在需要處理很多分類以及導航的時候，樹形導航菜單就比較適合。例如在汽車之家上：
頁面主要分兩部分，左邊是導航菜單，右邊顯示對應的內容。現在，我們就在ASP.NET MVC 4 下臨摹一個，如下：
實現的效果包括：
1、點擊導航菜單上的品牌，左側顯示該品牌下的所有車型。
2、點擊導航菜單上的車系，左側顯示該車系下的所有車型。
3、點擊左側上方的字母導航，錨點跳到導航菜單的對應部分。
4、頁面加載完畢，顯示所有品牌和車系，即樹形導航完全展開。
5、點擊導航菜單上的品牌，收縮或展開對應的車系，收縮時，品牌前面圖標為+號，展開時，品牌前面的圖片為-號。
......
源碼部分，在這里。
思路呢？
頁面分成左右2部分，使用Bootstrap輕松實現：
<div class="row"><div class="col-md-2 col-lg-2 col-sm-2"></div><div class="col-md-10 col-lg-10 col-sm-10"></div></div>
左側最上方的字母導航，被放在一個div中，頁面加載的時候向控制器動態請求。
品牌上方的字母歸類，比如奧迪上方的字母A，實際上是一個div。
品牌和車系放在了ul中，比如奧迪品牌以及奧迪下的奧迪A4和奧迪A6車系。車系被放在了dl中。
樹形菜單采用模版比較合適，先把數據填充到模版，再把模版追加到頁面元素。
當點擊左側樹形導航上的品牌或車系，右側通過iframe來呈現對應的內容。
領域先行。有關品牌和車系就抽象成如下的類：
public class CarCategory{public int Id { get; set; }public int ParentId { get; set; }public string Name { get; set; }public string FirstLetter { get; set; }public string AnchorName { get; set; }public int Level { get; set; }public short DelFlag { get; set; }}
有關車型就抽象成如下的類：
public class Car{public int Id { get; set; }public int PinPaiId { get; set; }public int CheXiId { get; set; }public string Name { get; set; }}
頁面左側呈現樹形導航需要向控制器請求json數據，大致格式是：
首字母
錨點名稱
所有品牌
品牌編號
品牌名稱
所有車系
車系編號
車系名稱
車系下車型的總數量
貌似有3層，那就從最里面這層開始建模。有關車系在樹形導航中的顯示：
public class CheXiForDisplay{public int CheXiId { get; set; }public int TotalCount { get; set; }public string CheXiName { get; set; }}
有關品牌在樹形導航中的顯示：
public class PinPaiForDisplay{public int PinPaiId { get; set; }public string PinPaiName { get; set; }public List<CheXiForDisplay> CheXis { get; set; }}
有關品牌車系分組的：
public class PinPaiCheXiForDisplay{public string FirstLetter { get; set; }public string Anchor { get; set; }public List<PinPaiForDisplay> PinPais { get; set; }}
數據源從哪里來？模擬了一個：
public class Database{public static IEnumerable<CarCategory> GetAllCarCategories(){return new List<CarCategory>{new CarCategory(){Id = 1, ParentId = 0, Name = "奧迪",FirstLetter = "A", AnchorName = "AA", Level = 1, DelFlag = 0},new CarCategory(){Id = 2, ParentId = 0, Name = "寶馬",FirstLetter = "B", AnchorName = "BB", Level = 1, DelFlag = 0},new CarCategory(){Id = 3, ParentId = 0, Name = "保時捷",FirstLetter = "B", AnchorName = "BB", Level = 1, DelFlag = 0},new CarCategory(){Id = 4, ParentId = 0, Name = "長安",FirstLetter = "C", AnchorName = "CC", Level = 1, DelFlag = 0},new CarCategory(){Id = 5, ParentId = 0, Name = "大眾",FirstLetter = "D", AnchorName = "DD", Level = 1, DelFlag = 0},new CarCategory(){Id = 6, ParentId = 0, Name = "東風",FirstLetter = "D", AnchorName = "DD", Level = 1, DelFlag = 0},new CarCategory(){Id = 7, ParentId = 0, Name = "豐田",FirstLetter = "F", AnchorName = "FF", Level = 1, DelFlag = 0},new CarCategory(){Id = 8, ParentId = 0, Name = "福特",FirstLetter = "F", AnchorName = "FF", Level = 1, DelFlag = 0},new CarCategory(){Id = 9, ParentId = 1, Name = "奧迪A4",FirstLetter = "A", AnchorName = "AA", Level = 2, DelFlag = 0},new CarCategory(){Id = 10, ParentId = 1, Name = "奧迪A6",FirstLetter = "A", AnchorName = "AA", Level = 2, DelFlag = 0},new CarCategory(){Id = 11, ParentId = 2, Name = "寶馬1",FirstLetter = "B", AnchorName = "BB", Level = 2, DelFlag = 0},new CarCategory(){Id = 12, ParentId = 2, Name = "寶馬2",FirstLetter = "B", AnchorName = "BB", Level = 2, DelFlag = 0},new CarCategory(){Id = 13, ParentId = 3, Name = "保時捷1",FirstLetter = "B", AnchorName = "BB", Level = 2, DelFlag = 0},new CarCategory(){Id = 14, ParentId = 3, Name = "保時捷2",FirstLetter = "B", AnchorName = "BB", Level = 2, DelFlag = 0},new CarCategory(){Id = 15, ParentId = 4, Name = "長安1",FirstLetter = "C", AnchorName = "CC", Level = 2, DelFlag = 0},new CarCategory(){Id = 16, ParentId = 4, Name = "長安2",FirstLetter = "C", AnchorName = "CC", Level = 2, DelFlag = 0},new CarCategory(){Id = 17, ParentId = 5, Name = "大眾1",FirstLetter = "D", AnchorName = "DD", Level = 2, DelFlag = 0},new CarCategory(){Id = 18, ParentId = 5, Name = "大眾2",FirstLetter = "D", AnchorName = "DD", Level = 2, DelFlag = 1},new CarCategory(){Id = 19, ParentId = 6, Name = "東風1",FirstLetter = "D", AnchorName = "DD", Level = 2, DelFlag = 0},new CarCategory(){Id = 20, ParentId = 6, Name = "東風2",FirstLetter = "D", AnchorName = "DD", Level = 2, DelFlag = 0},new CarCategory(){Id = 21, ParentId = 7, Name = "豐田1",FirstLetter = "F", AnchorName = "FF", Level = 2, DelFlag = 0},new CarCategory(){Id = 22, ParentId = 7, Name = "豐田2",FirstLetter = "F", AnchorName = "FF", Level = 2, DelFlag = 0},new CarCategory(){Id = 23, ParentId = 8, Name = "福特1",FirstLetter = "F", AnchorName = "AFF", Level = 2, DelFlag = 0},new CarCategory(){Id = 24, ParentId = 8, Name = "福特2",FirstLetter = "F", AnchorName = "AFF", Level = 2, DelFlag = 0}};}public static IEnumerable<Car> GetAllCars(){return new List<Car>{new Car(){Id = 1, PinPaiId = 1, CheXiId = 9, Name = "奧迪A401"},new Car(){Id = 2, PinPaiId = 1, CheXiId = 9, Name = "奧迪A402"},new Car(){Id = 3, PinPaiId = 1, CheXiId = 10, Name = "奧迪A601"},new Car(){Id = 4, PinPaiId = 1, CheXiId = 10, Name = "奧迪A602"},new Car(){Id = 5, PinPaiId = 2, CheXiId = 11, Name = "寶馬101"},new Car(){Id = 6, PinPaiId = 2, CheXiId = 11, Name = "寶馬102"},new Car(){Id = 7, PinPaiId = 2, CheXiId = 12, Name = "寶馬201"},new Car(){Id = 8, PinPaiId = 2, CheXiId = 12, Name = "寶馬202"},new Car(){Id = 9, PinPaiId = 3, CheXiId = 13, Name = "保時捷101"},new Car(){Id = 10, PinPaiId = 3, CheXiId = 13, Name = "保時捷102"},new Car(){Id = 11, PinPaiId = 3, CheXiId = 14, Name = "保時捷201"},new Car(){Id = 12, PinPaiId = 3, CheXiId = 14, Name = "保時捷202"},new Car(){Id = 13, PinPaiId = 4, CheXiId = 15, Name = "長安101"},new Car(){Id = 14, PinPaiId = 4, CheXiId = 15, Name = "長安102"},new Car(){Id = 15, PinPaiId = 4, CheXiId = 16, Name = "長安201"},new Car(){Id = 16, PinPaiId = 4, CheXiId = 16, Name = "長安202"},new Car(){Id = 17, PinPaiId = 5, CheXiId = 17, Name = "大眾101"},new Car(){Id = 18, PinPaiId = 5, CheXiId = 17, Name = "大眾102"},new Car(){Id = 19, PinPaiId = 5, CheXiId = 18, Name = "大眾201"},new Car(){Id = 20, PinPaiId = 5, CheXiId = 18, Name = "大眾202"},new Car(){Id = 21, PinPaiId = 6, CheXiId = 19, Name = "東風101"},new Car(){Id = 22, PinPaiId = 6, CheXiId = 19, Name = "東風102"},new Car(){Id = 23, PinPaiId = 6, CheXiId = 20, Name = "東風201"},new Car(){Id = 24, PinPaiId = 6, CheXiId = 20, Name = "東風202"},new Car(){Id = 25, PinPaiId = 7, CheXiId = 21, Name = "豐田101"},new Car(){Id = 26, PinPaiId = 7, CheXiId = 21, Name = "豐田102"},new Car(){Id = 27, PinPaiId = 7, CheXiId = 22, Name = "豐田201"},new Car(){Id = 28, PinPaiId = 7, CheXiId = 22, Name = "豐田202"},new Car(){Id = 29, PinPaiId = 8, CheXiId = 23, Name = "福特101"},new Car(){Id = 30, PinPaiId = 8, CheXiId = 23, Name = "福特102"},new Car(){Id = 31, PinPaiId = 8, CheXiId = 24, Name = "福特201"},new Car(){Id = 32, PinPaiId = 8, CheXiId = 24, Name = "福特202"}};}}
