android - Rotating refresh button -

i have refresh button defined in layout file follow:

<imagebutton       android:id="@+id/btn_refresh_assets"       android:layout_width="fill_parent"       android:layout_height="wrap_content"       android:layout_gravity="center"       android:onclick="onclick"       android:src="@drawable/ic_menu_refresh" /> 

when button clicked, asynctask called load data webservice. want rotate refresh icon until load complete!!! there guidlines doing in actionbar button placed in middle of page , not in actionbar.

here code

animation animation = new rotateanimation(0.0f, 360.0f,                 animation.relative_to_self, 0.5f, animation.relative_to_self,                 0.5f);         animation.setrepeatcount(-1);         animation.setduration(2000); 

create animation

before starting service attach animation imageview below

((imageview)findviewbyid(r.id.btn_refresh_assets)).setanimation(animation); 

and when service ends

((imageview)findviewbyid(r.id.btn_refresh_assets)).clearanimation();