This interface defines a single method that is called to obtain the MIME type of a file based on the name of a file. The fileNameMap field of the URLConnection class refers to an object that implements this interface. The filename-to-file-type map it implements is used by the static URLConnection.guessContentTypeFromName() method.
public abstract interface FileNameMap { // Public Instance Methods public abstract String getContentTypeFor(String fileName); }
URLConnection.fileNameMap