本文實例為大家分享了無限級聯下拉列表框的的實現方法，具體內容如下
可能有一個樹型結構的表，它可能有ID,Name,ParentID,Level等字段，下面要實現的就是從一級節點開始，一級一級的列出來，并以
下拉列表框的形式體現出來，就像是Ｎ級聯動。
效果圖：
兩個問題：
１、建立操作時的聯動，它不需要進行自動綁定
２、編輯操作時的聯運，它需要根據子節點，逐級自己綁定到父節點，直到根
實現：
ＪＳ代碼
<script type="text/javascript"> function areaOnSelect(obj) { var res = ''; $.ajax({ url: '@Url.Action("GetSubTree")', type: 'GET', data: { parentId: obj.value }, success: function (msg) { $(obj).nextAll().remove(); res = "<select name='Sub' onchange='areaOnSelect(this)'>"; res += "<option value=''>請選擇</option>"; $.each(msg, function (i, item) { res += "<option value='" + item["ID"] + "'>" + item["Name"] + "</option>"; }); res += "</select>"; if ($(res).find("option").size() > 1) $(obj).after(res); } }); }</script>Ｃ#代碼：
#region 樹型結構相關 /// <summary> /// 遞歸找老祖宗 /// </summary> /// <param name="father"></param> void GetFather(SubItem father) { if (father != null) { father.Parent = _subList.FirstOrDefault(i => i.ID == father.ParentID); GetFather(father.Parent); } } /// <summary> /// 弟妹找子孫 /// </summary> /// <param name="father">父對象</param> void getSons(SubItem father) { if (father != null) { father.Sons = _subList.Where(item => item.ParentID.Equals(father.ID)).ToList(); father.Sons.ForEach(item => { item.Parent = father; getSons(item); }); } } #endregionＣ#拼接下拉列表框相關：
/// <summary> /// 遞歸得到它的所有祖宗以selectlist的形式進行拼接 /// </summary> /// <param name="son"></param> /// <param name="sbr"></param> void getSelectList(SubItem son, StringBuilder sbr) { StringBuilder inSbr = new StringBuilder(); if (son != null) { if (son.ParentID == 0) inSbr.Append("<select name='Parent' onchange = 'areaOnSelect(this)' >"); else inSbr.Append("<select name='Sub'>"); GetCommon_CategoryByLevel(son.Level).ToList().ForEach(i => { if (i.ID == son.ID) inSbr.Append("<option value='" + i.ID + "' selected='true'>" + i.Name + "</option>"); else inSbr.Append("<option value='" + i.ID + "'>" + i.Name + "</option>"); }); inSbr.Append("</select>"); sbr.Insert(0, inSbr); getSelectList(son.Parent, sbr); } }Ｃ#得到同一深度的節點（同輩節點）相關：
/// <summary> /// 得到指定深度的列表 /// </summary> /// <param name="level"></param> /// <returns></returns> public List<SubItem> GetCommon_CategoryByLevel(int level) { var linq = from data1 in _subList join data2 in _subList on data1.ParentID equals data2.ID into list select new SubItem { ID = data1.ID, Level = data1.Level, Name = data1.Name, Parent = list.FirstOrDefault(), ParentID = data1.ParentID, }; return linq.Where(i => i.Level.Equals(level)).ToList(); }ＭＶＣ頁面action相關：
public ActionResult Category(int? id) { ViewData["Parent"] = new SelectList(_subList.Where(i => i.ID == (id ?? 0)), "ID", "Name", id ?? 1); SubItem current = _subList.FirstOrDefault(i => i.ID == (id ?? 1)); GetFather(current); StringBuilder sbr = new StringBuilder(); getSelectList(current, sbr); ViewData["edit"] = sbr.ToString();//修改時，進行綁定 return View(); }ＭＶＣ頁面代碼相關：
@Html.Raw(ViewData["edit"].ToString())
Ｃ#樹型結構實體類相關：
/// <summary> /// 樹型分類結構 /// </summary> public class Category { /// <summary> /// 父ＩＤ /// </summary> public int ParentID { get; set; } /// <summary> /// 樹ＩＤ /// </summary> public int ID { get; set; } /// <summary> /// 樹名稱 /// </summary> public string Name { get; set; } /// <summary> /// 深度 /// </summary> public int Level { get; set; } /// <summary> /// 子孫節點 /// </summary> public List<Category> Sons { get; set; } /// <summary> /// 父節點 /// </summary> public Category Parent { get; set; } }好了，現在我們的Ｎ級無限下拉列表框就做好了，感謝大家的閱讀。
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