertDialogIntent.putExtra("body", body)

    try {
        PendingIntent.getActivity(
            baseContext,
            0,
            alertDialogIntent,
            PendingIntent.FLAG_IMMUTABLE
        ).send()
    } catch (e: Exception) {
        Log.d(TAG, "fcm error: $e")
    }
}
}

AlertDialogActivity.kt

class AlertDialogActivity : Activity() {
override fun onCreate(savedInstanceState: Bundle?) {
    super.onCreate(savedInstanceState)
    val bund = intent.extras
    val title = bund?.getString("title")
    val body = bund?.getString("body")

    AlertDialog.Builder(this).run {
        setTitle(title)
        setMessage(body)
        setPositiveButton("OK") { _, _ ->
            finish()
        }
        setCancelable(false)
        show()
    }
}
}

AndroidManifest.xml

<?xml version="1.0" encoding="utf-8"?>
<manifest xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:tools="http://schemas.android.com/tools"
    package="com.myproject">
    <uses-permission android:name="android.permission.FOREGROUND_SERVICE" />

    <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.MyProject">

        <service
            android:name=".MyFirebaseMessageService"
            android:enabled="true"
            android:exported="true">
            <intent-filter>
                <action android:name="com.google.firebase.MESSAGING_EVENT" />
            </intent-filter>
        </service>

        <activity
            android:name=".AlertDialogActivity"
            android:exported="true"
            android:theme="@style/Theme.AppCompat.DayNight.Dialog">
        </activity>

        <activity
            android:name=".MainActivity"
            android:exported="true"
            android:label="@string/app_name"
            android:theme="@style/Theme.MyProject">
            <intent-filter>
                <action android:name="android.intent.action.MAIN" />
                <category android:name="android.intent.category.LAUNCHER" />
            </intent-filter>
        </activity>

        <meta-data
            android:name="com.google.firebase.messaging.default_notification_channel_id"
            android:value="fcm_default_channel" />
        <meta-data
            android:name="com.google.firebase.messaging.default_notification_icon"
            android:resource="@drawable/ic_launcher_foreground" />
    </application>
</manifest>

Answer 1

AlertDialog alertDialog = new AlertDialog.Builder(this)
                    .setTitle("Title")
                    .setMessage("Are you sure?")
                    .create();

alertDialog.getWindow().setType(WindowManager.LayoutParams.TYPE_SYSTEM_ALERT);
alertDialog.show();

并请求此许可

<uses-permission android:name="android.permission.SYSTEM_ALERT_WINDOW" />