具有上面讨论的一些函数的类。

$options['numeric'] = true;
$options['uppercase'] = true;
$options['lowercase'] = true;
$new = new RandomString($options);

class RandomString
{
    /**
     * @var array
     */
    private $default = ['numeric' => true, 'uppercase' => true, 'lowercase' => true];

    /**
     * @var array
     */
    private $options;

    /**
     * array
     */
    private $whitelist = ['numeric', 'uppercase', 'lowercase'];

    /**
     * RandomString constructor.
     *
     * @param array $options
     */
    public function __construct(array $options = [])
    {
        $this->options = $this->default;
        if(!empty($options))
        {
            $options = array_intersect_key($options, array_flip($this->whitelist));
            if(empty($options))
            {
                $this->options = $this->default;
            }else
            {
                $this->options = $options;
            }
        }
    }

    /**
     * @return string
     */
    private function returnCharacters(){

        $options = $this->options;

        $numbers = '0123456789';
        $uppercase = 'ABCDEFGHIJKLMNOPQRSTUVWXYZ';
        $lowercase = "abcdefghijklmnopqrstuvwxyz";

        $characters = '';
        if(isset($options['numeric']) && $options['numeric'] === true){
            $characters .= $numbers;
        }

        if(isset($options['uppercase']) && $options['uppercase'] === true){
            $characters .= $uppercase;
        }

        if(isset($options['lowercase']) && $options['lowercase'] === true){
            $characters .= $lowercase;
        }
        return $characters;
    }

    /**
     * @param $length
     * @param $quantity
     * @return string
     */
    public function randomString($length, $quantity) {

        $string = '';
        $characters = $this->returnCharacters();

        for ($j = 0; $j < $quantity; $j++) {
            for($i = 0; $i < $length; $i++){
                $string .= $characters[mt_rand(0, strlen($characters) - 1)];
            }
            $string .= "\n";
        }
        return $string;
    }

    /**
     * @return array
     */
    public function getOptions()
    {
        return $this->options;
    }

    /**
     * @return mixed
     */
    public function getWhitelist()
    {
        return $this->whitelist;
    }

这一个是从管理员来源:

/** Get a random string
* @return string 32 hexadecimal characters
*/
function rand_string() {
    return md5(uniqid(mt_rand(), true));
}

管理员，用PHP编写的数据库管理工具。

短的方法。

这里有一些生成随机字符串的最短方法

<?php
echo $my_rand_strng = substr(str_shuffle("0123456789abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ"), -15); 

echo substr(md5(rand()), 0, 7);

echo str_shuffle(MD5(microtime()));
?>

请尝试这个函数来生成一个自定义的随机字母数字字符串:

<?php
  function random_alphanumeric($length) {
    $chars = 'abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ12345689';
    $my_string = '';
    for ($i = 0; $i < $length; $i++) {
      $pos = random_int(0, strlen($chars) -1);
      $my_string .= substr($chars, $pos, 1);
    }
    return $my_string;
  }
?>

你可以通过将字符串的长度传递给函数来调整结果，如下所示:

  $test_with_50_items = random_alphanumeric(50); // 50 characters
  echo $test_with_50_items;

示例(test_with_50_items): Y1FypdjVbFCFK6Gh9FDJpe6dciwJEfV6MQGpJqAfuijaYSZ86

如果你需要超过50个字符或更少，只需按你喜欢的方式调用函数:

  $test_with_27_items = random_alphanumeric(27); // 27 characters
  echo $test_with_27_items;

如果你需要两个或更多唯一的字符串，你可以使用while循环，这样你肯定会得到两个唯一的字符串…你可以用更多的弦做同样的事情，唯一的限制是你的幻想……

  $string_1 = random_alphanumeric(50);
  $string_2 = random_alphanumeric(50);
  while ($string_1 == $string_2) {
    $string_1 = random_alphanumeric(50);
    $string_2 = random_alphanumeric(50);
    if ($string_1 != $string_2) {
       break;
    }
  }
  echo $string_1;
  echo "<br>\n";
  echo $string_2;

$string_1： KkvUwia8rbDEV2aChWqm3AgeUZqyrRbUx2AxVhx5s4TSJ2VwA4

$string_2： XraO85YfxBBCInafvwipSOJwLmk6JMWiuWOxYQDnXohcn2D8K6

根据PHP 8.3, random_int()是“默认安全的”

