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我正在使用 CursorJoiner 加入 Media.Image 和 Thumbnail 表，以便从特定专辑中选择缩略图，而不使用实际的 SQL。

但是，Media.Image 表和相应的 Thumbnails 表中的数据似乎不匹配。缩略图总是比实际图像少（但我知道缩略图存在于磁盘上）。

我正在使用以下代码：

public ThumbnailSelector(Context context) {
    mContext = context;
}

public List<LocalThumbnail<Integer>> getSqlThumbnailsFromBucket(String bucket) {
    return null;
}

protected Cursor getImageMediaCursor(String bucket) {

    String[] projection = { Media._ID, Media.BUCKET_DISPLAY_NAME };

    String selection = String.format("(%s='%s')", Media.BUCKET_DISPLAY_NAME, bucket);

    Cursor cursor = mContext.getContentResolver().query(Media.EXTERNAL_CONTENT_URI, projection,
    selection, null, Media._ID + " ASC");
    cursor.moveToFirst();

    return cursor;
}

protected Cursor getImageThumbnailCursor() {

    String[] projection = { Thumbnails.IMAGE_ID, Thumbnails.DATA };
    String selection = String.format("%s=%d", Thumbnails.KIND, Thumbnails.MINI_KIND);

    Cursor cursor = mContext.getContentResolver().query(Thumbnails.EXTERNAL_CONTENT_URI,
    projection, selection, null, Thumbnails.IMAGE_ID + " ASC");
    cursor.moveToFirst();

    return cursor;
}

public List<LocalThumbnail<Integer>> getThumbnailsFromBucket(String bucket) {

    List<LocalThumbnail<Integer>> thumbnails = new ArrayList<LocalThumbnail<Integer>>();

    Cursor imageThumbnailCursor = getImageThumbnailCursor();
    Cursor imageMediaCursor = getImageMediaCursor(bucket);

    CursorJoiner joiner = new CursorJoiner(imageMediaCursor, new String[] { Media._ID },
    imageThumbnailCursor, new String[] { Thumbnails.IMAGE_ID });

    int idColumnIndex = imageThumbnailCursor.getColumnIndex(Thumbnails.IMAGE_ID);
    int dataColumnIndex = imageThumbnailCursor.getColumnIndex(Thumbnails.DATA);

    for (CursorJoiner.Result joinerResult : joiner) {
        switch (joinerResult) {
            case RIGHT: {
                break;
            }
            case LEFT: {
                break;
            }
            case BOTH:
            thumbnails.add(new LocalThumbnail<Integer>(imageThumbnailCursor
            .getInt(idColumnIndex), "file://"
            + imageThumbnailCursor.getString(dataColumnIndex)));
            break;
        }
    }

    imageThumbnailCursor.close();
    imageMediaCursor.close();

    return thumbnails;
}

有谁知道为什么会发生这种不匹配？

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