背景
将一个具有ChildCode(子节点)和ParentCode(父节点)的list集合转换成树状结构。
生成数据基本格式，如下图：
最终展示样式，如下图：
（注:如果你对样式没要求，可以使用layui的树形组件，简单方便-https://www.layui.com/demo/tree.html）
有两种转换方式，一种是普通的递归，一种是双层循环。数据量非很大的情况下，递归的效率相比双层循环来说，效率高一些。
注：不要循环调用数据库，最好将数据根据条件全部查询出来，然后进行处理。
准备工作
声明一个Model类：
public class TreeNode
{
/// <summary>
/// 子id
/// </summary>
public string Id { get; set; }
/// <summary>
/// 父id
/// </summary>
public string ParentId { get; set; }
/// <summary>
/// 名称
/// </summary>
public string Name { get; set; }
/// <summary>
/// 子节点
/// </summary>
public List<TreeNode> Children { get; set; }
/// <summary>
/// 无参构造函数
/// </summary>
public TreeNode()
{
Children = new List<TreeNode>();
}
/// <summary>
/// 有参构造函数
/// </summary>
/// <param name="id">子id</param>
/// <param name="name">名称</param>
/// <param name="parentId">父id</param>
public TreeNode(string id, string name, string parentId)
{
this.Id = id;
this.Name = name;
this.ParentId = parentId;
Children = new List<TreeNode>();
}
/// <summary>
/// 有参构造函数
/// </summary>
/// <param name="id">子id</param>
/// <param name="name">名称</param>
/// <param name="parent">父节点</param>
public TreeNode(string id, string name, TreeNode parent)
{
this.Id = id;
this.Name = name;
this.ParentId = parent.Id;
Children = new List<TreeNode>();
}
}
生成一个转换前的list集合：
TreeNode treeNode1 = new TreeNode("1", "山东", "0");
TreeNode treeNode2 = new TreeNode("2", "北京", "0");
TreeNode treeNode3 = new TreeNode("3", "历下区", treeNode1);
TreeNode treeNode4 = new TreeNode("4", "高新区", treeNode1);
TreeNode treeNode5 = new TreeNode("5", "历城区", treeNode1);
TreeNode treeNode6 = new TreeNode("6", "甸柳庄", treeNode3);
TreeNode treeNode7 = new TreeNode("7", "济南长途汽车站东站", treeNode6);
TreeNode treeNode8 = new TreeNode("8", "朝阳区", treeNode2);
TreeNode treeNode9 = new TreeNode("9", "海淀区", treeNode2);
TreeNode treeNode10 = new TreeNode("10", "金盏乡", treeNode8);
List<TreeNode> list = new List<TreeNode>();
list.Add(treeNode1);
list.Add(treeNode2);
list.Add(treeNode3);
list.Add(treeNode4);
list.Add(treeNode5);
list.Add(treeNode6);
list.Add(treeNode7);
list.Add(treeNode8);
list.Add(treeNode9);
list.Add(treeNode10);
递归方式
调用方式：
List<TreeNode> trees1 = TreeHelper.BulidTreeByRecursive(list, new List<TreeNode>(), "0");
实现代码：
/// <summary>
/// 使用递归方法建树
/// </summary>
public static List<TreeNode> BulidTreeByRecursive(List<TreeNode> treeNodes, List<TreeNode> resps, string pID)
{
resps = new List<TreeNode>();
List<TreeNode> tempList = treeNodes.Where(c => c.ParentId == pID).ToList();
for (int i = 0; i < tempList.Count; i++)
{
TreeNode node = new TreeNode();
node.Id = tempList[i].Id;
node.ParentId = tempList[i].ParentId;
node.Name = tempList[i].Name;
node.Children = BulidTreeByRecursive(treeNodes, resps, node.Id);
resps.Add(node);
}
return resps;
}
双层循环
调用方式：
List<TreeNode> trees = TreeHelper.BulidTree(list);
实现代码：
/// <summary> /// 双层循环 /// </summary> /// <param name="treeNodes"></param> /// <returns></returns> public static List<TreeNode> BulidTree(List<TreeNode> treeNodes) { try { List<TreeNode> trees = new List<TreeNode>(); foreach (var treeNode in treeNodes) { if ("0" == (treeNode.ParentId)) { trees.Add(treeNode); } foreach (var it in treeNodes) { if (it.ParentId == treeNode.Id) { treeNode.Children.Add(it); } } } return trees; } catch (Exception ex) { throw ex; } }
代码下载
百度云盘：链接：https://pan.baidu.com/s/1XLP7kl3RuadT2y12VmOHeQ 提取码：6mlj
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