问题
The closest thing I could find was System.Net.Mime.MediaTypeNames but that doesn't seem to have everything (like json) since it seems to be more focused around email attachments.
回答1:
An enum doesn't make much sense. MIME types are open-ended. That is, the list is not finite: new types are added from time to time.
See RFC4288: Media Type Specifications and Registration Procedures
回答2:
IANA's database is most likely to be complete, but you would need to parse those pages to get a flat list.
There is also the mime.types file that comes with Apache which seems to have been derived from the said list.
来源：https://stackoverflow.com/questions/1015892/is-there-an-enum-for-the-contenttype-property-on-a-httpwebresponse-text-plain