在ASP.NET MVC中实现一种不同于平常的三级联动、级联方式, 可用于城市、车型选择等多层级联场景
三级或多级联动的场景经常会碰到，比如省、市、区，比如品牌、车系、车型，比如类别的多级联动......我们首先想到的是用三个select来展示，这是最通常的做法。但在另外一些场景中，比如确定搜索条件的时候，对于三级联动来说，可能选择1个，2个，或3个条件，我想，以下的方式可能更适合：
以上，可以只选择品牌，或同时选择品牌、车系，或同时选择品牌、车系、车型，最后把选择的内容展示到input上，并以逗号隔开。
可以实现的功能包括：
○ 点击最上面的input弹出div，此时只显示品牌区域
○ 点击最左边拼音首字母，导航到对应的品牌上
○ 当把鼠标移动到某个品牌上，品牌为选中状态，其对应的车系显示在车系区域
○ 当鼠标不在任何品牌上，所有品牌都为不选中状态
○ 当把鼠标移动到某个车系上，车系为选中状态，其对应的车型显示在车型区域，选中车系的所属品牌也为选中状态
○ 当鼠标不在任何车系上，所有车系、品牌都为不选中状态
○ 当把鼠标移动到某个车型上，车型为选中状态，选中车型的所属车系为选中状态，选中车系所属品牌为选中状态
○ 当鼠标不在任何车型上，所有车型、车系、品牌为不选中状态
○ 点击品牌，品牌显示到input上
○ 点击车系，品牌、车系显示到input上，并以逗号隔开
○ 点击车型，品牌、车系、车型显示到input上，并以逗号隔开
○ 点击div上的关闭按钮或者页面空白区域，div隐藏
界面的构成如下：
○ 最上面的是一个input
○ 品牌、车系、车型被包裹在一个div中，点击关闭按钮或点击空白处关闭的就是这个div
○ 品牌区域是一个div，分为首字母导航div和品牌显示div
○ 车系区域是一个div
○ 车型区域是一个div
○ 品牌、车系、车型内的内容是一些dl, dt, dd的html元素
○ 样式的事情交给css
实现的思路大致这样：
○ 给input点击事件，点击弹出品牌、车系、车型显示的div，并绑定页面空白区域的点击事件
○ 导航首字母指向锚点，品牌按首字母分类并提供锚点id
○ 在控制器中把品牌按照首字母分类，以json格式返回到前端，填充到tmpl模版，再追加到页面品牌区域
○ 给品牌添加鼠标移上事件，品牌为选中状态，对应的车系显示在车系区域
○ 给品牌添加鼠标移去事件
○ 给品牌添加点击事件，把点击品牌显示到input上
○ 给车系添加鼠标移上事件，当前车系为选中状态，其对应的车型显示在车型区域，其所属的品牌为选中状态
○ 给车系添加鼠标移去事件
○ 给车系添加点击事件，把点击车系和所属品牌显示到input上，以逗号隔开
○ 给车型添加鼠标移上事件，当前车型为选择状态，其所属父类车系为选中状态，车型所属父类品牌也为选中状态
○ 给车型添加点击事件，把点击车型和所属车系、品牌显示到input上，以逗号隔开
○ 给关闭按钮添加点击事件，关闭div，并解除页面空白区域点击事件的绑定
领域先行，首先是有关品牌、车系、车型的模型：
public class CarCategory{public int Id { get; set; }public string Name { get; set; }public int PId { get; set; }public string FirstLetter { get; set; }public string AnchorName { get; set; }public int Level { get; set; }}
○ PId属性用来表示父类Id,车系的父类Id为某个品牌Id,车型的父类Id为某个车系Id
○ FirstLetter属性用来表示首字母，作为分组的条件
○ AnchorName属性用来表示品牌的锚点id，车系和车型此项为空
在ASP.NET MVC4中，在Shared/Layout.cshtml中，该有的css,js都必须有：
<head><meta charset="utf-8" /><meta name="viewport" content="width=device-width" /><title>@ViewBag.Title</title>@Styles.Render("~/Content/css")@RenderSection("styles", required: false)<link href="~/bootstrap/css/bootstrap.min.css" rel="stylesheet" />@Scripts.Render("~/bundles/jquery")<script src="~/bootstrap/js/bootstrap.min.js"></script></head><body>@RenderBody()@RenderSection("scripts", required: false)</body>
模拟一个数据库，该数据库类可以获取到所有的品牌、车系、车型，以及根据品牌Id或车系Id获取对应的车系和车型。
public class Database{public static IEnumerable<CarCategory> GetCarCategories(){return new List<CarCategory>(){new CarCategory(){Id = 0, Name = "奥迪",FirstLetter = "A",AnchorName = "aa", Level = 1, PId = -1},new CarCategory(){Id = 1, Name = "奥斯顿·马丁",FirstLetter = "A",AnchorName = "aa", Level = 1, PId = -1},new CarCategory(){Id = 2, Name = "宝骏",FirstLetter = "B",AnchorName = "bb", Level = 1, PId = -1},new CarCategory(){Id = 3, Name = "巴博斯",FirstLetter = "B",AnchorName = "bb", Level = 1, PId = -1},new CarCategory(){Id = 4, Name = "北汽威旺",FirstLetter = "B",AnchorName = "bb", Level = 1, PId = -1},new CarCategory(){Id = 5, Name = "北汽制造",FirstLetter = "B",AnchorName = "bb", Level = 1, PId = -1},new CarCategory(){Id = 6, Name = "奔驰",FirstLetter = "B",AnchorName = "bb", Level = 1, PId = -1},new CarCategory(){Id = 7, Name = "别克",FirstLetter = "B",AnchorName = "bb", Level = 1, PId = -1},new CarCategory(){Id = 8, Name = "宾利",FirstLetter = "B",AnchorName = "bb", Level = 1, PId = -1},new CarCategory(){Id = 9, Name = "保时捷",FirstLetter = "B",AnchorName = "bb", Level = 1, PId = -1},new CarCategory(){Id = 10, Name = "比亚迪",FirstLetter = "B",AnchorName = "bb", Level = 1, PId = -1},new CarCategory(){Id = 11, Name = "奔腾",FirstLetter = "B",AnchorName = "bb", Level = 1, PId = -1},new CarCategory(){Id = 12, Name = "标致",FirstLetter = "B",AnchorName = "bb", Level = 1, PId = -1},new CarCategory(){Id = 13, Name = "本田",FirstLetter = "B",AnchorName = "bb", Level = 1, PId = -1},new CarCategory(){Id = 14, Name = "宝马",FirstLetter = "B",AnchorName = "bb", Level = 1, PId = -1},new CarCategory(){Id = 15, Name = "北京汽车",FirstLetter = "B",AnchorName = "bb", Level = 1, PId = -1},new CarCategory(){Id = 16, Name = "昌河",FirstLetter = "C",AnchorName = "cc", Level = 1, PId = -1},new CarCategory(){Id = 17, Name = "长安",FirstLetter = "C",AnchorName = "cc", Level = 1, PId = -1},new CarCategory(){Id = 18, Name = "长城",FirstLetter = "C",AnchorName = "cc", Level = 1, PId = -1},new CarCategory(){Id = 19, Name = "奥迪A4",FirstLetter = "A",AnchorName = "", Level = 2, PId = 0},new CarCategory(){Id = 20, Name = "奥迪A6L",FirstLetter = "A",AnchorName = "", Level = 2, PId = 0},new CarCategory(){Id = 21, Name = "奥迪Q3",FirstLetter = "A",AnchorName = "", Level = 2, PId = 0},new CarCategory(){Id = 22, Name = "奥迪A4舒适版",FirstLetter = "A",AnchorName = "", Level = 3, PId = 19},new CarCategory(){Id = 23, Name = "奥迪A4尊贵版",FirstLetter = "A",AnchorName = "", Level = 3, PId = 19},new CarCategory(){Id = 24, Name = "奥迪A6L舒适版",FirstLetter = "A",AnchorName = "", Level = 3, PId = 20},new CarCategory(){Id = 25, Name = "奥迪A6L黄金版",FirstLetter = "A",AnchorName = "", Level = 3, PId = 20},new CarCategory(){Id = 26, Name = "奥迪Q3舒适版",FirstLetter = "A",AnchorName = "", Level = 3, PId = 21},new CarCategory(){Id = 27, Name = "奥迪Q3至尊版",FirstLetter = "A",AnchorName = "", Level = 3, PId = 21},};}//根据品牌或车系I获取所有车系或车型public static IEnumerable<CarCategory> GetCarCategoriesByPId(int pid){return GetCarCategories().Where(c => c.PId == pid);}}
在HomeController中，在前端页面加载的时候，这里提供一个分组好的所有品牌的json格式给前端；当前端把鼠标移动到某个品牌上，这里根据品牌Id返回车系的json格式给前端；当前端把鼠标移动到某个车系上，这里根据车系Id返回车型的json格式给前端。
