php 文件上传带压缩图片

<?php

    class upload
    {
        var $upload_name;                   //上传文件名
        var $upload_tmp_name;               //上传临时文件名
        var $upload_final_name;             //上传文件的最终文件名
        var $upload_target_dir;             //文件被上传到的目标目录
        var $upload_target_path;            //文件被上传到的最终路径
        var $upload_filetype ;              //上传文件类型
        var $allow_uploadedfile_type;       //允许的上传文件类型
        var $upload_file_size;              //上传文件的大小
        var $allow_uploaded_maxsize=5000;   //允许上传文件的最大值
        var $image_w=900;                   //要显示图片的宽
        var $image_h=350;                   //要显示图片的高

        function __construct()
        {
            $this->upload_name = $_FILES["file"]["name"]; //取得上传文件名
            $this->upload_filetype = $_FILES["file"]["type"];
            $this->upload_final_name = date("Y-m-d H:i:s").$this->upload_name;
            $this->upload_tmp_name = $_FILES["file"]["tmp_name"];
            $this->allow_uploadedfile_type = array("image/gif","image/jpeg");
            $this->upload_file_size = $_FILES["file"]["size"];
            $this->upload_target_dir="./upload";
        }

        function upload_file()
        {
            if(in_array($this->upload_filetype,$this->allow_uploadedfile_type))
            {
                if($this->upload_file_size < $this->allow_uploaded_maxsize)
                {
                    if(!is_dir($this->upload_target_dir))
                    {
                        mkdir($this->upload_target_dir);
                    }
                    $this->upload_target_path = $this->upload_target_dir."/".$this->upload_final_name;
                    if(!move_uploaded_file($this->upload_tmp_name,$this->upload_target_path))
                    echo "<font color=red>文件上传失败！</font>";
                }
                else
                {
                    echo("<font color=red>文件太大,上传失败！</font>");
                }
            }
            else
            {
                echo("不支持此文件类型，请重新选择");
            }
        }

    }

?>
//该片段来自于http://outofmemory.cn