问题
I have tried:
function random_pic($dir = '../myfolder') {
$files = opendir($dir . '/*.*');
$file = array_rand($files);
return $files[$file];
}
This function works using glob() but not opendir.
This returns a failed to open directory error. I guess opendir cannot accept things like *.*? Is it possible to select all files in a folder and randomly choose one?
回答1:
The opendir() function wont return a list of files/folders. It will only open a handle that can be used by closedir(), readdir() or rewinddir(). The correct usage here would be glob(), but as I see that you don't want that, you could also use scandir() like the following:
<?php
$path = "./";
$files = scandir($path);
shuffle($files);
for($i = 0; ($i < count($files)) && (!is_file($files[$i])); $i++);
echo $files[$i];
?>
I'd happily do the timing to see if this takes longer or if glob() takes longer after you admit that I'm not "wrong."
回答2:
The following 2 methods make use of
opendirto quickly read through a directory and return a random file or directory.
- All Benchmarks done use CI3 and are average of 100 pulses.
Using WAMP on Win10 Intel i54460 w/ 16GB RAM
Get Random File:
function getRandomFile($path, $type=NULL, $contents=TRUE) {
if (strpos($path, $_SERVER['DOCUMENT_ROOT']) === FALSE) $path = $_SERVER['DOCUMENT_ROOT'] . '/' . $path;
if (is_dir($path)) {
if ($dh = opendir($path)) {
$arr = [];
while (false !== ($file = readdir($dh))) {
// not a directory
if (!is_dir("$path/$file") && !preg_match('/^\.{1,2}$/', $file)) {
// fits file type
if(is_null($type)) $arr[] = $file;
elseif (is_string($type) && preg_match("/\.($type)$/", $file)) $arr[] = $file;
elseif (is_array($type)) {
$type = implode('|', $type);
if (preg_match("/\.($type)$/", $file)) $arr[] = $file;
}
}
}
closedir($dh);
if (!empty($arr)) {
shuffle($arr);
$file = $arr[mt_rand(0, count($arr)-1)];
return empty($contents) ? $file : ($contents == 'path' ? "$path/$file" : file_get_contents($file));
}
}
}
return NULL;
}
Use as simple as:
// Benchmark 0.0018 seconds *
$this->getRandomFile('directoryName');
// would pull random contents of file from given directory
// Benchmark 0.0017 seconds *
$this->getRandomFile('directoryName', 'php');
// |OR|
$this->getRandomFile('directoryName', ['php', 'htm']);
// one gets a random php file
// OR gets random php OR htm file contents
// Benchmark 0.0018 seconds *
$this->getRandomFile('directoryName', NULL, FALSE);
// returns random file name
// Benchmark 0.0019 seconds *
$this->getRandomFile('directoryName', NULL, 'path');
// returns random full file path
Get Random Directory:
function getRandomDir($path, $full=TRUE, $indexOf=NULL) {
if (strpos($path, $_SERVER['DOCUMENT_ROOT']) === FALSE) $path = $_SERVER['DOCUMENT_ROOT'] . '/' . $path;
if (is_dir($path)) {
if ($dh = opendir($path)) {
$arr = [];
while (false !== ($dir = readdir($dh))) {
if (is_dir("$path/$dir") && !preg_match('/^\.{1,2}$/', $dir)) {
if(is_null($indexOf)) $arr[] = $file;
if (is_string($indexOf) && strpos($dir, $indexOf) !== FALSE) $arr[] = $dir;
elseif (is_array($indexOf)) {
$indexOf = implode('|', $indexOf);
if (preg_match("/$indexOf/", $dir)) $arr[] = $dir;
}
}
}
closedir($dh);
if (!empty($arr)) {
shuffle($arr);
$dir = $arr[mt_rand(0, count($arr)-1)];
return $full ? "$path/$dir" : $dir;
}
}
}
return NULL;
}
Use as simple as:
// Benchmark 0.0013 seconds *
$this->getRandomDir('parentDirectoryName');
// returns random full directory path of dirs found in given directory
// Benchmark 0.0015 seconds *
$this->getRandomDir('parentDirectoryName', FALSE);
// returns random directory name
// Benchmark 0.0015 seconds *
$this->getRandomDir('parentDirectoryName', FALSE, 'dirNameContains');
// returns random directory name
Use in Combo Like:
$dir = $this->getRandomDir('dirName');
$file = $this->getRandomFile($dir, 'mp3', FALSE);
// returns a random mp3 file name.
// Could be used to load random song via ajax.
single line
/** getRandomFile(String)
* Simple method for retrieving a random file from a directory
**/
function getRandomFile($path, $type=NULL, $contents=TRUE) { if (strpos($path, $_SERVER['DOCUMENT_ROOT']) === FALSE) $path = $_SERVER['DOCUMENT_ROOT'] . '/' . $path; if (is_dir($path)) { if ($dh = opendir($path)) { $arr = []; while (false !== ($file = readdir($dh))) { if (!is_dir("$path/$file") && !preg_match('/^\.{1,2}$/', $file)) { if(is_null($type)) $arr[] = $file; elseif (is_string($type) && preg_match("/\.($type)$/", $file)) $arr[] = $file; elseif (is_array($type)) { $type = implode('|', $type); if (preg_match("/\.($type)$/", $file)) $arr[] = $file; } } } closedir($dh); if (!empty($arr)) { shuffle($arr); $file = $arr[mt_rand(0, count($arr)-1)]; return empty($contents) ? $file : ($contents == 'path' ? "$path/$file" : file_get_contents($file)); } } } return NULL; }
/** getRandomDir(String)
* Simple method for retrieving a random directory
**/
function getRandomDir($path, $full=TRUE, $indexOf=NULL) { if (strpos($path, $_SERVER['DOCUMENT_ROOT']) === FALSE) $path = $_SERVER['DOCUMENT_ROOT'] . '/' . $path; if (is_dir($path)) { if ($dh = opendir($path)) { $arr = []; while (false !== ($dir = readdir($dh))) { if (is_dir("$path/$dir") && !preg_match('/^\.{1,2}$/', $dir)) { if(is_null($indexOf)) $arr[] = $file; if (is_string($indexOf) && strpos($dir, $indexOf) !== FALSE) $arr[] = $dir; elseif (is_array($indexOf)) { $indexOf = implode('|', $indexOf); if (preg_match("/$indexOf/", $dir)) $arr[] = $dir; } } } closedir($dh); if (!empty($arr)) { shuffle($arr); $dir = $arr[mt_rand(0, count($arr)-1)]; return $full ? "$path/$dir" : $dir; } } } return NULL; }
/* This is only here to make copying easier. */
Just a Note about
glob&&scandir.
I made alternate versions of thegetRandomDirusing each.
Usingscandirhad very little if any difference in benchmarks (from -.001 to +.003)
Usingglobwas quite noticeably slower! Anywhere from +.5 to +1.100 difference on each call.
来源：https://stackoverflow.com/questions/12119304/select-random-file-using-opendir