您可以散列整个URL，但如果您只想缩短id，请按照marcel的建议进行。我写了这个Python实现:

https://gist.github.com/778542

为什么要使用哈希呢?

您只需将自动递增值简单地转换为字母数字值。你可以通过使用一些基数转换很容易做到这一点。假设您的字符空间(a-z, a-z, 0-9等)有62个字符，将id转换为以40为基数的数字并使用这些字符作为数字。

alphabet = map(chr, range(97,123)+range(65,91)) + map(str,range(0,10))

def lookup(k, a=alphabet):
    if type(k) == int:
        return a[k]
    elif type(k) == str:
        return a.index(k)


def encode(i, a=alphabet):
    '''Takes an integer and returns it in the given base with mappings for upper/lower case letters and numbers 0-9.'''
    try:
        i = int(i)
    except Exception:
        raise TypeError("Input must be an integer.")

    def incode(i=i, p=1, a=a):
        # Here to protect p.                                                                                                                                                                                                                
        if i <= 61:
            return lookup(i)

        else:
            pval = pow(62,p)
            nval = i/pval
            remainder = i % pval
            if nval <= 61:
                return lookup(nval) + incode(i % pval)
            else:
                return incode(i, p+1)

    return incode()



def decode(s, a=alphabet):
    '''Takes a base 62 string in our alphabet and returns it in base10.'''
    try:
        s = str(s)
    except Exception:
        raise TypeError("Input must be a string.")

    return sum([lookup(i) * pow(62,p) for p,i in enumerate(list(reversed(s)))])a

这是我的版本，给任何需要的人。

这是我的PHP 5类。

<?php
class Bijective
{
    public $dictionary = "abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ0123456789";

    public function __construct()
    {
        $this->dictionary = str_split($this->dictionary);
    }

    public function encode($i)
    {
        if ($i == 0)
        return $this->dictionary[0];

        $result = '';
        $base = count($this->dictionary);

        while ($i > 0)
        {
            $result[] = $this->dictionary[($i % $base)];
            $i = floor($i / $base);
        }

        $result = array_reverse($result);

        return join("", $result);
    }

    public function decode($input)
    {
        $i = 0;
        $base = count($this->dictionary);

        $input = str_split($input);

        foreach($input as $char)
        {
            $pos = array_search($char, $this->dictionary);

            $i = $i * $base + $pos;
        }

        return $i;
    }
}

public class TinyUrl {
    
        private final String characterMap = "abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ0123456789";
        private final int charBase = characterMap.length();
    
        public String covertToCharacter(int num){
            StringBuilder sb = new StringBuilder();
    
            while (num > 0){
                sb.append(characterMap.charAt(num % charBase));
                num /= charBase;
            }
    
            return sb.reverse().toString();
        }
    
        public int covertToInteger(String str){
            int num = 0;
            for(int i = 0 ; i< str.length(); i++)
                num += characterMap.indexOf(str.charAt(i)) * Math.pow(charBase , (str.length() - (i + 1)));
    
            return num;
        }
}
    
class TinyUrlTest{
    
    public static void main(String[] args) {
        TinyUrl tinyUrl = new TinyUrl();
        int num = 122312215;
        String url = tinyUrl.covertToCharacter(num);
        System.out.println("Tiny url:  " + url);
        System.out.println("Id: " + tinyUrl.covertToInteger(url));
    }
}

这是一个不错的PHP URL编码函数…

// From http://snipplr.com/view/22246/base62-encode--decode/
private function base_encode($val, $base=62, $chars='0123456789abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ') {
    $str = '';
    do {
        $i = fmod($val, $base);
        $str = $chars[$i] . $str;
        $val = ($val - $i) / $base;
    } while($val > 0);
    return $str;
}