CI自带的文件上传及生成缩略图

   /*
    * 文件上传
    * @param  $upload_path 文件上传路径
    * @param  $formpic 表单name属性名称
    */
    private function doUpload($upload_path,$formpic){
        //配置
        //设置文件上传的路径
        $config['upload_path'] = $upload_path;
        //限制文件上传的类型
        $config['allowed_types'] = 'gif|jpg|png|jpeg';
        //限制文件上传的大小
        $config['max_size'] = '2048';
        //设置文件上传的路径
        $config['file_name'] = time() . mt_rand(1000,9999);
        //载入上传类
        $this->load->library('Upload', $config);
        //执行上传
        $status = $this->upload->do_upload($formpic);
    }
   /**
    * 生成缩略图
    * @param  $path 原图的本地路径
    * @param  $newPath 缩略图存储路径
    */
    private function dealthumb($path,$newPath,$width,$height){
        $config['image_library'] = 'gd2';
        $config['source_image'] = $path;
        $config['new_image'] = $newPath; 
        $config['create_thumb'] = TRUE;
        //生成的缩略图将在保持纵横比例 在宽度和高度上接近所设定的width和height
        $config['maintain_ratio'] = TRUE;
        $config['width'] = $width;
        $config['height'] = $height;
        //载入图像处理类库  
        $this->load->library('Image_lib');
        $this->image_lib->initialize($config);  
        $this->image_lib->resize();
        $this->image_lib->clear();
    }