如何判斷URL格式是否符合規(guī)范？

    <%
    function checkisUrl(tmpString)
    dim c,i
    checkisUrl = true
    tmpString=Lcase(trim(tmpString))
    if left(tmpString,7)<>"http://" then tmpString="http://"&tmpString
    for i = 8 to Len(checkisUrl)
    c = Lcase(Mid(tmpString, i, 1))
    if InStr("abcdefghijklmnopqrstuvwxyz_-./\", c) <= 0 and not IsNumeric(c) then
    checkisUrl = false
    exit function
    end if
    next
    if Left(tmpString, 1) = "." or Right(tmpString, 1) = "." then
    checkisUrl = false
    exit function
    end if
    if InStr(tmpString, ".") <= 0 then
    checkisUrl = false
    response.Write "f3"
    exit function
    end if
    if InStr(checkisUrl, "..") > 0 then
    checkisUrl = false
    end if
    end function
    %>
    <%
    if checkisUrl(request("u"))=true then
    %>恭喜,你的URL通過!
    <%
    else
    %>對不起,你的URL不合乎規(guī)范,請重新檢查!
    <%end if%>