java.lang.Object
       android.graphics.drawable.Drawable
Known Direct Subclasses
   BitmapDrawable, ClipDrawable, ColorDrawable, DrawableContainer, GradientDrawable, InsetDrawable, LayerDrawable, NinePatchDrawable, PictureDrawable,        RotateDrawable, ScaleDrawable, ShapeDrawable
Known Indirect Subclasses
  AnimationDrawable, LevelListDrawable, PaintDrawable, StateListDrawable, TransitionDrawable

    这里 有一些常用xml表示的样式可以用代码来实现，比如 selector ，可以使用stateListDrawable来代码实现

   连接在此：http://developer.android.com/reference/android/graphics/drawable/Drawable.html

   textView的文字点击效果，可以使用  ColorStateList来实现

   连接在此:

   http://developer.android.com/reference/android/content/res/ColorStateList.html