public class HomeController : Controller{public ActionResult Index(){return View();}//获取所有品牌public ActionResult GetPinPai(){var allPinPai = Database.GetCarCategories().Where(c => c.Level == 1).OrderBy(c => c.Id);var result = from p in allPinPaigroup p by new{p.FirstLetter,p.AnchorName}into gselect new {firstletter = g.Key.FirstLetter, anchor = g.Key.AnchorName, pinpais = g};return Json(result, JsonRequestBehavior.AllowGet);}//根据品牌Id获取车系[HttpPost]public ActionResult GetCheXiByPId(int pid){var allCheXi = Database.GetCarCategoriesByPId(pid).OrderBy(c => c.Id);var result = from c in allCheXiselect new {chexi = c.Name, cxid = c.Id, parentId = c.PId};return Json(result);}//根据车系Id获取车型[HttpPost]public ActionResult GetCheXingByCxId(int cxid){var allCheXing = Database.GetCarCategoriesByPId(cxid).OrderBy(c => c.Id);var result = from c in allCheXingselect new { chexing = c.Name, chexingid = c.Id, parentId = c.PId };return Json(result);}}
在Home/Index.cshtml视图中，品牌、车系、车型内容都是先填充到tmpl模版中，然后追加到页面某个区域上的。
@{ViewBag.Title = "Index";Layout = "~/Views/Shared/_Layout.cshtml";}@section styles{<link href="~/Content/CarSelect.css" rel="stylesheet" />}<div class="input-group"><input type="text" id="mychoice" class="form-control"><span class="input-group-btn"><button class="btn btn-default" type="button">∨</button></span></div><div id="carcategory-picker-outer"><a href="javascript:void(0)" class="cancel"></a><div id="carcategory-picker-inner"><div id="pinpai" class="carcategory-list"><h6>请选择品牌</h6><div id="PreLetter"><a href="#aa">A</a><a href="#bb">B</a><a href="#cc">C</a><a href="#dd">D</a><a href="#ff">F</a><a href="#gg">G</a><a href="#hh">H</a><a href="#jj">J</a><a href="#kk">K</a><a href="#ll">L</a><a href="#mm">M</a><a href="#nn">N</a><a href="#oo">O</a><a href="#qq">Q</a><a href="#rr">R</a><a href="#ss">S</a><a href="#ww">W</a><a href="#xx">X</a><a href="#yy">Y</a><a href="#zz">Z</a></div><div id="AllPinPai"></div></div><div id="chexi" class="carcategory-list"><h6>请选择车系</h6><div id="AllCheXi"></div></div><div id="chexin" class="carcategory-list"><h6>请选择车型</h6><div id="AllCheXing"></div></div></div></div>@section scripts{<script src="~/Scripts/jquery.tmpl.min.js"></script><script type="text/javascript">$(function() {//加载所有品牌$.getJSON('@Url.Action("GetPinPai", "Home")', function(data) {$('#pinpaiTemplate').tmpl(data).appendTo('#AllPinPai');});//点击input弹出品牌车系车型选择$('#mychoice').on("click", function() {$('#carcategory-picker-outer').css('display', 