PHP detects file type class code through file header_PHP tutorial

/*Get the file type through the file name*
*@author chengmo*
*@copyright cnblog.com/chengmo 2010-10-19
*@version 0.1
*$filename="d:/1.png";echo cFileTypeCheck::getFileType($filename); Print: png
*/
class cFileTypeCheck
{
private static $_TypeList=array ();
private static $CheckClass=null;
private function __construct($filename)
{
self::$_TypeList=$this->getTypeList();
}
/**
*Process file type mapping table*
*
* @param string $filename file type
* @return string file type, not found return: other
*/
private function _getFileType($filename)
{
$filetype="other";
if(!file_exists($filename)) throw new Exception( "no found file!");
$file = @fopen($filename,"rb");
if(!$file) throw new Exception("file refuse!");
$bin = fread($file, 15); //Read only 15 bytes. Different file types have different header information.
fclose($file);
$typelist=self::$_TypeList;
foreach ($typelist as $v)
{
$blen=strlen(pack("H*" ,$v[0])); //Get the number of bytes marked in the file header
$tbin=substr($bin,0,intval($blen)); ///Need to compare the file header length
if (strtolower($v[0])==strtolower(array_shift(unpack("H*",$tbin))))
{
return $v[1];
}
}
return $filetype;
}
/**
*Get file header and file type mapping table*
*
* @return array array(array(key,value)...)
*/
public function getTypeList()
{
return array(array("FFD8FFE1","jpg") ,
array("89504E47","png"),
array("47494638","gif"),
array("49492A00","tif"),
array("424D ","bmp"),
array("41433130","dwg"),
array("38425053","psd"),
array("7B5C727466","rtf"),
array("3C3F786D6C","xml"),
array("68746D6C3E","html"),
array("44656C69766572792D646174","eml"),
array("CFAD12FEC5FD746F", "dbx"),
array("2142444E","pst"),
array("D0CF11E0","xls/doc"),
array("5374616E64617264204A","mdb"),
array("FF575043","wpd"),
array("252150532D41646F6265","eps/ps"),
array("255044462D312E","pdf"),
array("E3828596 ","pwl"),
array("504B0304","zip"),
array("52617221","rar"),
array("57415645","wav"),
array("41564920","avi"),
array("2E7261FD","ram"),
array("2E524D46","rm"),
array("000001BA", "mpg"),
array("000001B3","mpg"),
array("6D6F6F76","mov"),
array("3026B2758E66CF11","asf"),
array("4D546864","mid"));
}
public static function getFileType($filename)
{
if(!self::$CheckClass) self::$CheckClass=new self($filename);
$class=self::$CheckClass;
return $class->_getFileType($filename);
}
}
?>