PHP development PHP complete code for image upload

Instantiate the class to realize the function

<?php
header("content-type:text/html;charset=utf-8");
class upload
{
    var $upload_name;
    var $upload_tmp_address;
    var $upload_server_name;
    var $upload_filetype ;
    var $file_type;
    var $file_server_address;
    var $image_w=600; //要显示图片的宽
    var $image_h=350; //要显示图片的高
    var $upload_file_size;
    var $upload_must_size= 500000; //允许上传文件的大小，自己设置
    function upload_file()
    {
        $this->upload_name =$_FILES["file"]["name"]; //取得上传文件名
        $this->upload_filetype = $_FILES["file"]["type"];
        $this->upload_server_name = date('y_m_dh_i_s').$this->upload_name;
        $this->upload_tmp_address = $_FILES["file"]["tmp_name"]; //取得临时地址
        $this->file_type = array(
            'image/jpg',
            'image/jpeg',
            'image/png',
            'image/gif',); //允许上传文件的类型
        $this->upload_file_size = $_FILES["file"]["size"]; //上传文件的大小
        if(in_array($this->upload_filetype,$this->file_type))
        { if($this->upload_file_size < $this->upload_must_size)
        {
            echo("上传成功，谢谢支持");
            $this->file_server_address = "../images/".$this->upload_server_name;
            move_uploaded_file($this->upload_tmp_address,$this->file_server_address);//从temp目录移出
            echo("<img src=$this->file_server_address width=$this->image_w height=$this->image_h/>"); //显示图片
        }
        else
        {
            echo("文件容量太大");
        }
        }
        else
        {
            echo("不支持此文件类型，请重新选择");
        }
    }
}
$dd = new upload;
$dd->upload_file();
?>