PHP's algorithm sharing of converting URLs into short URLs

Preface

Many friends may no longer be unfamiliar with short URL services. Now, most places such as Weibo and mobile email reminders have many application models and occupy a certain market. I guess many friends are using it now.

Benefits of short links:

1. Content required;
2. User-friendly;
3. Easy to manage.

The following is the algorithm for short URL conversion using PHP, the code is as follows:

PHP

&lt;?php
//Short URL generation algorithmclass ShortUrl {
  
  // Character table  public static $charset = "0123456789ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz";
 
  public static function encode($url)
  {
    $key = 'abc'; //With salt    $urlhash = md5($key . $url);
    $len = strlen($urlhash);
 
    //Divide the encrypted string into 4 segments, each segment is 4 bytes, and calculate each segment, and a total of four sets of short connections can be generated.    for ($i = 0; $i &lt; 4; $i++) {
      $urlhash_piece = substr($urlhash, $i * $len / 4, $len / 4);
      
      //Bit the bits of the segment and 0x3ffffffff. 0x3ffffffff represents the 30 1s of the binary number, that is, the encryption strings after 30 bits are reset to zero      //Here you need to use hexdec() to convert the hex string into a decimal numerical type, otherwise the operation will be abnormal      $hex = hexdec($urlhash_piece) &amp; 0x3fffffff;
 
      //Fill in the domain name according to your needs      $short_url = "/";
      
      //Generate 6-bit short URL      for ($j = 0; $j &lt; 6; $j++) {
        
        //The obtained value is 61 with 0x000003d and 3d, that is, the maximum coordinate value of charset        $short_url .= self::$charset[$hex &amp; 0x0000003d];
        
        //After the loop is completed, the right shifts hex by 5 digits        $hex = $hex &gt;&gt; 5;
      }
 
      $short_url_list[] = $short_url;
    }
 
    return $short_url_list;
  }
}
 
$url = "/";
$short = ShortUrl::encode($url);
print_r($short);
?&gt;

Usually we can use the first of four groups of URLs.

It should be noted here that this algorithm is irreversible. Therefore, the usual practice is to store the short URL and the corresponding original URL into the database. When accessing, the matching original URL is taken out from the database and jump through 301 or header.

Summarize

The above is the entire content of this article. I hope it will be of some help to everyone's study or work. If you have any questions, you can leave a message to communicate.