activity：
DisplayMetrics dm = new DisplayMetrics();
this.getWindowManager().getDefaultDisplay().getMetrics(dm);
sW = dm.widthPixels;
sH = dm.heightPixels;
service：
DisplayMetrics dm = new DisplayMetrics();
dm = getResources().getDisplayMetrics();
int screenWidth = dm.widthPixels;
int screenHeight = dm.heightPixels;