Depends on how hard you want to check.
response = nil
begin
response = Net::HTTP.get_response(URI(value1))
rescue
end
response && response.code_type == Net::HTTPOK
Will check that it is a valid URL that points to a working server that honors a GET request without redirecting.
value1 =~ URI.regexp(['http', 'https'])
will just check that it looks like a valid HTTP or HTTPS URL.