php获取随机字符串的几种方法

方法一:shuffle函数（打乱数组）和mt_rand函数（生成随机数，比rand速度快四倍）

 /**
  * 获得随机字符串
  * @param $len             需要的长度
  * @param $special        是否需要特殊符号
  * @return string       返回随机字符串
  */
 function getRandomStr($len, $special=true){
     $chars = array(
         "a", "b", "c", "d", "e", "f", "g", "h", "i", "j", "k",
         "l", "m", "n", "o", "p", "q", "r", "s", "t", "u", "v",
         "w", "x", "y", "z", "A", "B", "C", "D", "E", "F", "G",
         "H", "I", "J", "K", "L", "M", "N", "O", "P", "Q", "R",
         "S", "T", "U", "V", "W", "X", "Y", "Z", "0", "1", "2",
         "3", "4", "5", "6", "7", "8", "9"
     );

     if($special){
         $chars = array_merge($chars, array(
             "!", "@", "#", "$", "?", "|", "{", "/", ":", ";",
             "%", "^", "&", "*", "(", ")", "-", "_", "[", "]",
             "}", "<", ">", "~", "+", "=", ",", "."
         ));
     }

     $charsLen = count($chars) - 1;
     shuffle($chars);                            //打乱数组顺序
     $str = '';
     for($i=0; $i<$len; $i++){
         $str .= $chars[mt_rand(0, $charsLen)];    //随机取出一位
     }
     return $str;
 }

方法二、str_shuffle函数（打乱字符串顺序）和mt_rand函数

 //取随机10位字符串
 $strs="QWERTYUIOPASDFGHJKLZXCVBNM1234567890qwertyuiopasdfghjklzxcvbnm";
 $name=substr(str_shuffle($strs),mt_rand(0,strlen($strs)-11),10);
 echo $name;

方法三、md5(),uniqid(),microtime()生成唯一的32位字符串

$uniqid = md5(uniqid(microtime(true),true));
//microtime(true)  返回系统当前时间戳的毫秒数

其他方法:

 /**
      * 方法一：获取随机字符串
      * @param number $length 长度
      * @param string $type 类型
      * @param number $convert 转换大小写
      * @return string 随机字符串
      */
     function random($length = 6, $type = 'string', $convert = 0)
     {
         $config = array(
             'number' => '1234567890',
             'letter' => 'abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ',
             'string' => 'abcdefghjkmnpqrstuvwxyzABCDEFGHJKMNPQRSTUVWXYZ23456789',
             'all' => 'abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ1234567890'
         );

         if (!isset($config[$type]))
             $type = 'string';
         $string = $config[$type];

         $code = '';
         $strlen = strlen($string) - 1;
         for ($i = 0; $i < $length; $i++) {
             $code .= $string{mt_rand(0, $strlen)};
         }
         if (!empty($convert)) {
             $code = ($convert > 0) ? strtoupper($code) : strtolower($code);
         }
         return $code;
     }

     /**
      * 方法二：获取随机字符串
      * @param int $randLength 长度
      * @param int $addtime 是否加入当前时间戳
      * @param int $includenumber 是否包含数字
      * @return string
      */
     function rand_str($randLength = 6, $addtime = 1, $includenumber = 0)
     {
         if ($includenumber) {
             $chars = 'abcdefghijklmnopqrstuvwxyzABCDEFGHJKLMNPQEST123456789';
         } else {
             $chars = 'abcdefghijklmnopqrstuvwxyz';
         }
         $len = strlen($chars);
         $randStr = '';
         for ($i = 0; $i < $randLength; $i++) {
             $randStr .= $chars[mt_rand(0, $len - 1)];
         }
         $tokenvalue = $randStr;
         if ($addtime) {
             $tokenvalue = $randStr . time();
         }
         return $tokenvalue;
     }