php从文件夹随机读取文件的方法

本文实例讲述了php从文件夹随机读取文件的方法。分享给大家供大家参考。具体实现方法如下：

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

希望本文所述对大家的php程序设计有所帮助。