PHP Header下载文件在IE文件名中文乱码问题

解决PHP Header下载文件在IE文件名中文乱码有两种常见的，一种是是把页面编码改成utf8，另一种是对中文url进入urlencode编码，根据UA检测，区别下载，就可以解决了

$filename = "中文.txt";
$ua = $_SERVER["HTTP_USER_AGENT"];
$encoded_filename = urlencode($filename);
$encoded_filename = str_replace("+", "%20", $encoded_filename);
header('Content-Type: application/octet-stream');
if (preg_match("/MSIE/", $ua)) {
    header('Content-Disposition: attachment; filename="' . $encoded_filename . '"');
} else if (preg_match("/Firefox/", $ua)) {
    header('Content-Disposition: attachment; filename*="utf8''' . $filename . '"');
} else {
    header('Content-Disposition: attachment; filename="' . $filename . '"');
}