1，首先写了一个辅助的Model（CityEasyTree EasyUI Tree需要的的数据格式要符合json。标明 EasyUI Tree的API 中常用属性）
1 public class CityEasyTree 2 ????{ 3 ???????/// <summary> 4 ???????/// id 5 ???????/// </summary> 6 ????????public int id { get; set; } 7 ???????/// <summary> 8 ???????/// 节点名称 9 ???????/// </summary>10 ????????public string text { get; set; }11 ???????/// <summary>12 ???????/// 是否展开13 ???????/// </summary>14 ????????public string state { get; set; }15 ???????/// <summary>16 ???????/// 图标17 ???????/// </summary>18 ????????public string iconCls { get; set; }19 ???????/// <summary>20 ???????/// 子节点集合21 ???????/// </summary>22 ????????public List<CityEasyTree> ?children { get; set; }23 ????????public CityEasyTree( )24 ????????{25 ????????????this.state = "open";26 ????????????this.children = new List<CityEasyTree>();27 ????????}28 ????????/// <summary>29 ????????/// 常用构造函数30 ????????/// </summary>31 ????????public CityEasyTree(string id, string text, string iconCls = "", string state = "open", List<CityEasyTree> ?listChildren =null)32 ????????????: this()33 ????????{34 ????????????this.id =int.Parse(id);35 ????????????this.text = text;36 ????????????this.state = state;37 ????????????this.iconCls = iconCls;38 ????????????this.children = listChildren;39 ????????}40 ???????/// <summary>41 ????????/// 常用构造函数42 ????????/// </summary>43 ????????public CityEasyTree(int id, string text, string iconCls = "", string state = "open")44 ????????????: this()45 ????????{46 ????????????this.id = id;47 ????????????this.text = text;48 ????????????this.state = state;49 ????????????this.iconCls = iconCls;50 ????????}51 ????}CityEasyTree 说明：一个简单的实现（没有实现attributes，url）
- id：节点ID，对加载远程数据很重要。
- text：显示节点文本。
- state：节点状态，‘open‘ 或 ‘closed‘，默认：‘open‘。在设置为‘closed‘的时候，当前节点的子节点将会从远程服务器加载他们。
- attributes: 被添加到节点的自定义属性。（Url属性就在这个里面，用Dictionary可以方便的扩展attribute。）
- children: 一个节点数组声明了若干节点。（这个是子节点，它拥有所有的父节点属性）
符合Tree 的json数据格式查看EasyuI API （ 官网文档:http://www.jeasyui.net/plugins/185.html ）
2，从数据库得到的DataTable转成成EasyUI所需要的对象结合，下面也是本文的核心代码。
/// <summary> ???????/// 获取父节点 ???????/// </summary> ???????/// <param name="parentId"></param> ???????/// <returns></returns> ???????public List<CityEasyTree> GetTreeParentList(int parentId) ???????{ ???????????List<CityEasyTree> treeParentNodeList = new List<CityEasyTree>(); ???????????//从数据库获取相应数据 ?????????????List<City> list = new CityBLL().GetCityByParentId(parentId); ???????????foreach (City info in list) ???????????{ ???????????????string infoName = info.CityName; ???????????????treeParentNodeList.Add(new CityEasyTree(info.PkId.ToString(), info.CityName, "open", "icon-user", GetTreeChildNodeList(info.PkId))); ?????????????????????????} ???????????return treeParentNodeList; ???????} ???????/// <summary> ???????/// 获取所有的子节点（递归） ???????/// </summary> ???????/// <param name="parentId"></param> ???????/// <returns></returns> ???????public List<CityEasyTree> GetTreeChildNodeList(int parentId) ???????{ ???????????List<CityEasyTree> treeChildNodeList = new List<CityEasyTree>(); ???????????//从数据库获取相应数据 ?????????????List<City> list = new CityBLL().GetCityByParentId(parentId); ???????????foreach (City info in list) ???????????{ ???????????????string infoName = info.CityName; ???????????????treeChildNodeList.Add(new CityEasyTree(info.PkId.ToString(), info.CityName, "open", "icon-user", GetTreeChildNodeList(info.PkId))); ????????????} ???????????return treeChildNodeList; ???????} ???????/// <summary> ???????/// json 数据装换 ???????/// </summary> ???????/// <param name="obj"></param> ???????/// <returns></returns> ???????protected string ToJson(object obj) ???????{ ???????????string jsonData = (new JavaScriptSerializer()).Serialize(obj); ???????????return jsonData; ???????}3，在Controller中调用GetTreeParentList方法，获得对象集合，然后把集合转变成json对象（提示一下，后台所有的转换，都是为了返回EasyUI所需要的Json格式。需要注意的是：Json格式中，所有属性的字母都是小写的，所以在封装JsonTree对象时记得小写,避免不必要的麻烦。）
/// <summary> ???????/// ??获取treejson 数据 ?post ?GetTreeJson ???????/// </summary> ???????/// <param name="deptId"></param> ???????/// <returns></returns> ???????public ActionResult GetTreeJson(int parentId) ???????{ ???????????List<CityEasyTree> treeList = new List<CityEasyTree>(); ???????????treeList = GetTreeParentList(parentId); ???????????string json = ToJson(treeList); ???????????reurn Content(json.ToLower()); ???????}4，前台界面就比较简单了（根据EasyUI API 初始一个tree 官网文档:http://www.jeasyui.net/plugins/185.html 需要引用相关js这里就不说了）
<ul id="tt" class="easyui-tree"> ??????</ul><script type="text/javascript"> ???$(function () { ???????LoadData(0); ???}); ???function LoadData(parentId) { ???????$(‘#tt‘).tree({ ???????????url: "/AricleCatetary/GetUserTreeJson?parentId=" + parentId, ???????}); ???}</script>5，实现效果如下图。
6，最后附上 脚本，核心源码和开发过程中需要的工具（链接: https://pan.baidu.com/s/1dFk1YO5 密码: k3zk）。
还要感谢 "身未动、心已远"（http://www.cnblogs.com/yonex/p/3379362.html） 博主的技术支持
jQuery EasyUI 数据树控件（Tree）的简单使用实例
原文地址：http://www.cnblogs.com/blogsxyz/p/8005010.html