44 lines
1.1 KiB
Go
44 lines
1.1 KiB
Go
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package utils
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import (
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"crypto/md5"
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"fmt"
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"strconv"
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)
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const charset = "A0a12B3b4CDc56Ede7FGf8Hg9IhJKiLjkMNlmOPnQRopqrSstTuvUVwxWXyYzZ"
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func generateCharset(url, hexMd5 string, len, sectionNum int, cb func(url, keyword string) bool) string {
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for i := 0; i < sectionNum; i++ {
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sectionHex := hexMd5[i*8 : 8+i*8]
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bits, _ := strconv.ParseUint(sectionHex, 16, 32)
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bits = bits & 0x3FFFFFFF
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keyword := ""
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for j := 0; j < len; j++ {
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idx := bits & 0x3D
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keyword = keyword + string(charset[idx])
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bits = bits >> 5
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}
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if cb(url, keyword) {
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return keyword
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}
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}
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return ""
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}
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// 起初生成6位的短码，当四组6位短码都重复时，再生成8位的短码，因此总共会有8个短码供你选择。
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func GenerateShortUrl(url string, cb func(url, keyword string) bool) string {
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if url == "" || cb == nil {
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return ""
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}
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hexMd5 := fmt.Sprintf("%x", md5.Sum([]byte(url)))
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sections := len(hexMd5) / 8
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keyword := generateCharset(url, hexMd5, 6, sections, cb)
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if keyword == "" {
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return generateCharset(url, hexMd5, 8, sections, cb)
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}
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return keyword
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}
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