Flex中如何利用openItems属性，检测当前Tree的哪一个节点被展开

main.mxml

1. <?xml version="1.0" encoding="utf-8"?>
2. <mx:Applicationxmlns:mx="http://www.adobe.com/2006/mxml"
3. layout="vertical"
4. verticalAlign="middle"
5. backgroundColor="white">
7. <mx:Script>
8. <![CDATA[
9. import mx.events.TreeEvent;
10. import mx.utils.ObjectUtil;
12. private function tree_openItems_change(evt:TreeEvent):void {
13. /* Set the array and let binding do the real work. */
14. openItemArr = tree.openItems as Array;
15. }
16. ]]>
17. </mx:Script>
19. <mx:Arrayid="openItemArr" />
21. <mx:XMLid="xmlDP">
22. <node>
23. <nodelabel="1.a" />
24. <nodelabel="1.b" />
25. <nodelabel="1.c">
26. <nodelabel="1.c.i" />
27. <nodelabel="1.c.ii" />
28. <nodelabel="1.c.iii" />
29. <nodelabel="1.c.iv" />
30. <nodelabel="1.c.v" />
31. </node>
32. <nodelabel="1.d" />
33. <nodelabel="1.e">
34. <nodelabel="1.e.i" />
35. <nodelabel="1.e.ii" />
36. <nodelabel="1.e.iii">
37. <nodelabel="1.e.iii.A" />
38. </node>
39. <nodelabel="1.e.iv" />
40. </node>
41. <nodelabel="1.f" />
42. </node>
43. </mx:XML>
45. <mx:ApplicationControlBardock="true">
46. <mx:Labeltext="Tree openItems length: {openItemArr.length}" />
47. </mx:ApplicationControlBar>
49. <mx:HDividedBoxwidth="100%">
50. <mx:Treeid="tree"
51. dataProvider="{xmlDP}"
52. labelField="@label"
53. showRoot="false"
54. width="50%"
55. rowCount="8"
56. itemOpen="tree_openItems_change(event);"
57. itemClose="tree_openItems_change(event);"/>
59. <mx:Listid="list"
60. dataProvider="{openItemArr}"
61. labelField="@label"
62. width="50%"
63. height="100%"/>
65. <mx:TextAreaid="textArea"
66. editable="false"
67. text="{ObjectUtil.toString(openItemArr)}"
68. width="50%"
69. height="100%"/>
70. </mx:HDividedBox>
72. </mx:Application>