我认为这是最好的方法。

str_shuffle(md5(rand(0,100000)))

使用下面的代码生成11个字符的随机数或根据您的要求更改数字。

$randomNum=substr(str_shuffle("0123456789abcdefghijklmnopqrstvwxyz"), 0, 11);

或者我们可以使用自定义函数来生成随机数

 function randomNumber($length){
     $numbers = range(0,9);
     shuffle($numbers);
     for($i = 0;$i < $length;$i++)
        $digits .= $numbers[$i];
     return $digits;
 }

 //generate random number
 $randomNum=randomNumber(11);

以下是我使用的方法:

md5(time() . rand());    
// Creates something like 0c947c3b1047334f5bb8a3b7adc1d97b

生成一个随机数使用 你最喜欢的随机数 发电机 乘除 得到一个与数字匹配的数字 你的代码字母表中的字符 将该索引处的项插入 你的代码字母。 重复1)，直到你有你想要的长度 想要

例如(伪代码)

int myInt = random(0, numcharacters)
char[] codealphabet = 'ABCDEF12345'
char random = codealphabet[i]
repeat until long enough

一个简单的解决方案是通过丢弃非字母数字字符将64进制转换为字母数字。

它使用random_bytes()来获得加密安全的结果。

function random_alphanumeric(int $length): string
{
    $result='';
    do
    {
        //Base 64 produces 4 characters for each 3 bytes, so most times this will give enough bytes in a single pass
        $bytes=random_bytes(($length+3-strlen($result))*2);
        //Discard non-alhpanumeric characters
        $result.=str_replace(['/','+','='],['','',''],base64_encode($bytes));
        //Keep adding characters until the string is long enough
        //Add a few extra because the last 2 or 3 characters of a base 64 string tend to be less diverse
    }while(strlen($result)<$length+3);
    return substr($result,0,$length);
}

编辑:我只是重新审视了一下，因为我需要一些更灵活的东西。这里有一个解决方案，执行得比上面的好一点，并提供了指定ASCII字符集的任何子集的选项:

<?php
class RandomText
{
    protected
        $allowedChars,
        //Maximum index to use
        $allowedCount,
        //Index values will be taken from a pool of this size
        //It is a power of 2 to keep the distribution of values even
        $distributionSize,
        //This many characters will be generated for each output character
        $ratio;
    /**
     * @param string $allowedChars characters to choose from
     */
    public function __construct(string $allowedChars)
    {
        $this->allowedCount = strlen($allowedChars);
        if($this->allowedCount < 1 || $this->allowedCount > 256) throw new \Exception('At least 1 and no more than 256 allowed character(s) must be specified.');
        $this->allowedChars = $allowedChars;
        //Find the power of 2 equal or greater than the number of allowed characters
        $this->distributionSize = pow(2,ceil(log($this->allowedCount, 2)));
        //Generating random bytes is the expensive part of this algorithm
        //In most cases some will be wasted so it is helpful to produce some extras, but not too many
        //On average, this is how many characters needed to produce 1 character in the allowed set
        //50% of the time, more characters will be needed. My tests have shown this to perform well.
        $this->ratio = $this->distributionSize / $this->allowedCount;
    }

    /**
     * @param int $length string length of required result
     * @return string random text
     */
    public function get(int $length) : string
    {
        if($length < 1) throw new \Exception('$length must be >= 1.');
        $result = '';
        //Keep track of result length to prevent having to compute strlen()
        $l = 0;
        $indices = null;
        $i = null;
        do
        {
            //Bytes will be used to index the character set. Convert to integers.
            $indices = unpack('C*', random_bytes(ceil(($length - $l) * $this->ratio)));
            foreach($indices as $i)
            {
                //Reduce to the smallest range that gives an even distribution
                $i %= $this->distributionSize;
                //If the index is within the range of characters, add one char to the string
                if($i < $this->allowedCount)
                {
                    $l++;
                    $result .= $this->allowedChars[$i];
                }
                if($l >= $length) break;
            }
        }while($l < $length);
        return $result;
    }
}

function codeGenerate() {
  $randCode  = (string)mt_rand(1000,9999);
  $randChar  = rand(65,90);
  $randInx   = rand(0,3);
  $randCode[$randInx] = chr($randChar);
  return $randCode;
}
echo codeGenerate();

输出

38I7
33V7
E836
736U