安卓关于不能完全去除dialog的背景问题的解决方案

@Override
public void onStart() {
super.onStart();
View view=getDialog().getWindow().getDecorView();
clearBackground(view);
}
private void clearBackground(View view)
{
if (!(view instanceof ViewGroup)) {
view.setBackground(null);
return;
}
if(view.getId()==R.id.parentId)
return;
for (int i=0;i<((ViewGroup) view).getChildCount();i++)
{
view.setBackground(null);
clearBackground(((ViewGroup) view).getChildAt(i));
}
}