Detailed explanation of methods and examples of PHP file upload class

define('ROOT_PATH',dirname(__FILE__)); //网站根目录
define('UPDIR','/uploads/'); //上传主目录

<?php
  //上传文件类
  class FileUpload {
    private $error;  //错误代码
    private $maxsize; //表单最大值
    private $type;  //类型
    private $typeArr = array(&#39;image/jpeg&#39;,&#39;image/pjpeg&#39;,&#39;image/png&#39;,&#39;image/x-png&#39;,&#39;image/gif&#39;); //类型合集
    private $path;  //目录路径
    private $today;  //今天目录
    private $name;  //文件名
    private $tmp;  //临时文件
    private $linkpath; //链接路径
    private $linktotay; //今天目录（相对）
    //构造方法，初始化
    public function __construct($_file,$_maxsize) {
       $this->error = $_FILES[$_file][&#39;error&#39;];
       $this->maxsize = $_maxsize / 1024;
       $this->type = $_FILES[$_file][&#39;type&#39;];
       $this->path = ROOT_PATH.UPDIR;
       $this->linktotay = date(&#39;Ymd&#39;).&#39;/&#39;;
       $this->today = $this->path.$this->linktotay;
       $this->name = $_FILES[$_file][&#39;name&#39;];
       $this->tmp = $_FILES[$_file][&#39;tmp_name&#39;];
       $this->checkError();
       $this->checkType();
       $this->checkPath();
       $this->moveUpload();
    }
    //返回路径
    public function getPath() {
       $_path = $_SERVER["SCRIPT_NAME"];
       $_dir = dirname(dirname($_path));
       if ($_dir == &#39;\\&#39;) $_dir = &#39;/&#39;;
       $this->linkpath = $_dir.$this->linkpath;
       return $this->linkpath;
    }
    //移动文件
    private function moveUpload() {
       if (is_uploaded_file($this->tmp)) {
         if (!move_uploaded_file($this->tmp,$this->setNewName())) {
            Tool::alertBack(&#39;警告：上传失败！&#39;);
         }
       } else {
         Tool::alertBack(&#39;警告：临时文件不存在！&#39;);
       }
    }
    //设置新文件名
    private function setNewName() {
       $_nameArr = explode(&#39;.&#39;,$this->name);
       $_postfix = $_nameArr[count($_nameArr)-1];
       $_newname = date(&#39;YmdHis&#39;).mt_rand(100,1000).&#39;.&#39;.$_postfix;
       $this->linkpath = UPDIR.$this->linktotay.$_newname;
       return $this->today.$_newname;
    }
    //验证目录
    private function checkPath() {
       if (!is_dir($this->path) || !is_writeable($this->path)) {
         if (!mkdir($this->path)) {
            Tool::alertBack(&#39;警告：主目录创建失败！&#39;);
         }
       }
       if (!is_dir($this->today) || !is_writeable($this->today)) {
         if (!mkdir($this->today)) {
            Tool::alertBack(&#39;警告：子目录创建失败！&#39;);
         }
       }
    }
    //验证类型
    private function checkType() {
       if (!in_array($this->type,$this->typeArr)) {
         Tool::alertBack(&#39;警告：不合法的上传类型！&#39;);
       }
    }
    //验证错误
    private function checkError() {
       if (!empty($this->error)) {
         switch ($this->error) {
            case 1 :
              Tool::alertBack(&#39;警告：上传值超过了约定最大值！&#39;);
              break;
            case 2 :
              Tool::alertBack(&#39;警告：上传值超过了&#39;.$this->maxsize.&#39;KB！&#39;);
              break;
            case 3 :
              Tool::alertBack(&#39;警告：只有部分文件被上传！&#39;);
              break;
            case 4 :
              Tool::alertBack(&#39;警告：没有任何文件被上传！&#39;);
              break;
            default:
              Tool::alertBack(&#39;警告：未知错误！&#39;);
         }
       }
    }
  }
?>

<?php
  class Tool {
     //弹窗返回
     static public function alertBack($_info) {
       echo "<script type=&#39;text/javascript&#39;>alert(&#39;$_info&#39;);history.back();</script>";
       exit();
     }     //弹窗赋值关闭
     static public function alertOpenerClose($_info,$_path) {
       echo "<script type=&#39;text/javascript&#39;>alert(&#39;$_info&#39;);</script>";
       echo "<script type=&#39;text/javascript&#39;>opener.document.content.thumbnail.value=&#39;$_path&#39;;</script>";
       echo "<script type=&#39;text/javascript&#39;>opener.document.content.pic.style.display=&#39;block&#39;;</script>";
       echo "<script type=&#39;text/javascript&#39;>opener.document.content.pic.src=&#39;$_path&#39;;</script>";
       echo "<script type=&#39;text/javascript&#39;>window.close();</script>";
       exit();
     } }
?>

<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN"
"http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
<html xmlns="http://www.w3.org/1999/xhtml">
  <head>
     <meta http-equiv="Content-Type" content="text/html; charset=utf-8" />
     <title>main</title>
  </head>
  <body>
     <form name="content" method="post" action="?action=add">
     <input type="text" name="thumbnail" class="text" readonly="readonly" /> <input type="button" value="上传" onclick="centerWindow(&#39;./upfile.html&#39;,&#39;upfile&#39;,&#39;400&#39;,&#39;100&#39;)" /> <img name="pic" style="display:none;" /> ( * 必须是jpg,gif,png，并且200k内) <br />
     </form>
  </body>
</html>

<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
<html xmlns="http://www.w3.org/1999/xhtml">
  <head>
    <meta http-equiv="Content-Type" content="text/html; charset=utf-8" />
    <title>上传图片</title>
  </head>
  <body></p><p>   <form method="post" action="./upload.php" enctype="multipart/form-data" style="text-align:center;margin:30px;">
    <input type="hidden" name="MAX_FILE_SIZE" value="204800" />
    <input type="file" name="pic" />
    <input type="submit" name="send" value="确定上传" />
</form></p><p></body>
</html>

<?php
  require &#39;FileUpload.class.php&#39;;
  if (isset($_POST[&#39;send&#39;])) {
    $_fileupload = new FileUpload(&#39;pic&#39;,$_POST[&#39;MAX_FILE_SIZE&#39;]);
    $_path = $_fileupload->getPath();
    Tool::alertOpenerClose(&#39;文件上传成功！&#39;,$_path);
  } else {
    Tool::alertBack(&#39;警告：文件过大或者其他未知错误导致浏览器崩溃！&#39;);
  }
?>