66 lines
1.8 KiB
Go
66 lines
1.8 KiB
Go
package uuid
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import (
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"unsafe"
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"github.com/google/uuid"
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)
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const (
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letters = "abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ1234567890"
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MIN_LENGTH = 2 // 最小长度为2的原因是Go中整型长度最大为64位，而UUID v4是128位长，所以最小长度为2。
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MAX_LENGTH = 128
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)
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// 将一个字节拆分成8个比特位，并以一个8位长字节数组输出。
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func breakByte(b byte) []byte {
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bytes := make([]byte, 8)
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for i := byte(0); i < 8; i++ {
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mask := byte(0x1) << (7 - i)
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bytes[i] = (b & mask) >> (7 - i)
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}
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return bytes
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}
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// 根据UUID v4生成一个指定长度的短UUID字符串。
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func ShortUUID(length uint) string {
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var uuidLength uint
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if length < MIN_LENGTH {
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uuidLength = MIN_LENGTH
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} else if length > MAX_LENGTH {
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uuidLength = MAX_LENGTH
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} else {
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uuidLength = length
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}
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// UUID是一个16字节长的字节数组，每个字节都可以拆分成8个比特位，共128比特位。
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newUUID := uuid.New()
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uuidBits := make([]byte, 0)
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for _, b := range newUUID[:] {
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uuidBits = append(uuidBits, breakByte(b)...)
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}
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var partitionLength uint = 0
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if 128%uuidLength == 0 {
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partitionLength = 128 / uuidLength
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} else {
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partitionLength = 128/uuidLength + 1
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}
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var paritionedUUID = make([][]byte, uuidLength)
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for i := uint(0); i < uuidLength; i++ {
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if i != uuidLength-1 {
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paritionedUUID[i] = uuidBits[i*partitionLength : (i+1)*partitionLength]
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} else {
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paritionedUUID[i] = uuidBits[i*partitionLength:]
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}
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}
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result := make([]byte, uuidLength)
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for i := uint(0); i < uuidLength; i++ {
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var assembledRune uint64 = 0
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for j := uint(0); j < uint(len(paritionedUUID[i])); j++ {
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assembledRune |= uint64(paritionedUUID[i][j]) << (partitionLength - j - 1)
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}
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result[i] = letters[assembledRune%uint64(len(letters))]
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}
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return *(*string)(unsafe.Pointer(&result))
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}
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