Android : 类似于文件管理器，在 Android 设备中获取最近添加的媒体

Question

我正在开发一个应用程序，当用户通过任何方式（无论是下载还是传输）插入新图像、视频、音频或 apk 时，我必须立即通知用户，类似于文件管理器应用程序所做的.我不知道从哪里开始。谢谢

Answer 1

这是我的完整代码，用于在设备中添加新媒体（图像、音频或视频）时通知用户。它可能对某人有所帮助。此外，我会在添加新媒体后立即显示推送通知。

已编辑（已解决的问题如下）
1.仅在添加媒体时通知用户，而不是删除。

    public class MediaTrackerService extends Service {

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

    @Override
    public int onStartCommand(Intent intent, int flags, int startId) {
        // images
        getContentResolver().registerContentObserver(
                android.provider.MediaStore.Images.Media.EXTERNAL_CONTENT_URI,
                true, new ContentObserver(new Handler()) {
                    @Override
                    public void onChange(boolean selfChange) {
                        super.onChange(selfChange);

                        Media media = readFromMediaStore(
                                getApplicationContext(),
                                MediaStore.Images.Media.EXTERNAL_CONTENT_URI);

                        File file = new File(media.file.getPath());
                        Date fileData = new Date(file.lastModified());

                        if (System.currentTimeMillis() - fileData.getTime() > 3000) {

                        } else {

                            if (!media.file.getPath().contains("WhatsApp")) {
                                String saved = media.file.getName();

                                // deduce bitmap before using
                                Bitmap bitmap = BitmapFactory
                                        .decodeFile(media.file.getPath());

                                Intent intent = new Intent();
                                intent.setDataAndType(Uri.fromFile(media.file),
                                        "image/*");
                                PendingIntent pendingIntent = PendingIntent
                                        .getActivity(getApplicationContext(),
                                                0, intent, 0);

                                Notification n = new Notification.Builder(
                                        getApplicationContext())
                                        .setStyle(
                                                new Notification.BigPictureStyle()
                                                        .bigPicture(bitmap))
                                        .setContentTitle(
                                                "New Image File For You")
                                        .setContentText("File Name :" + saved)
                                        .setSmallIcon(R.drawable.alert_icon_1)
                                        .setContentIntent(pendingIntent)
                                        .setAutoCancel(true).build();

                                NotificationManager notificationManager = (NotificationManager) getSystemService(NOTIFICATION_SERVICE);

                                notificationManager.notify(0, n);
                            }
                        }
                    }

                    @Override
                    public void onChange(boolean selfChange, Uri uri) {
                        super.onChange(selfChange, uri);
                    }
                });
        // audio
        getContentResolver().registerContentObserver(
                android.provider.MediaStore.Audio.Media.EXTERNAL_CONTENT_URI,
                true, new ContentObserver(new Handler()) {
                    @Override
                    public void onChange(boolean selfChange) {
                        super.onChange(selfChange);
                        Media media = readFromMediaStore(
                                getApplicationContext(),
                                MediaStore.Audio.Media.EXTERNAL_CONTENT_URI);

                        File file = new File(media.file.getPath());
                        Date fileData = new Date(file.lastModified());

                        if (System.currentTimeMillis() - fileData.getTime() > 3000) {

                        } else {

                            if (!media.file.getPath().contains("WhatsApp")) {

                                String saved = media.file.getName();

                                Bitmap bitmap = BitmapFactory
                                        .decodeFile(media.file.getPath());

                                Intent intent = new Intent();
                                intent.setDataAndType(Uri.fromFile(media.file),
                                        "audio/*");
                                PendingIntent pendingIntent = PendingIntent
                                        .getActivity(getApplicationContext(),
                                                0, intent, 0);

