1.google开放api
$urlToEncode="http://bbs.lewanchina.com ";
generateQRfromGoogle($urlToEncode);
function generateQRfromGoogle($chl,$widhtHeight ='150',$EC_level='L',$margin='0')
{
?$url = urlencode($url);
?echo '<img src="http://chart.apis.google.com/chart?chs='.$widhtHeight.'x'.$widhtHeight.'&cht=qr&chld='.$EC_level.'|'.$margin.'&chl='.$chl.' " alt="QR code" widhtHeight="'.$size.'" widhtHeight="'.$size.'"/>';
}

?

2.php类库PHP QR Code
PHP QR Code is open source (LGPL) library for generating QR Code,
2-dimensional barcode. Based on libqrencode C library,
provides API for creating QR Code barcode images (PNG, JPEG thanks to GD2).
Implemented purely in PHP, with no external dependencies (except GD2 if needed).

地址：http://phpqrcode.sourceforge.net/
下载：http://sourceforge.net/projects/phpqrcode/

3.libqrencode

地址：http://fukuchi.org/works/qrencode/index.en.html
php支持请参考：http://hirokawa.netflowers.jp/entry/4900/

4.QRcode Perl CGI & PHP scripts
地址：http://www.swetake.com/qr/qr_cgi.html