数据结构~树的遍历（Service层和UI层代码）

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问题是这样的，Department表是一个部门表，由DeptId,name和Father组成，它是一种树型的关系，一个部门下可以有多个子部门，同时，它有一个父部门，祖宗部门没有父部门。

以下是测试数据（相当于Data层里取出数据的方法）：

 static List<Department> deptList = new List<Department>
            {
                new Department(1,"根",0),
                new  Department(2,"计算机",1),
                new  Department(3,"英语",1),
                new  Department(4,"C语",2),
                new  Department(5,"VB",2),
                new  Department(6,"公共英语",3),
                new  Department(7,"大学英语",3),
                new  Department(8,"公一级",6),
                new  Department(9,"公二级",6),
                new  Department(10,"公三级",6),
                new  Department(11,"公四级",6),
            };
存放数据源的变量和为变量赋值的方法

#region 加载树，定义存放树的变量

        public static void LoadTree()

        {

            DepartmentTree = deptList;

        }

        public static List<Department> DepartmentTree = null;

#endregion

我们把加载树放在静态构造方法里，保存它只被加载一次就可以了，当然如果希望树自动更新，可以

看文章结尾处

#region 当前类被第一次访问或类被第一次建立时间时加载树
       static Program()
       {
           LoadTree();
       }
#endregion

以下是Service层，进行数据读取的方法:

        #region 树递归Service层

        /// <summary>
        /// 完整树
        /// </summary>
        /// <returns></returns>
        public static Department GetTree()
        {
            return GetTree(Department.RootId);
        }

        /// <summary>
        /// 找到指定ID的树
        /// </summary>
        /// <param name="deptId"></param>
        /// <returns></returns>
        public static Department GetTree(int deptId)
        {
            Department root = new Department();
            root = deptList.Where(i => i.DeptId.Equals(deptId)).SingleOrDefault();
            GetSublCategories(root);
            return root;
        }

        /// <summary>
        ///找到子孙树
        /// </summary>
        /// <param name="department">父对象</param>
        static public void GetSublCategories(Department department)
        {
            department.Sons = DepartmentTree.Where(item =>
                item.FatherId.Equals(department.DeptId) && item.DeptId != Department.RootId).ToList();
            department.Sons.ForEach(item =>
            {
                item.Father = department;
                GetSublCategories(item);
            });

        }
        #endregion

以下是UI层，将树型列表显示在屏幕上的代码：

#region 树递归UI层

        public string GetTreeHtml()

        {

            Department department = GetTree();

            StringBuilder html = new StringBuilder();

            html.Append("<ul id='containerul'>");

            this.GetSubCategory(html, department);

            html.Append("</ul>");

            return html.ToString();

        }

        /// <summary>

        /// 

        /// </summary>

        /// <param name="html">HTML字条串组成树型列表</param>

        /// <param name="department">指定对象</param>

        private void GetSubCategory(StringBuilder html, Department department)

        {

            html.Append("<li id='" + department.DeptId + "'>");

            if (department.Sons != null && department.Sons.Count > 0)

            {

                html.Append("<a href='javascript:void(0)'>");

            }

            else

            {

html.Append("<a href='javascript:void(0)' onclick=\"showDCategoryTree('"

+ department.DeptId + "');\">");

            }

            html.Append("<ins>&nbsp;</ins>");

            html.Append(department.DeptId + "-" + department.Name);

            html.Append("</a>");

            if (department.Sons != null && department.Sons.Count > 0)

            {

                html.Append("<ul>");

                foreach (var item in department.Sons)

                {

                    this.GetSubCategory(html, item);

                }

                html.Append("</ul>");

            }

            html.Append("</li>");

        }

        #endregion

如果你的树（部门）前台显示时不会发生读写操作，可以把取数据方法写在静态构造方法里，就像这样：

 

#region 树递归UI层

        public string GetTreeHtml()

        {

            Department department = GetTree();

            StringBuilder html = new StringBuilder();

            html.Append("<ul id='containerul'>");

            this.GetSubCategory(html, department);

            html.Append("</ul>");

            return html.ToString();

        }

        /// <summary>

        /// 递归所有子树

        /// </summary>

        /// <param name="html">HTML字条串组成树型列表</param>

        /// <param name="department">指定对象</param>

        private void GetSubCategory(StringBuilder html, Department department)

        {

            html.Append("<li id='" + department.DeptId + "'>");

            if (department.Sons != null && department.Sons.Count > 0)

            {

                html.Append("<a href='javascript:void(0)'>");

            }

            else

            {

html.Append("<a href='javascript:void(0)' onclick=\"showDCategoryTree('"

+ department.DeptId + "');\">");

            }

            html.Append("<ins>&nbsp;</ins>");

            html.Append(department.DeptId + "-" + department.Name);

            html.Append("</a>");

            if (department.Sons != null && department.Sons.Count > 0)

            {

                html.Append("<ul>");

                foreach (var item in department.Sons)

                {

                    this.GetSubCategory(html, item);

                }

                html.Append("</ul>");

            }

            html.Append("</li>");

        }

        #endregion

 

OK,这种方法显示出来的树在不关闭浏览器或IIS不重启时，树如果被修改了，它也不会反映到树上的，如果希望改变这种情况，让数的修改实时显示出来，可以加一个事件。

#region 每隔1000毫秒去重新加载树
        static System.Timers.Timer sysTimer = new System.Timers.Timer(1000);
        static void sysTimer_Elapsed(object sender, System.Timers.ElapsedEventArgs e)
        {
            LoadTree();
        }
 #endregion

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