├── shorturl_test.go
├── README.md
└── shorturl.go


/shorturl_test.go:
--------------------------------------------------------------------------------
 1 | package shorturl
 2 | 
 3 | import (
 4 | 	"testing"
 5 | )
 6 | 
 7 | func TestShorturl(t *testing.T) {
 8 | 	url := "http://www.example.com?a=1&b=2&c=3&d=4"
 9 | 
10 | 	cb := func(url, keyword string) bool {
11 | 		// todo 查db或缓存判断keyword是否重复
12 | 		return true
13 | 	}
14 | 
15 | 	domain := "http://shorturl.cn"
16 | 	surl := Generator(CHARSET_ALPHANUMERIC, domain, url, cb)
17 | 	if surl == "" {
18 | 		t.Fatalf("Failed: generator shorturl, url[%s]", url)
19 | 	}
20 | }
21 | 


--------------------------------------------------------------------------------
/README.md:
--------------------------------------------------------------------------------
 1 | # shorturl
 2 | 	短链接生成算法
 3 | 
 4 | ## Installation
 5 | 
 6 | 	$ go get github.com/kaimixu/shorturl
 7 | 	
 8 | ## Usage
 9 | 
10 | 	package main
11 | 
12 | 	import (
13 | 		"fmt"			
14 | 		"github.com/kaimixu/shorturl"
15 | 	)
16 | 
17 | 	func main() {
18 | 		url := "http://www.example.com?a=1&b=2&c=3&d=4"
19 | 
20 | 		cb := func(url, keyword string) bool {
21 | 			// todo 查db或缓存判断keyword是否重复
22 | 		return true
23 | 		}
24 | 
25 | 		domain := "http://shorturl.cn"
26 | 		surl := shorturl.Generator(shorturl.CHARSET_ALPHANUMERIC, domain, url, cb)
27 | 		fmt.Println(surl)
28 | 	}
29 | 


--------------------------------------------------------------------------------
/shorturl.go:
--------------------------------------------------------------------------------
 1 | package shorturl
 2 | 
 3 | import (
 4 | 	"fmt"
 5 | 	"strconv"
 6 | 	"crypto/md5"
 7 | 	"strings"
 8 | )
 9 | 
10 | const (
11 | 	CHARSET_ALPHANUMERIC = iota
12 | 	CHARSET_RANDOM_ALPHANUMERIC
13 | )
14 | 
15 | func getCharset(t int) string {
16 | 	switch t {
17 | 	case CHARSET_ALPHANUMERIC:
18 | 		return "0123456789abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ"
19 | 	case CHARSET_RANDOM_ALPHANUMERIC:
20 | 		return "A0a12B3b4CDc56Ede7FGf8Hg9IhJKiLjkMNlmOPnQRopqrSstTuvUVwxWXyYzZ"
21 | 	default:
22 | 		panic("invalid charset type t:" + strconv.Itoa(t))
23 | 	}
24 | }
25 | 
26 | // 生成6字符短key
27 | // 根据url生成32字符的签名，将其分成4段，每段8位字符
28 | // 循环处理4段8位字符，将每段转换成16进制与0x3FFFFFFF进行逻辑与操作，得到30位的无符号数
29 | // 将30位数分成6段，依次得到6个0-61的数字索引查字符集表获得6位字符串
30 | func generator6(charset ,url, hexMd5 string,  sectionNum int, cb func(url, keyword string) bool) string {
31 | 	for i := 0; i < sectionNum; i++ {
32 | 		sectionHex := hexMd5[i*8:8+i*8]
33 | 		bits, _ := strconv.ParseUint(sectionHex, 16, 32)
34 | 		bits = bits & 0x3FFFFFFF
35 | 
36 | 		keyword := ""
37 | 		for j := 0; j < 6; j++ {
38 | 			idx := bits & 0x3D
39 | 			keyword = keyword + string(charset[idx])
40 | 			bits = bits >> 5
41 | 		}
42 | 
43 | 		if cb(url, keyword) {
44 | 			return keyword
45 | 		}
46 | 	}
47 | 
48 | 	return ""
49 | }
50 | 
51 | // 生成8字符短key
52 | func generator8(charset, url, hexMd5 string,  sectionNum int, cb func(url, keyword string) bool) string {
53 | 	for i := 0; i < sectionNum; i++ {
54 | 		sectionHex := hexMd5[i*8:i*8+8]
55 | 		bits, _ := strconv.ParseUint(sectionHex, 16, 32)
56 | 		bits = bits & 0xFFFFFFFF
57 | 
58 | 		keyword := ""
59 | 		for j := 0; j < 8; j++ {
60 | 			idx := bits & 0x3D
61 | 			keyword = keyword + string(charset[idx])
62 | 			bits = bits >> 4
63 | 		}
64 | 
65 | 		if cb(url, keyword) {
66 | 			return keyword
67 | 		}
68 | 	}
69 | 
70 | 	return ""
71 | }
72 | 
73 | // 生成6-8字符的短链接，参数t表示字符集类型，回调函数(cb)用于检测短链接是否重复
74 | // 起初生成6位的短链接，当四组6位短链接都重复时，再生成8位的短链接
75 | func Generator(t int, domain string, url string, cb func(url, keyword string) bool) (shorturl string) {
76 | 	if domain == "" || url == "" || cb == nil {
77 | 		return
78 | 	}
79 | 
80 | 	charset := getCharset(t)
81 | 	hexMd5 := fmt.Sprintf("%x", md5.Sum([]byte(url)))
82 | 	sections := len(hexMd5)/8
83 | 
84 | 	keyword := generator6(charset, url, hexMd5, sections, cb)
85 | 	if keyword == "" {
86 | 		keyword = generator8(charset, url, hexMd5, sections, cb)
87 | 		if keyword == "" {
88 | 			return ""
89 | 		}
90 | 	}
91 | 
92 | 	if strings.HasSuffix(domain, "/") {
93 | 		shorturl = domain + keyword
94 | 	}else {
95 | 		shorturl = domain + "/" + keyword
96 | 	}
97 | 	return
98 | }
99 | 


--------------------------------------------------------------------------------