iphone能很好的使用onorientationchange事件，但是android的onresize事件即使不旋转也会触发多次。
查了不少资料，最后结论如下：
function orientationChange(){
switch(window.orientation) {
case 0: // Portrait
case 180: // Upside-down Portrait
// Javascript to setup Portrait view
break;
case -90: // Landscape: turned 90 degrees counter-clockwise
case 90: // Landscape: turned 90 degrees clockwise
// Javascript to steup Landscape view
break;
}
}
window.addEventListener("onorientationchange" in window ? "orientationchange" : "resize", orientationChange, false);