1.implements ViewTreeObserver.OnGlobalLayoutListener｛｝
2.mContentView.getViewTreeObserver().addOnGlobalLayoutListener(this)
3.@Override
public void onGlobalLayout() {｝
4.mContentView.getViewTreeObserver().removeOnGlobalLayoutListener(this);
原文：http://www.cnblogs.com/dubo-/p/7856172.html