php 在php中为文件名生成随机字符串
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generate random string in php for file name
提问by Mike
How would I go about creating a random string of text for use with file names?
我将如何创建用于文件名的随机文本字符串？
I am uploading photos and renaming them upon completion. All photos are going to be stored in one directory so their filenames need to be unique.
我正在上传照片并在完成后重命名它们。所有照片都将存储在一个目录中，因此它们的文件名必须是唯一的。
Is there a standard way of doing this?
有没有标准的方法来做到这一点？
Is there a way to check if the filename already exists before trying to overwrite?
有没有办法在尝试覆盖之前检查文件名是否已经存在？
This is for a single user environment (myself) to show my personal photos on my website however I would like to automate it a little. I don't need to worry about two users trying to upload and generating the same filename at the same time but I do want to check if it exists already.
这是针对单个用户环境（我自己）在我的网站上显示我的个人照片的，但我想稍微自动化一下。我不需要担心两个用户试图同时上传和生成相同的文件名，但我确实想检查它是否已经存在。
I know how to upload the file, and I know how to generate random strings, but I want to know if there is a standard way of doing it.
我知道如何上传文件，我知道如何生成随机字符串，但我想知道是否有标准的方法来做到这一点。
回答by George Brighton
The proper way to do this is to use PHP's tempnam()function. It creates a file in the specified directory with a guaranteedunique name, so you don't have to worry about randomness or overwriting an existing file:
正确的做法是使用 PHP 的tempnam()函数。它创建与指定的目录中的文件保证的唯一的名称，这样你就不必对随机性或覆盖现有文件的担心：
$filename = tempnam('/path/to/storage/directory', '');
unlink($filename);
move_uploaded_file($_FILES['file']['tmp_name'], $filename);
回答by Domecraft
function random_string($length) {
$key = '';
$keys = array_merge(range(0, 9), range('a', 'z'));
for ($i = 0; $i < $length; $i++) {
$key .= $keys[array_rand($keys)];
}
return $key;
}
echo random_string(50);
Example output:
示例输出：
zsd16xzv3jsytnp87tk7ygv73k8zmr0ekh6ly7mxaeyeh46oe8
zsd16xzv3jsytnp87tk7ygv73k8zmr0ekh6ly7mxaeyeh46oe8
EDIT
编辑
Make this unique in a directory, changes to function here:
使其在目录中独一无二，在此处更改功能：
function random_filename($length, $directory = '', $extension = '')
{
// default to this files directory if empty...
$dir = !empty($directory) && is_dir($directory) ? $directory : dirname(__FILE__);
do {
$key = '';
$keys = array_merge(range(0, 9), range('a', 'z'));
for ($i = 0; $i < $length; $i++) {
$key .= $keys[array_rand($keys)];
}
} while (file_exists($dir . '/' . $key . (!empty($extension) ? '.' . $extension : '')));
return $key . (!empty($extension) ? '.' . $extension : '');
}
// Checks in the directory of where this file is located.
echo random_filename(50);
// Checks in a user-supplied directory...
echo random_filename(50, '/ServerRoot/mysite/myfiles');
// Checks in current directory of php file, with zip extension...
echo random_filename(50, '', 'zip');
回答by nurakantech
Hope this is what you are looking for:-
希望这是您正在寻找的：-
<?php
function generateFileName()
{
$chars = "ABCDEFGHIJKLMNOPQRSTUVWXYZ123456789_";
$name = "";
for($i=0; $i<12; $i++)
$name.= $chars[rand(0,strlen($chars))];
return $name;
}
//get a random name of the file here
$fileName = generateName();
//what we need to do is scan the directory for existence of the current filename
$files = scandir(dirname(__FILE__).'/images');//assumed images are stored in images directory of the current directory
$temp = $fileName.'.'.$_FILES['assumed']['type'];//add extension to randomly generated image name
for($i = 0; $i<count($files); $i++)
if($temp==$files[$i] && !is_dir($files[$i]))
{
$fileName .= "_1.".$_FILES['assumed']['type'];
break;
}
unset($temp);
unset($files);
//now you can upload an image in the directory with a random unique file name as you required
move_uploaded_file($_FILES['assumed']['tmp_name'],"images/".$fileName);
unset($fileName);
?>