好，現在可以向控制器要數據了。
public class HomeController : Controller{public ActionResult Index(){return View();}//獲取所有首字母以及錨點的jsonpublic ActionResult GetFirstLettersJson(){var allCarCategories = Database.GetAllCarCategories();var result = from l in allCarCategoriesgroup l by l.FirstLetterinto gselect new {firstletter = g.Key, anchor=g.ToList()[0].AnchorName};return Json(result, JsonRequestBehavior.AllowGet);}//獲取按首字母分組后的品牌車系jsonpublic ActionResult GetPinPaiCheXiJson(){var allPinPais = Database.GetAllCarCategories().Where(c => c.Level == 1).OrderBy(c => c.FirstLetter);var allPinPaisGroup = from p in allPinPaisgroup p by new{p.FirstLetter,p.AnchorName};List<PinPaiCheXiForDisplay> result1 = new List<PinPaiCheXiForDisplay>();foreach (var item in allPinPaisGroup){//品牌車系PinPaiCheXiForDisplay pinPaiCheXiForDisplay = new PinPaiCheXiForDisplay();pinPaiCheXiForDisplay.FirstLetter = item.Key.FirstLetter;pinPaiCheXiForDisplay.Anchor = item.Key.AnchorName;//品牌List<PinPaiForDisplay> pinPaiForDisplays = new List<PinPaiForDisplay>();foreach (var pinpai in item.ToList()){PinPaiForDisplay pinPaiForDisplay = new PinPaiForDisplay();pinPaiForDisplay.PinPaiId = pinpai.Id;pinPaiForDisplay.PinPaiName = pinpai.Name;//車系List<CheXiForDisplay> cheXiForDisplays = new List<CheXiForDisplay>();var cheXis = Database.GetAllCarCategories().Where(c => c.ParentId == pinpai.Id).OrderBy(c => c.Id);foreach (var chexi in cheXis){CheXiForDisplay cheXiForDisplay = new CheXiForDisplay();cheXiForDisplay.CheXiId = chexi.Id;cheXiForDisplay.CheXiName = chexi.Name;cheXiForDisplay.TotalCount = cheXis.Count();cheXiForDisplays.Add(cheXiForDisplay);}pinPaiForDisplay.CheXis = cheXiForDisplays;pinPaiForDisplays.Add(pinPaiForDisplay);}pinPaiCheXiForDisplay.PinPais = pinPaiForDisplays;result1.Add(pinPaiCheXiForDisplay);}return Json(result1, JsonRequestBehavior.AllowGet);}//根據品牌Id顯示車型public ActionResult GetCheXingsByPId(int pid){var cars = Database.GetAllCars().Where(c => c.PinPaiId == pid);return View(cars);}//根據車系Id顯示車型public ActionResult GetCheXingsByChexiId(int cxid){var cars = Database.GetAllCars().Where(c => c.CheXiId == cxid);return View(cars);}}
在Shared/_Layout.cshtml中，該引用的css,js都要引用上。
<head><meta charset="utf-8" /><meta name="viewport" content="width=device-width" /><title>@ViewBag.Title</title><link href="~/bootstrap/css/bootstrap.min.css" rel="stylesheet" />@Styles.Render("~/Content/css")@RenderSection("styles", required: false)@Scripts.Render("~/bundles/jquery")<script src="~/bootstrap/js/bootstrap.min.js"></script></head><body>@RenderBody()@RenderSection("scripts", required: false)</body>
Home/Index.cshtml就負責顯示就行了。
@{ViewBag.Title = "Index";Layout = "~/Views/Shared/_Layout.cshtml";}@section styles{<link href="~/Content/sidemenu.css" rel="stylesheet" />}<div class="row"><div class="col-md-2 col-lg-2 col-sm-2"><!--字母導航開始--><div id="lDaoHang"></div><!--字母導航結束--><!--樹開始--><div id="cTreeDiv" style="overflow-x: hidden; overflow-y: scroll; height: 550px; width: 99%;"></div><!