URLバリデート正規表現
(https?|ftp)(:\/\/[-_.!~*\'()a-zA-Z0-9;\/?:\@&=+\$,%#]+)
正確には、
\b(?:https?|shttp)://(?:(?:[-_.!~*'()a-zA-Z0-9;:&=+$,]|%[0-9A-Fa-f ][0-9A-Fa-f])*@)?(?:(?:[a-zA-Z0-9](?:[-a-zA-Z0-9]*[a-zA-Z0-9])?\.) *[a-zA-Z](?:[-a-zA-Z0-9]*[a-zA-Z0-9])?\.?|[0-9]+\.[0-9]+\.[0-9]+\. [0-9]+)(?::[0-9]*)?(?:/(?:[-_.!~*'()a-zA-Z0-9:@&=+$,]|%[0-9A-Fa-f] [0-9A-Fa-f])*(?:;(?:[-_.!~*'()a-zA-Z0-9:@&=+$,]|%[0-9A-Fa-f][0-9A- Fa-f])*)*(?:/(?:[-_.!~*'()a-zA-Z0-9:@&=+$,]|%[0-9A-Fa-f][0-9A-Fa-f ])*(?:;(?:[-_.!~*'()a-zA-Z0-9:@&=+$,]|%[0-9A-Fa-f][0-9A-Fa-f])*)*) *)?(?:\?(?:[-_.!~*'()a-zA-Z0-9;/?:@&=+$,]|%[0-9A-Fa-f][0-9A-Fa-f]) *)?(?:#(?:[-_.!~*'()a-zA-Z0-9;/?:@&=+$,]|%[0-9A-Fa-f][0-9A-Fa-f])* )?
のようです。すげぇ（笑
正規表現：正しいＵＲＬかどうか調べる - phpspot
http://phpspot.net/php/pg%90%B3%8BK%95%5C%8C%BB%81F%90%B3%82%B5%82%A2%82t%82q%82k%82%A9%82%C7%82%A4%82%A9%92%B2%82%D7%82%E9.html
