Flex tree 展开任意想展开的节点

mytree.selectedIndex = 0;
mytree.expandItem(mytree.selectedItem,true);
mytree.expandChildrenOf(mytree.selectedItem,true);
//
for each (var treeItem:XML in xml){
if (treeItem.@name == "巡查维护"){
mytree.expandItem(treeItem,true);
break;
}
}
//循环最后一层节点的数据，此节点就是应选择的节点数据，可根据层级关系来设置选中那一节点
for each (var treeItem:XML in xml.children()){
if (treeItem.@name == "闸站"){
mytree.expandItem(treeItem,true);
break;
}

}