以前的答案会生成不安全或难以输入的密码。

这是安全的，并且提供了用户更有可能实际使用的密码，而不是因为一些薄弱的东西而被丢弃。

// NOTE: On PHP 5.x you will need to install https://github.com/paragonie/random_compat

/**
 * Generate a password that can easily be typed by users.
 *
 * By default, this will sacrifice strength by skipping characters that can cause
 * confusion. Set $allowAmbiguous to allow these characters.
 */
static public function generatePassword($length=12, $mixedCase=true, $numericCount=2, $symbolCount=1, $allowAmbiguous=false, $allowRepeatingCharacters=false)
{
  // sanity check to prevent endless loop
  if ($numericCount + $symbolCount > $length) {
    throw new \Exception('generatePassword(): $numericCount + $symbolCount are too high');
  }

  // generate a basic password with just alphabetic characters
  $chars  = 'qwertyupasdfghjkzxcvbnm';
  if ($mixedCase) {
    $chars .= 'QWERTYUPASDFGHJKZXCVBNML';
  }
  if ($allowAmbiguous) {
    $chars .= 'iol';
    if ($mixedCase) {
      $chars .= 'IO';
    }
  }

  $password = '';
  foreach (range(1, $length) as $index) {
    $char = $chars[random_int(0, strlen($chars) - 1)];

    if (!$allowRepeatingCharacters) {
      while ($char == substr($password, -1)) {
        $char = $chars[random_int(0, strlen($chars) - 1)];
      }
    }

    $password .= $char;
  }


  // add numeric characters
  $takenSubstitutionIndexes = [];

  if ($numericCount > 0) {
    $chars = '23456789';
    if ($allowAmbiguous) {
      $chars .= '10';
    }

    foreach (range(1, $numericCount) as $_) {
      $index = random_int(0, strlen($password) - 1);
      while (in_array($index, $takenSubstitutionIndexes)) {
        $index = random_int(0, strlen($password) - 1);
      }

      $char = $chars[random_int(0, strlen($chars) - 1)];
      if (!$allowRepeatingCharacters) {
        while (substr($password, $index - 1, 1) == $char || substr($password, $index + 1, 1) == $char) {
          $char = $chars[random_int(0, strlen($chars) - 1)];
        }
      }

      $password[$index] = $char;
      $takenSubstitutionIndexes[] = $index;
    }
  }

  // add symbols
  $chars = '!@#$%&*=+?';
  if ($allowAmbiguous) {
    $chars .= '^~-_()[{]};:|\\/,.\'"`<>';
  }

  if ($symbolCount > 0) {
    foreach (range(1, $symbolCount) as $_) {
      $index = random_int(0, strlen($password) - 1);
      while (in_array($index, $takenSubstitutionIndexes)) {
        $index = random_int(0, strlen($password) - 1);
      }

      $char = $chars[random_int(0, strlen($chars) - 1)];
      if (!$allowRepeatingCharacters) {
        while (substr($password, $index - 1, 1) == $char || substr($password, $index + 1, 1) == $char) {
          $char = $chars[random_int(0, strlen($chars) - 1)];
        }
      }

      $password[$index] = $char;
      $takenSubstitutionIndexes[] = $index;
    }
  }

  return $password;
}

我已经测试了那里最流行的函数的性能，在我的盒子上生成1 000 000个32个符号的字符串所需的时间是:

2.5 $s = substr(str_shuffle(str_repeat($x='0123456789abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ', ceil($length/strlen($x)) )),1,32);
1.9 $s = base64_encode(openssl_random_pseudo_bytes(24));
1.68 $s = bin2hex(openssl_random_pseudo_bytes(16));
0.63 $s = base64_encode(random_bytes(24));
0.62 $s = bin2hex(random_bytes(16));
0.37 $s = substr(md5(rand()), 0, 32);
0.37 $s = substr(md5(mt_rand()), 0, 32);

请注意，它到底有多长并不重要，重要的是哪个更慢，哪个更快，因此您可以根据您的要求进行选择，包括密码准备等。

如果需要小于32个字符的字符串，则在MD5周围添加substr()以保证准确性。

为了回答:字符串没有被连接，而是被覆盖，函数的结果没有被存储。