为listview增加摩擦力方法:
listview.setFriction(ViewConfiguration.getScrollFriction() * 5);
参考:
http://stackoverflow.com/questions/5590001/android-listview-slow-down-scroll-speed
http://developer.android.com/intl/zh-cn/reference/android/widget/AbsListView.html#setFriction(float)