MIME type strings are ubiquitous on the Internet, yet the Java platform still
has no direct support for parsing, constructing, comparing, or otherwise
manipulating them.  Several subsystems make use of MIME types, including image
I/O, drag-and-drop, printing, and various URL content handlers, and therefore
include their own custom code for handling MIME type strings.  At least one new
feature in Dolphin (4313887: New I/O: Improved filesystem interface) may also
support MIME types in some way.

In order to unify the handling of MIME types in the platform, and to make it
possible for developers to process MIME types without resorting to ad-hoc code,
we should define a simple class (or small number of classes) that implement the
relevant RFCs as closely as possible and support the basic operations of
parsing, constructing, and comparing MIME type strings.  Optionally, we could
also provide access to users' .mime.types and .mailcap files, or to their
equivalents on other platforms.