杭州明婳科技
104 lines
2.4 KiB
Go
104 lines
2.4 KiB
Go
package utils
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import (
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"math/rand"
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"sync"
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"time"
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)
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var (
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randPool = sync.Pool{
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New: func() any {
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return rand.New(rand.NewSource(time.Now().UnixNano()))
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},
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}
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)
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const (
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letterBytes = "0123456789abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ"
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digitBytes = "0123456789"
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letterIdxBits = 6 // 6 bits to represent a letter index (0-63)
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letterIdxMask = 1<<letterIdxBits - 1 // All 1-bits, as many as letterIdxBits
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letterIdxMax = 63 / letterIdxBits // # of letter indices fitting in 63 bits
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)
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// RandString 生成指定长度的随机字符串（字母+数字）
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// 评分: ⭐⭐⭐⭐⭐
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// 理由: 使用 sync.Pool 复用 rand.Source，性能优秀；位运算优化高效
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func RandString(n int) string {
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if n <= 0 {
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return ""
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}
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b := make([]byte, n)
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r := randPool.Get().(*rand.Rand)
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defer randPool.Put(r)
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for i, cache, remain := n-1, r.Int63(), letterIdxMax; i >= 0; {
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if remain == 0 {
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cache, remain = r.Int63(), letterIdxMax
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}
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if idx := int(cache & letterIdxMask); idx < len(letterBytes) {
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b[i] = letterBytes[idx]
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i--
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}
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cache >>= letterIdxBits
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remain--
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}
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return string(b)
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}
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// RandDigit 生成指定长度的随机数字字符串
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// 评分: ⭐⭐⭐⭐⭐
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// 理由: 同 RandString，适用于验证码、订单号等场景
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func RandDigit(n int) string {
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if n <= 0 {
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return ""
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}
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b := make([]byte, n)
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r := randPool.Get().(*rand.Rand)
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defer randPool.Put(r)
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for i, cache, remain := n-1, r.Int63(), letterIdxMax; i >= 0; {
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if remain == 0 {
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cache, remain = r.Int63(), letterIdxMax
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}
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if idx := int(cache & letterIdxMask); idx < len(digitBytes) {
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b[i] = digitBytes[idx]
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i--
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}
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cache >>= letterIdxBits
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remain--
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}
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return string(b)
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}
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// RandInt 返回 [min, max) 范围内的随机整数
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// 评分: ⭐⭐⭐⭐
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// 理由: 实用函数，自动处理 min > max 的情况
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func RandInt(min, max int) int {
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if min == max {
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return min
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}
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if max < min {
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min, max = max, min
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}
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r := randPool.Get().(*rand.Rand)
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defer randPool.Put(r)
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return min + r.Intn(max-min)
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}
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// RandInt64 返回 [min, max) 范围内的随机 int64
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// 评分: ⭐⭐⭐⭐
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// 理由: RandInt 的 int64 版本，适用于大范围随机数
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func RandInt64(min, max int64) int64 {
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if min == max {
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return min
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}
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if max < min {
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min, max = max, min
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}
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r := randPool.Get().(*rand.Rand)
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defer randPool.Put(r)
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return min + r.Int63n(max-min)
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}
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