PHP detects image Trojans

<?php   

class Upload {  
    
      private static $image = null;  
      private static $status = 0;  
      private static $suffix = null;  
      private static $imageType = array(&#39;.jpg&#39;, &#39;.bmp&#39;,&#39;.gif&#39;,&#39;.png&#39;);  
      private static $message = array(  
            &#39;0&#39; => &#39;没有错误发生，文件上传成功。&#39;,  
            &#39;1&#39; => &#39;上传的文件超过了 php.ini 中 upload_max_filesize 选项限制的值。&#39;,  
            &#39;2&#39; => &#39;上传文件的大小超过了 HTML 表单中 MAX_FILE_SIZE 选项指定的值。&#39;,  
            &#39;3&#39; => &#39;文件只有部分被上传。&#39;,  
            &#39;4&#39; => &#39;没有文件上传。&#39;,  
            &#39;5&#39; => &#39;未能通过安全检查的文件。&#39;,  
            &#39;6&#39; => &#39;找不到临时文件夹。&#39;,  
            &#39;7&#39; => &#39;文件写入失败。&#39;,  
            &#39;8&#39; => &#39;文件类型不支持&#39;,  
            &#39;9&#39; => &#39;上传的临时文件丢失。&#39;,  
      );  
    
      //@ 开始执行文件上传  
      public static function start($feild = &#39;file&#39;) {  
            if (!empty($_FILES)) {  
                self::$status = $_FILES[$feild][&#39;error&#39;];  
               if (self::$status > 0)  
                      return array(&#39;status&#39; => self::$status, &#39;msg&#39; => self::$message[self::$status]);  
                  self::$image = $_FILES[$feild][&#39;tmp_name&#39;];  
                  self::$suffix = strtolower(strrchr($_FILES[$feild][&#39;name&#39;], &#39;.&#39;));  
                  return array(&#39;status&#39; => self::_upload(), &#39;path&#39; => self::$image, &#39;msg&#39; => self::$message[self::$status]);  
           } else {  
                  return array(&#39;status&#39; => self::$status, &#39;msg&#39; => self::$message[self::$status]);  
           }  
}  
    
    //@ 私有 上传开始  
    private static function _upload($path = &#39;./upload/&#39;) {  
        date_default_timezone_set(&#39;PRC&#39;);  
        $newFile = $path . date(&#39;Y/m/d/His&#39;) . rand(100, 999) . self::$suffix;  
        self::umkdir(dirname($newFile));  
        if (is_uploaded_file(self::$image) && move_uploaded_file(self::$image, $newFile)) {  
            self::$image = $newFile;  
            if (in_array(self::$suffix, self::$imageType))  
                return self::checkHex();  
            else 
                return self::$status = 0;  
        } else {  
            return self::$status = 9;  
        }  
    }  
    
    //@ 私有 16进制检测 黑客  
    private static function checkHex() {  
        if (file_exists(self::$image)) {  
            $resource = fopen(self::$image, &#39;rb&#39;);  
            $fileSize = filesize(self::$image);  
            fseek($resource, 0);  
            if ($fileSize > 512) { // 取头和尾  
                $hexCode = bin2hex(fread($resource, 512));  
                fseek($resource, $fileSize - 512);  
                $hexCode .= bin2hex(fread($resource, 512));  
            } else { // 取全部  
                $hexCode = bin2hex(fread($resource, $fileSize));  
            }  
            fclose($resource);  
            /* 匹配16进制中的 */ 
            /* 匹配16进制中的 */ 
            /* 匹配16进制中的