--樹結束--><div><dl id="test"></dl></div></div><div class="col-md-10 col-lg-10 col-sm-10"><div class="carContent" id="carContent"><iframe id="frameCar" src="" scrolling="no" frameborder="0" height="100%" width="100%" onload="this.height=this.contentWindow.document.documentElement.scrollHeight"></iframe></div></div></div>@section scripts{<script src="~/Scripts/jquery.tmpl.min.js"></script><script type="text/javascript">$(function () {//加載首字母$.getJSON('@Url.Action("GetFirstLettersJson", "Home")', function (data) {$('#firstLetterTemplate').tmpl(data).appendTo('#lDaoHang');});//加載所有品牌車系$.getJSON('@Url.Action("GetPinPaiCheXiJson", "Home")', function (data) {$('#pinpaiTemplate').tmpl(data).appendTo('#cTreeDiv');$('.pLink').each(function () {pinPaiInitialState($(this));});});//隱藏ifame所在div$("#carContent").css("display", "none");//點擊品牌$('#cTreeDiv').on("click", ".pLink", function () {//切換togglePinPaiState($(this));//顯示右邊區域var url = "/Home/GetCheXingsByPId?pid=" + $(this).attr('id');$("#frameCar").attr("src", url);$("#carContent").css("display", "block");});//點擊車系$('#cTreeDiv').on("click", ".cxLink", function () {//顯示右邊區域var url = "/Home/GetCheXingsByChexiId?cxid=" + $(this).attr('id');$("#frameCar").attr("src", url);$("#carContent").css("display", "block");});});//品牌的初始狀態,即把車系隱藏和品牌前面的圖標為+號var pstate = 0;//品牌只有2種狀態：所有車系隱藏，品牌前面的圖標變為為+號；要么顯示品牌下的所有車系，品牌前面的圖標變為-號//把車系隱藏和品牌前面的圖標為+號，記為狀態0//把車系隱藏和品牌前面的圖標為-號，記為狀態1function togglePinPaiState($pinpai) {if (pstate == 0) {var $i = $pinpai.parent().find("i");var attr = $i.attr('class');if (typeof attr !== typeof undefined && attr !== false) {$i.removeClass("iconHide");}$i.addClass("iconShow");$pinpai.parent().parent().find("dl").show();pstate = 1;} else {var $j = $pinpai.parent().find("i");var attr1 = $j.attr('class');if (typeof attr1 !== typeof undefined && attr1 !== false) {$j.removeClass("iconShow");}$j.addClass("iconHide");$pinpai.parent().parent().find("dl").hide();pstate = 0;}}function pinPaiInitialState($pinpai) {pstate = 0;togglePinPaiState($pinpai);}</script><!--首字母模版--><script id="firstLetterTemplate" type="text/x-jQuery-tmpl"><div class="lWrapper"><a href="#${anchor}" class="lLink">${firstletter}</a></div></script><!--品牌模版--><script id="pinpaiTemplate" type="text/x-jQuery-tmpl"><div class="lHeader" id="${Anchor}">${FirstLetter}</div><ul class="uTree">{{if PinPais}}{{each PinPais}}<li><h5 class="font-bold"><a href="javascript:void(0)" class="pLink" id="${$value.PinPaiId}"><i></i>${$value.PinPaiName}</a></h5><dl>{{tmpl(CheXis) "#chexiTemplate"}}</dl></li>{{/each}}{{else}}<li>沒有對應品牌</li>{{/if}}</ul></script><!--車系模版--><script id="chexiTemplate" type="text/x-jQuery-tmpl"><dd><a id="${CheXiId}" href="javascript:void(0)" class="cxLink">${CheXiName}<em>(${TotalCount})</em></a></dd></script>}
以上，
○ 從控制器返回的有關樹形菜單的json數據，先填充到jquery.tmpl.min.js模版中，然后追加到頁面上。
○ 樹形菜單的展開或收縮，通過全局變量pstate在0和1之間的切換來實現，頁面初次加載給變量pstate一個初始值。
另外，點擊樹形導航上的品牌，iframe加載的視圖是Home/GetCheXingsByPId.cshtml
@model IEnumerable<MvcApplication1.Models.Car>@{ViewBag.Title = "GetCheXingsByPId";Layout = "~/Views/Shared/_Layout.cshtml";}<h2>GetCheXingsByPId</h2><div>@foreach (var item in Model){<p>@item.Name </p>}</div>
點擊樹形導航上的車系，iframe加載的視圖是Home/GetCheXingsByChexiId.cshtml
@model IEnumerable<MvcApplication1.Models.Car>@{ViewBag.Title = "GetCheXingsByChexiId";Layout = "~/Views/Shared/_Layout.cshtml";}<h2>GetCheXingsByChexiId</h2><div>@foreach (var item in Model){<p>@item.Name </p>}</div
就這樣。