树形结构的组装

1.源数据

[{"Id":1,"Name":"四川","PId":0},{"Id":2,"Name":"成都","PId":1},{"Id":3,"Name":"自贡","PId":1},{"Id":4,"Name":"绵阳","PId":1},{"Id":5,"Name":"成都区-0","PId":2},{"Id":6,"Name":"成都区-1","PId":2},{"Id":7,"Name":"成都区-2","PId":2},{"Id":8,"Name":"成都区-3","PId":2},{"Id":9,"Name":"成都区-4","PId":2},{"Id":10,"Name":"成都区-5","PId":2},{"Id":11,"Name":"成都区-6","PId":2},{"Id":12,"Name":"成都区-7","PId":2},{"Id":13,"Name":"成都区-8","PId":2},{"Id":14,"Name":"成都区-9","PId":2},{"Id":15,"Name":"自贡区-0","PId":3},{"Id":16,"Name":"自贡区-1","PId":3},{"Id":17,"Name":"自贡区-2","PId":3},{"Id":18,"Name":"自贡区-3","PId":3},{"Id":19,"Name":"自贡区-4","PId":3},{"Id":20,"Name":"自贡区-5","PId":3},{"Id":21,"Name":"自贡区-6","PId":3},{"Id":22,"Name":"自贡区-7","PId":3},{"Id":23,"Name":"自贡区-8","PId":3},{"Id":24,"Name":"自贡区-9","PId":3},{"Id":25,"Name":"绵阳区-0","PId":4},{"Id":26,"Name":"绵阳区-1","PId":4},{"Id":27,"Name":"绵阳区-2","PId":4},{"Id":28,"Name":"绵阳区-3","PId":4},{"Id":29,"Name":"绵阳区-4","PId":4},{"Id":30,"Name":"绵阳区-5","PId":4},{"Id":31,"Name":"绵阳区-6","PId":4},{"Id":32,"Name":"绵阳区-7","PId":4},{"Id":33,"Name":"绵阳区-8","PId":4},{"Id":34,"Name":"绵阳区-9","PId":4}]

2.树型结构

{
    "id":2,
    "name":"",
    "pId":1,
    "nodes":[]
}

//元数据
public class Area
{
   public int Id { get; set; }
   public string Name { get; set; } = "";
   public int PId { get; set; }
}
//树结构
public class Area_Tree
{
   public int Id { get; set; }
   public string Name { get; set; } = "";
   public int PId { get; set; }
   public List<Area_Tree> Nodes { get; set; } = new List<Area_Tree>();
}

3.需求

3.1.获得某个节点的树型结构

3.1.1.需求分析

​ 此种需求是最简单的设计,只需要一直递归就行

3.1.2.代码实现

private static Area_Tree GetTree(List<Area_Tree> list, int Id)
{
    var data = list.Where(x => x.Id == Id).Single();
    var trees = list.Where(x => x.PId == Id)
        .ToList();
    //说明找到最底层了
    if (trees.Count == 0)
        return data;
    trees.ForEach(x =>
    {
        //寻找子节点
        GetTree(list, x.Id, ids, nodeids);
    });
    data.Nodes = trees;
    return data;
}

3.2.获得某个节点的所有父级树型结构

3.2.1.需求分析

​ 此需求,分两步走

1. 创建一个集合来存储PId
2. 通过递归一直追查PId，直到PId=0(此处的0是我设定的如果没有上级这PId=0)
3. 找到最上级后,就回到了第一种方案了

3.2.2.代码实现

class Program{
    static main(){
        List<Area_Tree> list=[某个数据源];
        /**{
            "id": 34,
            "name": "绵阳区-9",
            "pId": 4
        	}
        **/
         int id=34;
        Area_Tree tree= GetTree_V2(list, id);
    }
    //找到父节点再找节点
    private static Area_Tree GetTree_V2(List<Area_Tree> list, int id, List<int> ids = null){
            if (ids == null)
                ids = new List<int>();
            ids.Add(id);
            var obj = list.Single(x => x.Id == id);
            if (obj.PId != 0)
                obj = GetTree_V2(list, obj.PId, ids);
            else
                obj.Nodes.Add(GetTree(list, obj.Id, ids));
            return obj;
        }
    //找到当前节点以及子节点
    private static Area_Tree GetTree(List<Area_Tree> list, int Id, List<int> ids = null)
        {
            var data = list.Where(x => x.Id == Id).Single();
            var trees = list.Where(x => x.PId == Id)
                .WhereIF(!ids.IsNullOrCountZore(), x => ids.Contains(x.Id))
                .ToList();
            if (trees.Count == 0)
                return data;
            trees.ForEach(x =>
            {
                GetTree(list, x.Id, ids);
            });
            data.Nodes = trees;
            return data;
        }
}

3.3.获得某个节点的父级与子级树型结构

3.3.1.需求分析

先递归获得所有子节点,放入节点集合。再将此节点ID集合带入递归父节点,再将父节点Id放入节点集合中,递归上级到最高级,开始按照正常流程递归，但只是需要限定一下递归出来的下级必须包含再节点ID集合中.

3.3.2.代码实现

private static Area_Tree GetTree_V2(List<Area_Tree> list, int id, List<int> ids = null)
{
    if (ids == null)
        ids = new List<int>();
    ids.Add(id);
    var obj = list.Single(x => x.Id == id);
    if (obj.PId != 0)
        obj = GetTree_V2(list, obj.PId, ids);
    else
        obj.Nodes.Add(GetTree(list, obj.Id, ids));
    return obj;
}

private static Area_Tree GetTree(List<Area_Tree> list, int Id, List<int> ids = null, List<int> nodeids = null)
{
    if (nodeids == null)
        nodeids = new List<int>();
    var data = list.Where(x => x.Id == Id).Single();
    var trees = list.Where(x => x.PId == Id)
        .WhereIF(!ids.IsNullOrCountZore(), x => ids.Contains(x.Id))
        .ToList();
    nodeids.AddRange(trees.Select(x => x.Id));
    if (trees.Count == 0)
        return data;
    trees.ForEach(x =>
    {
        GetTree(list, x.Id, ids, nodeids);
    });
    data.Nodes = trees;
    return data;
}

int main(){  
    List<Area_Tree> list=[某个数据源];
    /**
    {
      "id": 34,
      "name": "绵阳区-9",
      "pId": 4
    }
    **/
	int id=4;
	var nodelist = new List<int>() { };
    //此方法主要是为了获得所有子节点
    Area_Tree buttontree = GetTree(areas, id, null, nodelist);
    //此方法开始正式组装树
	Area_Tree tree = GetTree_V2(areas, Id, nodelist);  
}