按照当前页的url，生成二维码扫图
<style type="text/css">
.eweima{
width:200px;
height:200px;
margin:auto;
}
</style>
<div class="eweima">
<script type="text/javascript">
document.write("<img src=\"https://chart.googleapis.com/chart?cht=qr&chs=500x500&choe=UTF-8&chld=L|2&chl="); title=""
document.write(window.location.href);
document.write("\" width=\"200\" height=\"200\" alt=\"二维码\"/>");
</script>
</div>