I am using a regular expression to convert plain text URL to clickable links.
@(https?://([-\\w\\.]+)+(:\\d+)?(/([\\w/_\\.-]*(\\?\\S+)?)?)?)@
Ho
http://www.ietf.org/rfc/rfc3986.txt covers URLs and what characters may appear in unencoded form. Given that URLs containing semicolons work properly in browsers, your code should support them.