// 404
            throw responseManager.new404("Thumbnail for " + form.docId + " is not found.");
        }

        final File thumbnailFile = thumbnailManager.getThumbnailFile(doc);
        if (thumbnailFile == null) {
            if (fessConfig.isThumbnailEnabled()) {
                thumbnailManager.offer(doc);
            }
            // 404

            buf.append('_').append(Integer.toString(hash)).append('/');
        }
        buf.append(docid).append('.').append(imageExtention);
        return buf.toString();
    }

    public File getThumbnailFile(final Map<String, Object> docMap) {
        final String thumbnailPath = getImageFilename(docMap);
        if (StringUtil.isNotBlank(thumbnailPath)) {
            final File file = new File(baseDir, thumbnailPath);