go随机生成token

const (
    defaultTokenLen int = 16
)
func GenerateToken() string {
    rand.Seed(time.Now().UnixNano())
    runes := []rune("abcdefghijklmnopqrstuvwxyz0123456789")

    b := make([]rune, defaultTokenLen)
    for i := range b {
        b[i] = runes[rand.Intn(len(runes))]
    }
    return string(b)
}