143.根据文件头判断类型

function getFileType($filename) {
if (!file_exists($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 = array(
array("FFD8FFE1","jpg"),
array("FFD8FFE0","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")
);

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 'other';
}