关于flex中tree的事件，展开事件

（1）tree点击事件public function handleList(ev:ResultEvent)
{
sourceList=ev.result as ArrayCollection;
}
private function tree_itemClick(evt:ListEvent):void {
var item:Object = Tree(evt.currentTarget).selectedItem;
if (pmtree.dataDescriptor.isBranch(item)) {
pmtree.expandItem(item, !pmtree.isItemOpen(item), true);
}
Alert.show(item["id"].toString());
}

 
(2) 自动展开
Tree. openItems=数据源;  即可
(3) Flex中如何利用dataDescriptor和labelFunction属性，以及hasChildren()和getChildren()函数设置Tree中包含子节点个数。1. <?xml version="1.0" encoding="utf-8"?>
2. <mx:Application xmlns:mx="http://www.adobe.com/2006/mxml"
3. layout="vertical"
4. verticalAlign="middle"
5. backgroundColor="white">
6.
7. <mx:Script>
8. <!--[CDATA[
9. private function tree_labelFunc(item:XML):String {
10. var label:String = item.@label;
11. if (tree.dataDescriptor.hasChildren(item)) {
12. label += " (" + tree.dataDescriptor.getChildren(item).length + ")";
13. }
14. return label;
15. }
16. ]]-->
17. </mx:Script>
18.
19. <mx:XML id="treeDP">
20. <root>
21. <node label="i) One" />
22. <node label="i) Two" />
23. <node label="i) Three" />
24. <node label="i) Four">
25. <node label="ii) One" />
26. <node label="ii) Two" />
27. <node label="ii) Three">
28. <node label="iii) One" />
29. <node label="iii) Two" />
30. </node>
31. <node label="ii) Four" />
32. </node>
33.