接入USB，通过监听系统数据库变化，每次变化，判断新增文件是否是视频文件，如果是视频文件则在recyclerView中显示出来，即使跳转到其他页面，回到本页面，会把所有变化的新增视频文件展示出来，java代码实现

首先，我们需要在AndroidManifest.xml文件中添加文件读写权限：

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

接着，我们需要创建一个广播接收器来监听系统数据库变化：

public class MediaReceiver extends BroadcastReceiver {

    @Override
    public void onReceive(Context context, Intent intent) {
        String action = intent.getAction();
        if (action != null && action.equals(Intent.ACTION_MEDIA_SCANNER_FINISHED)) {
            // 扫描完成，可以开始获取媒体文件
            List<MediaFile> mediaFiles = getMediaFiles(context);
            // 将媒体文件展示在RecyclerView中
            updateRecyclerView(mediaFiles);
        }
    }

    private List<MediaFile> getMediaFiles(Context context) {
        List<MediaFile> mediaFiles = new ArrayList<>();
        ContentResolver contentResolver = context.getContentResolver();
        // 查询媒体库中的视频文件
        Cursor cursor = contentResolver.query(MediaStore.Video.Media.EXTERNAL_CONTENT_URI, null, null, null, null);
        if (cursor != null) {
            while (cursor.moveToNext()) {
                int id = cursor.getInt(cursor.getColumnIndex(MediaStore.Video.Media._ID));
                String title = cursor.getString(cursor.getColumnIndex(MediaStore.Video.Media.TITLE));
                String path = cursor.getString(cursor.getColumnIndex(MediaStore.Video.Media.DATA));
                long duration = cursor.getLong(cursor.getColumnIndex(MediaStore.Video.Media.DURATION));
                long size = cursor.getLong(cursor.getColumnIndex(MediaStore.Video.Media.SIZE));
                String mimeType = cursor.getString(cursor.getColumnIndex(MediaStore.Video.Media.MIME_TYPE));
                // 判断文件是否存在
                File file = new File(path);
                if (file.exists()) {
                    // 将媒体文件添加到列表中
                    MediaFile mediaFile = new MediaFile(id, title, path, duration, size, mimeType);
                    mediaFiles.add(mediaFile);
                }
            }
            cursor.close();
        }
        return mediaFiles;
    }

    private void updateRecyclerView(List<MediaFile> mediaFiles) {
        // 更新RecyclerView中的数据
        // ...
    }
}

接下来，在Activity中注册广播接收器：

private MediaReceiver mediaReceiver;

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

    // 注册广播接收器
    mediaReceiver = new MediaReceiver();
    IntentFilter intentFilter = new IntentFilter();
    intentFilter.addAction(Intent.ACTION_MEDIA_SCANNER_FINISHED);
    registerReceiver(mediaReceiver, intentFilter);
}

@Override
protected void onDestroy() {
    super.onDestroy();
    // 注销广播接收器
    unregisterReceiver(mediaReceiver);
}

最后，在RecyclerView的Adapter中更新数据：

public class MediaAdapter extends RecyclerView.Adapter<MediaAdapter.ViewHolder> {

    private List<MediaFile> mediaFiles;

    public MediaAdapter(List<MediaFile> mediaFiles) {
        this.mediaFiles = mediaFiles;
    }

    @Override
    public ViewHolder onCreateViewHolder(ViewGroup parent, int viewType) {
        View view = LayoutInflater.from(parent.getContext()).inflate(R.layout.item_media, parent, false);
        return new ViewHolder(view);
    }

    @Override
    public void onBindViewHolder(ViewHolder holder, int position) {
        MediaFile mediaFile = mediaFiles.get(position);
        holder.titleTextView.setText(mediaFile.getTitle());
        holder.durationTextView.setText(formatDuration(mediaFile.getDuration()));
    }

    @Override
    public int getItemCount() {
        return mediaFiles.size();
    }

    public void updateData(List<MediaFile> mediaFiles) {
        this.mediaFiles = mediaFiles;
        notifyDataSetChanged();
    }

    public static class ViewHolder extends RecyclerView.ViewHolder {

        private TextView titleTextView;
        private TextView durationTextView;

        public ViewHolder(View itemView) {
            super(itemView);
            titleTextView = itemView.findViewById(R.id.titleTextView);
            durationTextView = itemView.findViewById(R.id.durationTextView);
        }
    }

    private String formatDuration(long duration) {
        long minutes = TimeUnit.MILLISECONDS.toMinutes(duration);
        long seconds = TimeUnit.MILLISECONDS.toSeconds(duration) - TimeUnit.MINUTES.toSeconds(minutes);
        return String.format(Locale.getDefault(), "%d:%02d", minutes, seconds);
    }
}

这样，每次新增视频文件时，广播接收器会接收到系统数据库变化的通知，然后获取新增的媒体文件并展示在RecyclerView中。如果跳转到其他页面再回来，也会重新获取媒体文件并展示在RecyclerView中。