如何创建URL缩短器？

问题：

I want to create a URL shortener service where you can write a long URL into an input field and the service shortens the URL to " http://www.example.org/abcdef ". 我想创建一个URL缩短服务，您可以在其中将长URL写入输入字段，然后该服务将URL缩短为“ http://www.example.org/abcdef ”。

Instead of " abcdef " there can be any other string with six characters containing az, AZ and 0-9 . 除了“ abcdef ”之外，还可以有其他任何六个字符串，包含az, AZ and 0-9 。 That makes 56~57 billion possible strings. 这使得56〜570亿个可能的字符串。

My approach: 我的方法：

I have a database table with three columns: 我有一个包含三列的数据库表：

id, integer, auto-increment id，整数，自动递增
long, string, the long URL the user entered long，字符串，用户输入的长URL
short, string, the shortened URL (or just the six characters) 简短的字符串，缩短的URL（或仅六个字符）

I would then insert the long URL into the table. 然后，我将长网址插入表中。 Then I would select the auto-increment value for " id " and build a hash of it. 然后，我将为“ id ”选择自动增量值，并为其构建一个哈希值。 This hash should then be inserted as " short ". 然后应将此散列插入为“ short ”。 But what sort of hash should I build? 但是我应该建立什么样的哈希？ Hash algorithms like MD5 create too long strings. 像MD5这样的哈希算法创建的字符串太长。 I don't use these algorithms, I think. 我认为我不使用这些算法。 A self-built algorithm will work, too. 自建算法也将起作用。

My idea: 我的点子：

For " http://www.google.de/ " I get the auto-increment id 239472 . 对于“ http://www.google.de/ ”，我得到了自动增量ID 239472 。 Then I do the following steps: 然后，我执行以下步骤：

short = '';
if divisible by 2, add "a"+the result to short
if divisible by 3, add "b"+the result to short
... until I have divisors for a-z and A-Z.

That could be repeated until the number isn't divisible any more. 可以重复进行直到该数字不再可除。 Do you think this is a good approach? 您认为这是个好方法吗？ Do you have a better idea? 你有更好的主意吗？

_{Due to the ongoing interest in this topic, I've published an efficient solution to GitHub , with implementations for JavaScript , PHP , Python and Java .} _{由于对该主题的持续关注，我为GitHub发布了一种有效的解决方案，其中包含JavaScript ， PHP ， Python和Java的实现。} _{Add your solutions if you like :)} _{如果您愿意，请添加您的解决方案:)}