Get content type from file extension

gistfile1.txt

		public string GetContentType(string filename)
		{
			string mimeType = "application/unknown";

			string extension = Path.GetExtension(filename);

			if (string.IsNullOrWhiteSpace(extension))
			{
				return mimeType;
			}

			RegistryKey regKey = Registry.ClassesRoot.OpenSubKey(extension.ToLower());

			if (regKey != null)
			{
				object contentType = regKey.GetValue("Content Type");

				if (contentType != null)
				{
					mimeType = contentType.ToString();
				}
			}

			return mimeType;
		}