Detailed explanation of php file upload class examples

/**
$file=new class_file($file_array,"flash/");
 $file->set_allow_type(array("jpg","jpeg","gif"));
 $file->is_limit_size();
 if(!$file->allow_file_size()){
   echo $file->error;
   exit;
 }
 if(!$file->allow_file_type()){
    echo $file->error;
    exit();
  }else if(!$file->uploadfile()){
  echo $file->error;
  exit;
 }
**/
<?php
 class class_file{
   private $file_type;
   private $file_size;
   private $save_path;
   private $file_path;
   private $allow_type=array();
   private $allow_size;
   private $file_name;
   private $flag=false;
   private $mime_type;
   private $is_limit_size=false;
   public $error;
   //构造函数
  function class_file($file_array,$save_path){
       $this->file_path=$file_array[&#39;tmp_name&#39;];
       $this->file_size=$file_array[&#39;size&#39;];
       $this->file_type=$file_array[&#39;type&#39;];
       $this->save_path=$save_path;
    }
    //设置允许的文件类型
   function set_allow_type($allow_type){
      $this->allow_type=$allow_type;
    }
    //设置允许的文件大小
   function set_allow_size($allow_size){
      $this->allow_size=$allow_size;
    }
    //文件上传
   public function uploadfile(){
     if(!$this->allow_file_type()){
     $this->file_name();
     }
     if(move_uploaded_file($this->file_path,$this->save_path.$this->file_name)){
       return true;
     }else{
       $this->error="文件上传失败";
       return;
     }
   }
//判断文件上传的类型
   function allow_file_type(){
     $this->file_name();
     if(in_array($this->mime_type,$this->allow_type)){
         return true;
       }else{
         $this->error="不允许上传的类型";
         exit();
       }
   }
 //判断文件上传的大小
   function allow_file_size($size=100){
     if($this->is_limit_size){
     $this->set_allow_size($size);
     if($this->allow_size>=$this->file_size){
       return true;
     }else{
       $this->error="超过文件上传大小限制";
     }
     }
   }
 //是否限制文件大小
   function is_limit_size(){
     $this->is_limit_size=true;
   }
//文件类型和文件名称
   function file_name(){
    $this->mime_type=substr($this->file_type,strpos($this->file_type,"/")+1);
   if($this->mime_type=="pjpeg"){
     $this->mime_type="jpg";
    }
   if($this->mime_type=="x-ms-wma"){
      $this->mime_type="wma";
    }
    if($this->mime_type=="x-ms-wmv"){
      $this->mime_type="wmv";
    }
    $this->file_name=date("YmdHis").".$this->mime_type";
   }
   function _get_file_name(){
     return $this->file_name;
   }
 }
?>