android从前台服务启动一个activity

Question

public class LockScreenService extends Service {

    public static final int LOCK_SCREEN_SERVICE_NOTIFICATION_ID = 1;
    public static final int SERVICE_NOTIFICATION_PENDING_INTENT_REQUEST_CODE = -10;
    private BroadcastReceiver screenOnReceiver;

    @Override
    public void onCreate() {
        super.onCreate();
        Toast.makeText(this, "start", Toast.LENGTH_SHORT).show();
        localeSet(this);
        startForeground(LOCK_SCREEN_SERVICE_NOTIFICATION_ID, createServiceNotification());

        screenOnReceiver = new BroadcastReceiver() {
            @Override
            public void onReceive(Context context, Intent intent) {

                Toast.makeText(context, "screen on!", Toast.LENGTH_SHORT).show();

            }
        };

        IntentFilter intentFilter = new IntentFilter();
        intentFilter.addAction(Intent.ACTION_SCREEN_ON);

        registerReceiver(screenOnReceiver, intentFilter);
    }

    @Override
    public int onStartCommand(Intent intent, int flags, int startId) {
        return START_STICKY;
    }

    @Override
    public void onDestroy() {
        super.onDestroy();
        if (screenOnReceiver != null) {
            unregisterReceiver(screenOnReceiver);
            screenOnReceiver = null;
        }
    }

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


    private Notification createServiceNotification() {

        Intent notificationIntent = new Intent(this, SplashActivity.class); // activity you wanna show when the notification is clicked
        int flags = Build.VERSION.SDK_INT >= Build.VERSION_CODES.S ? PendingIntent.FLAG_UPDATE_CURRENT | PendingIntent.FLAG_IMMUTABLE : PendingIntent.FLAG_UPDATE_CURRENT;
        PendingIntent pendingIntent = PendingIntent.getActivity(this, SERVICE_NOTIFICATION_PENDING_INTENT_REQUEST_CODE, notificationIntent, flags);

        NotificationCompat.Builder builder = new NotificationCompat.Builder(this, getResources().getString(R.string.service_notification_channel_id))
                .setSmallIcon(R.drawable.ic_stat_notification_icon)
                .setContentTitle(getResources().getString(R.string.service_notification_title))
                .setContentText(getResources().getString(R.string.service_notification_content))
                .setContentIntent(pendingIntent)
                .setPriority(NotificationCompat.PRIORITY_DEFAULT);

        return builder.build();

    }


    private void localeSet(Context context) {

        SharedPreferences prefs = context.getSharedPreferences("AppSettings", Context.MODE_PRIVATE);
        String langCode = prefs.getString("languageCode", "");

        Locale locale = new Locale(langCode);
        Locale.setDefault(locale);

        Configuration config = context.getResources().getConfiguration();
        config.setLocale(locale);

        context.getResources().updateConfiguration(config, context.getResources().getDisplayMetrics());
    }

嗨！我是一名新手程序员，有很多东西需要学习。 我正在尝试制作一个 Android 应用程序，它是在锁定屏幕上显示用户待办事项列表的待办事项应用程序。

我制作了一个前台服务，其中有一个广播接收器实例作为字段，并且广播接收器监听“屏幕打开”操作，因此当用户打开屏幕时，应用程序会向用户显示一个活动。正如您在上面的代码中所看到的，目前，当屏幕打开时，应用程序会向您显示“屏幕打开！”看起来效果很好。

        screenOnReceiver = new BroadcastReceiver() {
            @Override
            public void onReceive(Context context, Intent intent) {
                if (Intent.ACTION_SCREEN_ON.equals(intent.getAction())) {

                    Toast.makeText(context, "screen on", Toast.LENGTH_SHORT).show();
//                    // Intent to launch the desired activity
                    Intent activityIntent = new Intent(context, LockScreenActivity.class);
//
//                    // Include these flags to launch the activity even if the device is locked
                    activityIntent.addFlags(Intent.FLAG_ACTIVITY_NEW_TASK
                            | Intent.FLAG_ACTIVITY_CLEAR_TASK
                            | Intent.FLAG_ACTIVITY_CLEAR_TOP);
//
//                    // Starting the activity
                    startActivity(activityIntent);
                }
            }
        };

然后我以这种方式更改了广播接收器代码，它有点在锁定屏幕上打开了一个活动。但是当我关闭应用程序时，即使前台服务处于活动状态，应用程序也没有打开活动。它只显示“屏幕打开！”吐司。即使应用程序已关闭，我应该如何从服务中弹出活动？

我一直在寻找这个，但他们没有关于这个的最新信息。 我也读过 https://developer.android.com/guide/components/activities/background-starts 我让应用程序向用户询问 SYSTEN_ALERT_WINDOW 权限，但即使获得了权限，当应用程序关闭时，应用程序也没有在锁定屏幕上显示活动。

※ 抱歉我的英语不好，我的母语不是英语。

Answer 1

必须在服务内的

PendingIntent

上添加

Notification

：

/** The content {@link Intent}, which leads to {@link MainActivity}. */
@NonNull
private PendingIntent getContentPendingIntent() {
    Intent contentIntent = new Intent(this, MainActivity.class);
    contentIntent.setData(Uri.parse("someapp://somedeeplink")); // optional.
    return PendingIntent.getActivity(this, 0, contentIntent, this.getIntentFlags());
}

它的分配是这样的：

NotificationCompat.Builder builder = this.getNotificationBuilder();
builder.setContentIntent(this.getContentPendingIntent());