C# Net 树帮助类，树节点帮助类（非递归）

C# Net 树帮助类

C# Net 树节点帮助类

优点：非递归，效率可能更高

 

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---------------------文尾看调用方式------------------

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创建一个新的文件 ITreeNode.cs 并拷贝代码：

 

    /// <summary>
    /// 树节点
    /// </summary>
    public interface ITreeNode<T, Tid>
    {
        /// <summary>
        /// 主键Id
        /// </summary>
        public Tid Id { get; set; }
        /// <summary>
        /// 父Id
        /// </summary>
        public Tid Pid { get; set; }
        /// <summary>
        /// 子节点
        /// </summary>
        public List<T> Children { get; set; }
    }

    /// <summary>
    /// 树节点扩展
    /// </summary>
    public static class TreeNodeEx
    {
        /// <summary>
        /// 转为树结构
        /// </summary>
        /// <param name="treeNodes">树节点</param>
        /// <returns>树节点带子节点（Children）</returns>
        public static List<T> ToTree<T, Tid>(this List<T> treeNodes) where T : ITreeNode<T, Tid>
        {
            if (treeNodes == null || !treeNodes.Any())
                return treeNodes ?? new List<T>();
            if (treeNodes.Any(o => EqualityComparer<Tid>.Default.Equals(o.Id, o.Pid)))
                throw new Exception("存在id和pid相同的数据，无限循环引用");

            var group = treeNodes.GroupBy(x => x.Pid).ToDictionary(x => x.Key, s => s.ToList());

            foreach (var item in treeNodes)
            {
                if (group.ContainsKey(item.Id))
                {
                    var treeNode = group[item.Id];
                    if (treeNode.Any(o => EqualityComparer<Tid>.Default.Equals(o.Id, item.Pid) && EqualityComparer<Tid>.Default.Equals(o.Pid, item.Id)))
                        throw new Exception("存在id和pid交叉引用(如：{Id='我是你',Pid='你是我'} 和 {Id='你是我',Pid='我是你'})");

                    if (item.Children == null)
                        item.Children = new List<T>();

                    item.Children.AddRange(treeNode);
                }
            }

            //查找顶级节点
            var ids = treeNodes.Select(o => o.Id).Distinct();
            var pids = treeNodes.Select(o => o.Pid).Distinct();
            var c = pids.Except(ids);
            return group.Where(o => c.Contains(o.Key)).SelectMany(o => o.Value).ToList();
        }

        /// <summary>
        /// 将指定的id节点转为树结构
        /// </summary>
        /// <param name="treeNodes">树节点</param>
        /// <param name="id">id节点</param>
        /// <returns>树节点带子节点（Children）</returns>
        public static T? ToTree<T, Tid>(this List<T> treeNodes, Tid id) where T : ITreeNode<T, Tid>
        {
            if (treeNodes == null || !treeNodes.Any())
                return default(T);
            if (treeNodes.Any(o => EqualityComparer<Tid>.Default.Equals(o.Id, o.Pid)))
                throw new Exception("存在id和pid相同的数据，无限循环引用");

            var group = treeNodes.GroupBy(x => x.Pid).ToDictionary(x => x.Key, s => s.ToList());

            foreach (var item in treeNodes)
            {
                if (group.ContainsKey(item.Id))
                {
                    var treeNode = group[item.Id];
                    if (treeNode.Any(o => EqualityComparer<Tid>.Default.Equals(o.Id, item.Pid) && EqualityComparer<Tid>.Default.Equals(o.Pid, item.Id)))
                        throw new Exception("存在id和pid交叉引用(如：{Id='我是你',Pid='你是我'} 和 {Id='你是我',Pid='我是你'})");

                    if (item.Children == null)
                        item.Children = new List<T>();

                    item.Children.AddRange(treeNode);
                }
            }

            return treeNodes.FirstOrDefault(o => EqualityComparer<Tid>.Default.Equals(o.Id, id));
        }

        /// <summary>
        /// 转为树节点
        /// </summary>
        /// <param name="treeNodes">树节点</param>
        /// <returns>树节点带子节点（Children）</returns>
        public static List<T> ToTreeNode<T, Tid>(this List<T> treeNodes) where T : ITreeNode<T, Tid>
        {
            if (treeNodes == null || !treeNodes.Any())
                return treeNodes ?? new List<T>();

            List<T> trees = new List<T>();
            foreach (var item in treeNodes)
            {
                trees.Add(item);

                if (item.Children != null && item.Children.Any())
                {
                    var aaa = ToTreeNode<T, Tid>(item.Children);
                    trees.AddRange(aaa);
                }
            }
            return trees;
        }
    }

　　

　　

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     ---------------------开始调用------------------

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1.创建一个类 Info.cs 继承 TreeNodeHelper （也可以直接使用TreeNodeHelper，忽略此步骤）

 

public class City : ITreeNode<City, int>
{
    public string Name { get; set; }

    public int Id { get; set; }
    public int Pid { get; set; }
    public List<City> Children { get; set; }
}

 

2.1 调用（方式一）

 

        List<City> infos = new List<City>()
        {
            new City (){Id=1,Pid=0,Name="重庆" },
            new City (){Id=2,Pid=1,Name="渝中区" },
            new City (){Id=3,Pid=1,Name="北碚区" },
            new City (){Id=4,Pid=2,Name="七星岗" },

            new City (){Id=5,Pid=0,Name="成都" },
            new City (){Id=6,Pid=5,Name="武侯" },
            new City (){Id=7,Pid=5,Name="龙泉" },
        };

        var data = infos.ToTree<City, int>();

 

注：json可复制粘贴到（www.json.cn）中去查看

data效果为（转为json方便查看）：

 

[{"Name":"重庆","Id":1,"Pid":0,"Children":[{"Name":"渝中区","Id":2,"Pid":1,"Children":[{"Name":"七星岗","Id":4,"Pid":2,"Children":null}]},{"Name":"北碚区","Id":3,"Pid":1,"Children":null}]},{"Name":"成都","Id":5,"Pid":0,"Children":[{"Name":"武侯","Id":6,"Pid":5,"Children":null},{"Name":"龙泉","Id":7,"Pid":5,"Children":null}]}]

完成。