php检测文件类型（根据文件header信息)_PHP教程

文章提供一款php教程检测文件类型（根据文件header信息)哦，他可以根据用户发布的文件头部信息来确实文件的类型。

/*通过文件名，获得文件类型*
*@author chengmo*
*@copyright cnblog.com/chengmo 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 $filetype;
}
/**
*得到文件头与文件类型映射表*
*
* @return array array(array('key',value)...)
*/
public function gettypelist()
{
return array(array("ffd8ffe1","jpg"),
array("89504e47","png"),
array("47494638","gif"),
array("49492a00","tif"),
array("424d","bmp"),
array("41433130","dwg"),
array("38425053","ps教程d"),
array("7b5c727466","rtf"),
array("3c3f786d6c","xml"),
array("68746d6c3e","html"),
array("44656c69766572792d646174","eml"),
array("cfad12fec5fd746f","dbx"),
array("2142444e","pst"),
array("d0cf11e0","xls/doc"),
array("5374616e64617264204a","mdb"),
array("ff575043","wpd"),
array("252150532d41646f6265","eps/ps"),
array("255044462d312e","pdf"),
array("e3828596","pwl"),
array("504b0304","zip"),
array("52617221","rar"),
array("57415645","wav"),
array("41564920","avi"),
array("2e7261fd","ram"),
array("2e524d46","rm"),
array("000001ba","mpg"),
array("000001b3","mpg"),
array("6d6f6f76","mov"),
array("3026b2758e66cf11","asf"),
array("4d546864","mid"));
}
public static function getfiletype($filename)
{
if(!self::$checkclass) self::$checkclass=new self($filename);
$class=self::$checkclass;
return $class->_getfiletype($filename);
}
}

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