Find a regular expression

"http://www.baidu.com/link?url=N9rqre5k19AvSHy4SZZFS5S7OsMhEOW5XExHhTzaTW"

"

I"m going to match the domain name now because sometimes it"s https or http. I"m going to match http://www.baidu.com/ or https://www.baidu.com/
. How do I write this regular expression

?

^https?://\S+$

upstairs, this seems to be superfluous.

^http(s)?
^http[s ]?
^https?
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