在线预览&代码实现
重点：

1. 整棵目录树的实现，通过嵌套完成，主要在于对treeItem.html的递归使用

    <script type="text/ng-template" id="treeView.html">
        <ul>
            <li ng-repeat="item in treeData.children" ng-include="'treeItem.html'"></li>
        </ul>
    </script>
   
    <script type="text/ng-template" id="treeItem.html">
        <span class="color-indictor" ng-class="{'leaf-node': isLeaf(item), 'expand-node': !isLeaf(item) && item.isExpand, 'unexpand-node': !isLeaf(item) && !item.isExpand}" ng-click="toggleExpandStatus(item)"></span>
        <span></span>
        <ul ng-if="!isLeaf(item)" ng-show="item.isExpand">
            <li ng-repeat="item in item.children" ng-include="'treeItem.html'"></li>
        </ul>
    </script>
   

2. 点击展开/关闭目录树
   通过ng-show对item.expand进行判断，点击item时切换其expand参数，完成目录树的打开与关闭

参考链接：
Angular实现递归指令 - Tree View
引入ng-include和模板ng-template