https://www.cnblogs.com/wangyinlon/p/11679180.html
c#.NET中各种递归
最近工作中涉及到菜单,各种递归.总结了2种.
按父级子级生成树
public async Task<List<ResourceDirectorysListTreeDto>> GetTreeByParentId(long id, int getChildCount = 0) { var menuAll = _ResourceDirectorysRepository.GetAll().Where(zz => zz.IsDeleted == false); var menuRoot = await _ResourceDirectorysRepository.GetAll().Where(zz => zz.ParentId == id && zz.IsDeleted == false).ToListAsync(); var menuList = ObjectMapper.Map<List<ResourceDirectorysListTreeDto>>(menuRoot); // 为一级菜单设置子菜单,getChild是递归调用的 foreach (var item in menuList) { item.Child = GetChild(item.Id, menuAll.ToList(), 1, getChildCount); } return menuList; } private List<ResourceDirectorysListTreeDto> GetChild(long id, List<EntityDesign.Resourses.ResourceDirectorys> menuAll, int excouteCout, int getChildCount) { if (getChildCount > 0 && excouteCout > getChildCount) { return null; } //子菜单 List<ResourceDirectorysListTreeDto> childList = new List<ResourceDirectorysListTreeDto>(); // 遍历所有节点,将父菜单id与传过来的id比较 var list = menuAll.Where(x => x.ParentId == id).ToList(); if (!list.Any()) { return null; } foreach (var item in list) { if (item.ParentId == id) { childList.Add(new ResourceDirectorysListTreeDto { Id = item.Id, ParentId = item.ParentId, Name = item.Name, IndexLevel = item.IndexLevel }); } } // 把子菜单的子菜单再循环一遍 foreach (var item in childList) { item.Child = GetChild(item.Id, menuAll, excouteCout + 1, getChildCount); } // 递归退出条件 if (childList.Count == 0) { return null; } return childList; }
按父级子级生成List
public async Task<List<ResourceDirectorysListDto>> GetAllListByParentId(long id) {</span><span style="color: rgba(0, 0, 255, 1)">var</span> menuRoot = <span style="color: rgba(0, 0, 255, 1)">await</span> _ResourceDirectorysRepository.GetAll().Where(zz => zz.ParentId == id && zz.IsDeleted == <span style="color: rgba(0, 0, 255, 1)">false</span><span style="color: rgba(0, 0, 0, 1)">).ToListAsync(); </span><span style="color: rgba(0, 0, 255, 1)">var</span> menuList = ObjectMapper.Map<List<ResourceDirectorysListDto>><span style="color: rgba(0, 0, 0, 1)">(menuRoot); </span><span style="color: rgba(0, 128, 0, 1)">//</span><span style="color: rgba(0, 128, 0, 1)"> 为一级菜单设置子菜单,getChild是递归调用的</span> <span style="color: rgba(0, 0, 255, 1)">var</span> temp = <span style="color: rgba(0, 0, 255, 1)">new</span> List<ResourceDirectorysListDto><span style="color: rgba(0, 0, 0, 1)">(); </span><span style="color: rgba(0, 0, 255, 1)">foreach</span> (<span style="color: rgba(0, 0, 255, 1)">var</span> item <span style="color: rgba(0, 0, 255, 1)">in</span><span style="color: rgba(0, 0, 0, 1)"> menuList) { temp.Add(item); </span><span style="color: rgba(0, 0, 255, 1)">var</span> t =<span style="color: rgba(0, 0, 0, 1)"> GetChild2(item.Id); </span><span style="color: rgba(0, 0, 255, 1)">if</span> (t != <span style="color: rgba(0, 0, 255, 1)">null</span><span style="color: rgba(0, 0, 0, 1)">) { item.IsParent </span>= <span style="color: rgba(0, 0, 255, 1)">true</span><span style="color: rgba(0, 0, 0, 1)">; temp.AddRange(t); } </span><span style="color: rgba(0, 0, 255, 1)">else</span><span style="color: rgba(0, 0, 0, 1)"> { item.IsParent </span>= <span style="color: rgba(0, 0, 255, 1)">false</span><span style="color: rgba(0, 0, 0, 1)">; } } </span><span style="color: rgba(0, 0, 255, 1)">return</span><span style="color: rgba(0, 0, 0, 1)"> temp; } </span><span style="color: rgba(0, 0, 255, 1)">private</span> List<ResourceDirectorysListDto> GetChild2(<span style="color: rgba(0, 0, 255, 1)">long</span><span style="color: rgba(0, 0, 0, 1)"> id) { </span><span style="color: rgba(0, 128, 0, 1)">//</span><span style="color: rgba(0, 128, 0, 1)">子菜单</span> List<ResourceDirectorysListDto> childList = <span style="color: rgba(0, 0, 255, 1)">new</span> List<ResourceDirectorysListDto><span style="color: rgba(0, 0, 0, 1)">(); </span><span style="color: rgba(0, 128, 0, 1)">//</span><span style="color: rgba(0, 128, 0, 1)"> 遍历所有节点,将父菜单id与传过来的id比较</span> <span style="color: rgba(0, 0, 255, 1)">var</span> list = _ResourceDirectorysRepository.GetAll().Where(x => x.ParentId ==<span style="color: rgba(0, 0, 0, 1)"> id).ToList(); </span><span style="color: rgba(0, 0, 255, 1)">if</span> (!<span style="color: rgba(0, 0, 0, 1)">list.Any()) { </span><span style="color: rgba(0, 0, 255, 1)">return</span> <span style="color: rgba(0, 0, 255, 1)">null</span><span style="color: rgba(0, 0, 0, 1)">; } </span><span style="color: rgba(0, 0, 255, 1)">foreach</span> (<span style="color: rgba(0, 0, 255, 1)">var</span> item <span style="color: rgba(0, 0, 255, 1)">in</span><span style="color: rgba(0, 0, 0, 1)"> list) { </span><span style="color: rgba(0, 0, 255, 1)">if</span> (item.ParentId ==<span style="color: rgba(0, 0, 0, 1)"> id) { </span><span style="color: rgba(0, 0, 255, 1)">var</span> z = <span style="color: rgba(0, 0, 255, 1)">new</span><span style="color: rgba(0, 0, 0, 1)"> ResourceDirectorysListDto { Id </span>=<span style="color: rgba(0, 0, 0, 1)"> item.Id, ParentId </span>=<span style="color: rgba(0, 0, 0, 1)"> item.ParentId, Name </span>=<span style="color: rgba(0, 0, 0, 1)"> item.Name, }; childList.Add(z); </span><span style="color: rgba(0, 0, 255, 1)">var</span> t =<span style="color: rgba(0, 0, 0, 1)"> GetChild2(item.Id); </span><span style="color: rgba(0, 0, 255, 1)">if</span> (t != <span style="color: rgba(0, 0, 255, 1)">null</span><span style="color: rgba(0, 0, 0, 1)">) { z.IsParent </span>= <span style="color: rgba(0, 0, 255, 1)">true</span><span style="color: rgba(0, 0, 0, 1)">; childList.AddRange(t); } </span><span style="color: rgba(0, 0, 255, 1)">else</span><span style="color: rgba(0, 0, 0, 1)"> { z.IsParent </span>= <span style="color: rgba(0, 0, 255, 1)">false</span><span style="color: rgba(0, 0, 0, 1)">; } } } </span><span style="color: rgba(0, 128, 0, 1)">//</span><span style="color: rgba(0, 128, 0, 1)"> 递归退出条件</span> <span style="color: rgba(0, 0, 255, 1)">if</span> (childList.Count == <span style="color: rgba(128, 0, 128, 1)">0</span><span style="color: rgba(0, 0, 0, 1)">) { </span><span style="color: rgba(0, 0, 255, 1)">return</span> <span style="color: rgba(0, 0, 255, 1)">null</span><span style="color: rgba(0, 0, 0, 1)">; } </span><span style="color: rgba(0, 0, 255, 1)">return</span><span style="color: rgba(0, 0, 0, 1)"> childList; }</span></pre>