php生成二维码可以有以下几种方式
1.google开放api
例子：
参数说明如下：
http://chart.apis.google.com/chart? ： 调用 Google 图表 API
cht=qr ：选择生产QR码
&chs=100×100 ：尺寸大小
&chld=L|4 ：L代表默认纠错水平； 4代表二维码边界空白大小，可自行调节。
&chl= ：二维码内容
很贴心的是这个api支持get和post
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/
说明：
To install simply include:
qrlib.php for full version (also you have to provide all library files form package plus cache dir)
OR phpqrcode.php for merged version (only one file, but slower and less accurate code because disabled cache and quicker masking configured)
Then use it as follows:
QRcode::png(‘code data text’, ‘filename.png’); // creates file
QRcode::png(‘some othertext 1234′); // creates code image and outputs it directly into browser
例子：
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