android - Androidで新しい写真を聞く方法は?

Question

画像のダウンロード、新しい画像のキャプチャ、他のアプリによる画像のダウンロードなど、あらゆるソースからの新しい画像をリッスンする必要があります。新しい写真がギャラリーに追加されるたびにイベントをトリガーするリスナーはありますか? 私は2日間探していました。しっかりしたものは取れませんでした。

について読みまし FileObserverたが、役に立ちますか?

Answer 1

new photos arrives to gallery

means it has been added to the MediaStore.

First of all, FileOberver is a memory-killer approach. Consider a high volume of files. Rather ContentObserver seems a far better approach.

getContentResolver().registerContentObserver(android.provider.MediaStore.Images.Media.INTERNAL_CONTENT_URI, true, 
        new ContentObserver(new Handler()) {
            @Override
            public void onChange(boolean selfChange) {
                Log.d("your_tag","Internal Media has been changed");
                super.onChange(selfChange);
                Long timestamp = readLastDateFromMediaStore(context, MediaStore.Images.Media.INTERNAL_CONTENT_URI);
                // comapare with your stored last value and do what you need to do

            }
        }
    );
getContentResolver().registerContentObserver(android.provider.MediaStore.Images.Media.EXTERNAL_CONTENT_URI, true, 
    new ContentObserver(new Handler()) {
        @Override
        public void onChange(boolean selfChange) {
            Log.d("your_tag","External Media has been changed");
            super.onChange(selfChange);

            Long timestamp = readLastDateFromMediaStore(context, MediaStore.Images.Media.EXTERNAL_CONTENT_URI);
            // comapare with your stored last value and do what you need to do
        }
    }
);

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

Probably a good idea to do this in a service (ever running)! You will also need to unregister in the onDestroy()

Warning: This only tells you when the MediaStore has been changed, it does not tellly anything specific about addition/deletion. For this, you may have to query the MediaStore to detect any change from your previous database or something.