go get github.com/mattheath/base62

package main
 
import (
	"fmt"
	"github.com/mattheath/base62"
)
 
func main() {
	// 編碼
	encoded := base62.Encode(123456789) // 輸出 "7BSj"
 
	// 解碼
	decoded, _ := base62.Decode("7BSj") // 輸出 123456789
 
	fmt.Println(encoded, decoded)
}

package base62
 
import (
	"errors"
	"math"
)
 
const (
	base         = 62
	characterSet = "0123456789ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz"
)
 
// Encode 將 uint64 數(shù)字轉(zhuǎn)換為 Base62 字符串
func Encode(num uint64) string {
	if num == 0 {
		return string(characterSet[0])
	}
 
	var result []byte
	for num > 0 {
		remainder := num % base
		result = append(result, characterSet[remainder])
		num = num / base
	}
 
	// 反轉(zhuǎn)字節(jié)順序
	for i, j := 0, len(result)-1; i < j; i, j = i+1, j-1 {
		result[i], result[j] = result[j], result[i]
	}
 
	return string(result)
}
 
// Decode 將 Base62 字符串解析為 uint64
func Decode(str string) (uint64, error) {
	var num uint64
	for _, char := range str {
		pos := findCharIndex(char)
		if pos == -1 {
			return 0, errors.New("invalid character")
		}
		if num > (math.MaxUint64-uint64(pos))/base {
			return 0, errors.New("value out of range")
		}
		num = num*base + uint64(pos)
	}
	return num, nil
}
 
// 查找字符在字符集中的位置
func findCharIndex(c rune) int {
	for i, ch := range characterSet {
		if ch == c {
			return i
		}
	}
	return -1
}

if num > (math.MaxUint64-uint64(pos))/base {
    return 0, errors.New("value out of range")
}

func EncodeOptimized(num uint64) string {
	if num == 0 {
		return "0"
	}
 
	// 預(yù)分配足夠空間（uint64最大Base62長(zhǎng)度為11）
	buf := make([]byte, 0, 11)
	for num > 0 {
		remainder := num % base
		buf = append(buf, characterSet[remainder])
		num /= base
	}
 
	// 反向填充結(jié)果
	res := make([]byte, len(buf))
	for i, j := 0, len(buf)-1; j >= 0; i, j = i+1, j-1 {
		res[i] = buf[j]
	}
	return string(res)
}

var (
	cache     = make(map[uint64]string)
	cacheLock sync.RWMutex
)
 
func GetCachedEncoding(num uint64) string {
	cacheLock.RLock()
	if val, exists := cache[num]; exists {
		cacheLock.RUnlock()
		return val
	}
	cacheLock.RUnlock()
 
	encoded := Encode(num)
 
	cacheLock.Lock()
	cache[num] = encoded
	cacheLock.Unlock()
 
	return encoded
}

// 使用雪花算法生成ID
func GenerateSnowflakeID() uint64 {
	// 實(shí)現(xiàn)略...
}
 
// 生成短鏈
shortCode := base62.Encode(GenerateSnowflakeID())