Android開發教程：代碼實現StateListDrawable

優點：靈活，減少xml的編寫。

用途：動態設置Button、ImageView等組件在不同狀態下的背景/前景顯示效果。

參考：

[AndroidOpenSource]\frameworks\base\core\java\android\view\view.xml

[AndroidOpenSource]\frameworks\base\core\res\res\values\public.xml

代碼如下：

1. /** 設置Selector。 */
2. public static StateListDrawable newSelector(Context context, int idNormal, int idPressed, int idFocused,
3. int idUnable) {
4. StateListDrawable bg = new StateListDrawable();
5. Drawable normal = idNormal == -1 ? null : context.getResources().getDrawable(idNormal);
6. Drawable pressed = idPressed == -1 ? null : context.getResources().getDrawable(idPressed);
7. Drawable focused = idFocused == -1 ? null : context.getResources().getDrawable(idFocused);
8. Drawable unable = idUnable == -1 ? null : context.getResources().getDrawable(idUnable);
9. // View.PRESSED_ENABLED_STATE_SET
10. bg.addState(new int[] { android.R.attr.state_pressed, android.R.attr.state_enabled }, pressed);
11. // View.ENABLED_FOCUSED_STATE_SET
12. bg.addState(new int[] { android.R.attr.state_enabled, android.R.attr.state_focused }, focused);
13. // View.ENABLED_STATE_SET
14. bg.addState(new int[] { android.R.attr.state_enabled }, normal);
15. // View.FOCUSED_STATE_SET
16. bg.addState(new int[] { android.R.attr.state_focused }, focused);
17. // View.WINDOW_FOCUSED_STATE_SET
18. bg.addState(new int[] { android.R.attr.state_window_focused }, unable);
19. // View.EMPTY_STATE_SET
20. bg.addState(new int[] {}, normal);
21. return bg;
22. }