我的应用关闭时的Firebase数据库后台服务

Question

当Firebase数据库值更改时，我需要在android应用程序中查看Toast消息。当应用关闭时，它也应该在后台运行，并且在那个时候没有在最近的应用中运行。我还需要查看带有后台服务的Toast消息。 Firebase实时数据库上的哪个值更改。

是否可以在android中做到这一点？请告诉我某人该怎么做以及我需要在Android应用中执行哪些服务？

下面是我的源代码

AndroidManifest.xml

<manifest xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:tools="http://schemas.android.com/tools"
package="com.assistant.firebasebackground">

<application
    android:name="com.assistant.firebasebackground.FireBaseService"
    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/AppTheme">
    <activity android:name=".MainActivity">
        <intent-filter>
            <action android:name="android.intent.action.MAIN" />

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

    <service android:name=".FireBaseService">
        <intent-filter>
            <action android:name="com.assistant.firebasebackground.FirebaseBackgroundService" />
        </intent-filter>

    </service>

    <receiver android:name=".StartFirebaseAtBoot" >
        <intent-filter>
            <action android:name="android.intent.action.BOOT_COMPLETED" >
            </action>
        </intent-filter>
    </receiver>
</application>

MainActivity.java

public class MainActivity extends AppCompatActivity {

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

    Intent intent = new Intent(this, FireBaseService.class);
    startActivity(intent);
}}

FireBaseService.java

public class FireBaseService extends Service {

FirebaseDatabase firebaseDatabase;
private DatabaseReference f;

    @Override
    public void onCreate() {
        super.onCreate();

        firebaseDatabase = FirebaseDatabase.getInstance();
        f = firebaseDatabase.getReference("https://firebaseurl.com/");
        f.addValueEventListener(new ValueEventListener() {
            @Override
            public void onDataChange(DataSnapshot dataSnapshot) {
                if (dataSnapshot.getValue() != null) {

                   Toast.makeText(FireBaseService.this, dataSnapshot.getValue().toString(), Toast.LENGTH_SHORT).show();
                }
            }

            @Override
            public void onCancelled(@NonNull DatabaseError databaseError) {

            }

        });
    }

    @Nullable
    @Override
    public IBinder onBind(Intent intent) {
        return null;
    }}

StartFirebaseAtBoot.java

public class StartFirebaseAtBoot extends BroadcastReceiver {

        @Override
        public void onReceive(Context context, Intent intent) {
            Intent i = new Intent(context,FireBaseService.class);
            context.startActivity(i);
        }
    }