生成随机字符串

package common

import (
    "math/rand"
    "time"
)

const LowerString = "abcdefghijklmnopqrstuvwxyz"
const UpperString = "ABCDEFGHIJKLMNOPQRSTUVWXYZ"
const DigitString = "0123456789"
const PunctString = "~!@#$%^&*()_+-="

func init() {
    rand.Seed(time.Now().UTC().UnixNano())
}

func RandString(size int, include string) string {
    all := include

    lenAll := len(all)

    buf := make([]byte, size)
    for i := 0; i < size; i++ {
        b := all[rand.Intn(lenAll)]
        buf[i] = b
    }
    return string(buf)
}