golang 隨機數/域名校驗

//隨機數生成要用到的
const letterBytes = "1234567890abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ"
const (
   letterIdxBits = 6
   letterIdxMask = 1<<letterIdxBits - 1
   letterIdxMax  = 63 / letterIdxBits
)

//domain check
func DomainCheck(domain string) bool {
   var match bool
   //支持以http://或者https://開頭而且域名中間有/的狀況
   IsLine := "^((http://)|(https://))?([a-zA-Z0-9]([a-zA-Z0-9\\-]{0,61}[a-zA-Z0-9])?\\.)+[a-zA-Z]{2,6}(/)"
   //支持以http://或者https://開頭而且域名中間沒有/的狀況
   NotLine := "^((http://)|(https://))?([a-zA-Z0-9]([a-zA-Z0-9\\-]{0,61}[a-zA-Z0-9])?\\.)+[a-zA-Z]{2,6}"
   match, _ = regexp.MatchString(IsLine, domain)
   if !match {
      match, _ = regexp.MatchString(NotLine, domain)
   }
   return match
}

//推廣id隨機生成()
func RandStringBytesMaskImprSrc(n int) string {
   var src = rand.NewSource(time.Now().UnixNano())
   b := make([]byte, n)
   for i, cache, remain := n-1, src.Int63(), letterIdxMax; i >= 0; {
      if remain == 0 {
         cache, remain = src.Int63(), letterIdxMax
      }
      if idx := int(cache & letterIdxMask); idx < len(letterBytes) {
         b[i] = letterBytes[idx]
         i--
      }
      cache >>= letterIdxBits
      remain--
   }
   return string(b)
}