Fragment在ViewPager中判断显示还是隐藏

注意只有在ViewPager中才会调用此方法

@Override  
public void setUserVisibleHint(boolean isVisibleToUser) {  
  super.setUserVisibleHint(isVisibleToUser);  
  if (isVisibleToUser) {  
  //相当于activity的onResume  
  } else {  
  //相当于activity的onPause  
  }  
}