php从文件夹随机读取文件的方法

 function RandomFile($folder='', $extensions='.*'){ // fix path: $folder = trim($folder); $folder = ($folder == '') ? './' : $folder; // check folder: if (!is_dir($folder)){ die('invalid folder given!'); } // create files array $files = array(); // open directory if ($dir = @opendir($folder)){ // go trough all files: while($file = readdir($dir)){ if (!preg_match('/^\.+$/', $file) and preg_match('/\.('.$extensions.')$/', $file)){ // feed the array: $files[] = $file; } } // close directory closedir($dir); } else { die('Could not open the folder "'.$folder.'"'); } if (count($files) == 0){ die('No files where found :-('); } // seed random function: mt_srand((double)microtime()*1000000); // get an random index: $rand = mt_rand(0, count($files)-1); // check again: if (!isset($files[$rand])){ die('Array index was not found! very strange!'); } // return the random file: return $folder . $files[$rand]; } //用法演示： // "jpg|png|gif" matches all files with these extensions print RandomFile('test_images/','jpg|png|gif'); // returns test_07.gif // ".*" matches all extensions (all files) print RandomFile('test_files/','.*'); // returns foobar_1.zip // "[0-9]+" matches all extensions that just // contain numbers (like backup.1, backup.2) print RandomFile('test_files/','[0-9]+'); // returns backup.7