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。