PHP取二进制文件头快速判断文件类型

<?php

$files = array('./test.jpg', 'test.png');
$fileTypes = array(
7790 => 'exe',
7784 => 'midi',
8075 => 'zip',
8297 => 'rar',
225216 => 'jpg',
7173 => 'gif',
6677 => 'bmp',
13780 => 'png',
);
foreach($files as $file) {
$fp = fopen($file, 'rb');
$bin = fread($fp, 2); // 只读头两个字节
fclose($fp);
$strInfo = @unpack("C2chars", $bin);
$typeCode = intval($strInfo['chars1'].$strInfo['chars2']);
$fileType = isset($fileTypes[$typeCode]) ? $fileTypes[$typeCode] : 'unknown';
echo $file , ' type : <b>', $fileType, '</b> code : <b>', $fileType, '</b><br />';
}