面向对象的文件上传类实现与功能解析

<?php
header("Content-Type:text/html; charset=utf-8");
if($_POST['submit']){
$upfiles = new Upload();
$upfiles->upload_file();
}
class Upload{
        /*作者：mckee 来自：www.phpddt.com*/
public $upload_name; //上传文件名
public $upload_tmp_name; //上传临时文件名
public $upload_final_name; //上传文件的最终文件名
public $upload_target_dir; //文件被上传到的目标目录
public $upload_target_path;     //文件被上传到的最终路径
public $upload_filetype ; //上传文件类型
public $allow_uploadedfile_type; //允许的上传文件类型
public $upload_file_size; //上传文件的大小
public $allow_uploaded_maxsize=10000000;  //允许上传文件的最大值
//构造函数
public function __construct()
{
$this->upload_name = $_FILES["file"]["name"]; //取得上传文件名
$this->upload_filetype = $_FILES["file"]["type"];
$this->upload_tmp_name = $_FILES["file"]["tmp_name"];
$this->allow_uploadedfile_type = array('jpeg','jpg','png','gif','bmp','doc','zip','rar','txt','wps');
$this->upload_file_size = $_FILES["file"]["size"];
$this->upload_target_dir="./upload";
}
//文件上传
public function upload_file()
{