                                Notification n = new Notification.Builder(
                                        getApplicationContext())
                                        .setStyle(
                                                new Notification.BigPictureStyle()
                                                        .bigPicture(null))
                                        .setContentTitle(
                                                "New audio File For You")
                                        .setContentText("File Name :" + saved)
                                        .setSmallIcon(R.drawable.alert_icon_1)
                                        .setContentIntent(pendingIntent)
                                        .setAutoCancel(true).build();

                                NotificationManager notificationManager = (NotificationManager) getSystemService(NOTIFICATION_SERVICE);

                                notificationManager.notify(0, n);
                            }
                        }
                    }

                    @Override
                    public void onChange(boolean selfChange, Uri uri) {
                        super.onChange(selfChange, uri);
                    }
                });
        // video
        getContentResolver().registerContentObserver(
                android.provider.MediaStore.Video.Media.EXTERNAL_CONTENT_URI,
                true, new ContentObserver(new Handler()) {
                    @Override
                    public void onChange(boolean selfChange) {
                        super.onChange(selfChange);
                        Media media = readFromMediaStore(
                                getApplicationContext(),
                                MediaStore.Video.Media.EXTERNAL_CONTENT_URI);

                        File file = new File(media.file.getPath());
                        Date fileData = new Date(file.lastModified());

                        if (System.currentTimeMillis() - fileData.getTime() > 3000) {

                        } else {
                            if (!media.file.getPath().contains("WhatsApp")) {

                                String saved = media.file.getName();

                                Intent intent = new Intent();
                                intent.setDataAndType(Uri.fromFile(media.file),
                                        "video/*");
                                PendingIntent pendingIntent = PendingIntent
                                        .getActivity(getApplicationContext(),
                                                0, intent, 0);

                                Notification n = new Notification.Builder(
                                        getApplicationContext())
                                        .setStyle(
                                                new Notification.BigPictureStyle()
                                                        .bigPicture(null))
                                        .setContentTitle(
                                                "New Video File For You")
                                        .setContentText("File Name :" + saved)
                                        .setSmallIcon(R.drawable.alert_icon_1)
                                        .setContentIntent(pendingIntent)
                                        .setAutoCancel(true).build();

                                NotificationManager notificationManager = (NotificationManager) getSystemService(NOTIFICATION_SERVICE);

                                notificationManager.notify(0, n);
                            }
                        }
                    }

                    @Override
                    public void onChange(boolean selfChange, Uri uri) {
                        super.onChange(selfChange, uri);
                        System.out
                                .println("here is the service change EXTERNAL 1 params"
                                        + " " + uri);
                    }
                });
        return START_STICKY;
    }

    private Long readLastDateFromMediaStore(Context context, Uri uri) {
        Cursor cursor = context.getContentResolver().query(uri, null, null,
                null, "date_added DESC");
        Long dateAdded = (long) -1;
        if (cursor.moveToNext()) {
            dateAdded = cursor.getLong(cursor
                    .getColumnIndexOrThrow(MediaColumns.DATE_ADDED));
        }
        cursor.close();
        return dateAdded;
    }

    private Media readFromMediaStore(Context context, Uri uri) {
        Cursor cursor = context.getContentResolver().query(uri, null, null,
                null, "date_added DESC");
        Media media = null;
        if (cursor.moveToNext()) {
            int dataColumn = cursor.getColumnIndexOrThrow(MediaColumns.DATA);
            String filePath = cursor.getString(dataColumn);
            int mimeTypeColumn = cursor
                    .getColumnIndexOrThrow(MediaColumns.MIME_TYPE);
            String mimeType = cursor.getString(mimeTypeColumn);
            media = new Media(new File(filePath), mimeType);
        }
        cursor.close();
        return media;
    }

    private class Media {
        private File file;

        private String type;

        public Media(File file, String type) {
            this.file = file;
            this.type = type;
        }

        public String getType() {
            return type;
        }

        public File getFile() {
            return file;
        }
    }
}

并且不要忘记取消注册您的观察者onDestroy()。

getContentResolver().unregisterContentObserver(yourObserverObject);