固定高宽：
<script type="text/javascript">
if (/Android (\d+\.\d+)/.test(navigator.userAgent)) {
var version = parseFloat(RegExp.$1);
if (version > 2.3) {
var phoneScale = parseInt(window.screen.width) / 640;
document.write('<meta name="viewport" content="width=640, minimum-scale = ' + phoneScale + ', maximum-scale = ' + phoneScale + ', target-densitydpi=device-dpi">');
} else {
document.write('<meta name="viewport" content="width=640, target-densitydpi=device-dpi">');
}
} else {
document.write('<meta name="viewport" content="width=640, user-scalable=no, target-densitydpi=device-dpi">');
}
</script>