public static File getFile(URL resourceUrl, String description) throws FileNotFoundException {
        Assert.notNull(resourceUrl, "Resource URL must not be null");
        if (!URL_PROTOCOL_FILE.equals(resourceUrl.getProtocol())) {
            throw new FileNotFoundException(
                    description + " cannot be resolved to absolute file path " +
                            "because it does not reside in the file system: " + resourceUrl
            );
        }
        try {
            return new File(toURI(resourceUrl).getSchemeSpecificPart());
        } catch (URISyntaxException ex) {
            // Fallback for URLs that are not valid URIs (should hardly ever happen).
            return new File(resourceUrl.getFile());
        }
    }
Resolve the given resource URL to a {@code java.io.File},
i.e. to a file in the file system.

@param resourceUrl the resource URL to resolve
@param description a description of the original resource that
                   the URL was created for (for example, a class path location)
@return a corresponding File object
@throws FileNotFoundException if the URL cannot be resolved to
                              a file in the file system
src/main/java/spark/utils/ResourceUtils.java