利用Codeigniter怎么实现一个文件批量上传功能

/**
 * 多文件上传
 * 
 * @author Dream <dream@shanjing-inc.com>
 */
public function multiple_uploads() {
  //载入所需类库
  $this->load->library('upload');
  
  //配置上传参数
  $upload_config = array(
      'upload_path'  => '',
      'allowed_types' => 'jpg|png|gif',
      'max_size'   => '500',
      'max_width'   => '1024',
      'max_height'  => '768',
  );
  $this->upload->initialize($upload_config);
    
  //循环处理上传文件
  foreach ($_FILES as $key => $value) {
    if (!empty($key['name'])) {
      if ($this->upload->do_upload($key)) {
        //上传成功
        print_r($this->upload->data());
      } else {
        //上传失败
        echo $this->upload->display_errors();
      }
    }
  }
}

function upload() {
    $config['upload_path'] = './uploads/'; 
    /*这里的uploads是相对于index.php的,也就是入口文件,这个千万不要弄错哦!
    否则就会报错"The upload path does not appear to be valid."; 
    */
    $config['allowed_types'] = 'gif|jpg|png';
    /*我试着去上传其它类型的文件,这里一定要注意顺序! 
    A problem was encountered while attempting to move the uploaded file to the final destination.
    这个错误一般是上传文件的文件名不能是中文名,这个很郁闷!还未解决,大家可以用其它方法,重新改一下文件名就可以解决了! 
    $config['allowed_types'] = 'zip|gz|png|gif|jpg';(正确)
    $config['allowed_types'] = 'png|gif|jpg|zip|gz';(错误)
    */
    $config['max_size'] = '1024';
    $config['max_width'] = '1024';
    $config['max_height'] = '768';

    $config['file_name'] = time(); //文件名不使用原始名
    $this->load->library('upload', $config);
    if(!$this->upload->do_upload()) {
        echo $this->upload->display_errors();
    }else{

       $data['upload_data']=$this->upload->data(); //文件的一些信息
       $img=$data['upload_data']['file_name']; //取得文件名

       echo $img."<br>";

       foreach($data['upload_data'] as $item => $value){
       echo $item.":".$value."<br>";

      }

    }
}