android 代码生成selector drawable

public static StateListDrawable makeSelector(Context context, int idNormal, int idPressed, int idFocused) {
    StateListDrawable bg = new StateListDrawable();
    Drawable normal = context.getResources().getDrawable(idNormal);
    Drawable pressed = context.getResources().getDrawable(idPressed);
    Drawable focused = context.getResources().getDrawable(idFocused);
    bg.addState(new int[]{android.R.attr.state_pressed,}, pressed);
    bg.addState(new int[]{android.R.attr.state_focused}, focused);
    bg.addState(new int[]{}, normal);
    return bg;
}

注意： 1.normal state要在最后add
      2.使用button测试,ImageView 需要设置clickable为true