php通过文件头检测文件类型通用类（zip,rar…)

<?php 
 
/*通过文件名，获得文件类型*
 *@author chengmo QQ:8292669*
 *@copyright <a href="http://www.cnblogs.com/chengmo">http://www.cnblogs.com/chengmo</a> 2010-10-17
 *@version 0.1
 *$filename="d:/1.png";echo cFileTypeCheck::getFileType($filename); 打印：png
 */
class cFileTypeCheck
{
    private static $_TypeList=array();
    private static $CheckClass=null;
    private function __construct($filename)
    {
        self::$_TypeList=$this->getTypeList();
    }
 
    /**
     *处理文件类型映射关系表*
     *
     * @param string $filename 文件类型
     * @return string 文件类型，没有找到返回：other
     */
    private function _getFileType($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); //只读15字节 各个不同文件类型，头信息不一样。
        fclose($file);
         
        $typelist=self::$_TypeList;
        foreach ($typelist as $v)
        {
            $blen=strlen(pack("H*",$v[0])); //得到文件头标记字节数
            $tbin=substr($bin,0,intval($blen)); ///需要比较文件头长度
             
            if(strtolower($v[0])==strtolower(array_shift(unpack("H*",$tbin)))) 
            {
                return $v[1];
            }
        }
        return $filetype;
    }
     
    /**
     *得到文件头与文件类型映射表*
     *
     * @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);
    }
}