'block');$("body").bind("mousedown", onBodyDown);//绑定鼠标单击事件});//点击关闭按钮隐藏品牌车系车型选择$('.cancel').on("click", function() {hideMenu();});//给所有品牌加上鼠标移动上事件$('#AllPinPai').on("mouseover", ".ppm", function() {$(this).addClass('selected');$('#chexi').css("display", "block");$.post('@Url.Action("GetCheXiByPId","Home")', { 'pid': $(this).attr('pid') }, function (data) {$('#AllCheXi').empty();$('#AllCheXing').empty();$('#chexiTemplate').tmpl(data).appendTo('#AllCheXi');});});//给所有品牌加上鼠标移去事件$('#AllPinPai').on("mouseout", ".ppm", function () {$(this).removeClass('selected');});//品牌点击事件$('#AllPinPai').on("click", ".ppm", function () {$('#mychoice').val('');$('#mychoice').val($(this).text());hideMenu();});//给车系加上鼠标移动上事件$('#AllCheXi').on("mouseover", ".cxm", function () {//取取当前车系的父类Idvar parentId = $(this).attr('parentid');//把品牌中该父类添加selected这个类$('#AllPinPai').find("a[pid='" + parentId + "']").addClass('selected');$(this).addClass('selected');$('#chexin').css("display", "block");$.post('@Url.Action("GetCheXingByCxId","Home")', { 'cxid': $(this).attr('pid') }, function (data) {$('#AllCheXing').empty();$('#chexingTemplate').tmpl(data).appendTo('#AllCheXing');});});//给车系加上鼠标移去事件$('#AllCheXi').on("mouseout", ".cxm", function () {$(this).removeClass('selected');//取取当前车系的父类Idvar parentId = $(this).attr('parentid');//把品牌中该父类添加selected这个类$('#AllPinPai').find("a[pid='" + parentId + "']").removeClass('selected');});//车系点击事件$('#AllCheXi').on("click", ".cxm", function () {$('#mychoice').val('');//取取当前车系的父类Idvar parentId = $(this).attr('parentid');$('#mychoice').val($('#AllPinPai').find("a[pid='" + parentId + "']").text() + "," + $(this).text());hideMenu();});//给车型加上鼠标移上事件$('#AllCheXing').on("mouseover", ".cxim", function () {//取出车型的父类idvar parentId = $(this).attr('parentid');//把车系中该父类添加selected这个类$('#AllCheXi').find("a[pid='" + parentId + "']").addClass('selected');//取出车系的父类idvar parentparentId = $('#AllCheXi').find("a[pid='" + parentId + "']").attr('parentid');//把品牌中该父类添加selected这个类$('#AllPinPai').find("a[pid='" + parentparentId + "']").addClass('selected');});//给车型加上鼠标移去事件$('#AllCheXing').on("mouseout", ".cxim", function () {//取出车型的父类idvar parentId = $(this).attr('parentid');//把车系中该父类添加selected这个类$('#AllCheXi').find("a[pid='" + parentId + "']").removeClass('selected');//取出车系的父类idvar parentparentId = $('#AllCheXi').find("a[pid='" + parentId + "']").attr('parentid');//把品牌中该父类添加selected这个类$('#AllPinPai').find("a[pid='" + parentparentId + "']").removeClass('selected');});//车型点击事件$('#AllCheXing').on("click", ".cxim", function () {$('#mychoice').val('');//取出车型的父类idvar parentId = $(this).attr('parentid');//取出车系的父类idvar parentparentId = $('#AllCheXi').find("a[pid='" + parentId + "']").attr('parentid');$('#mychoice').val($('#AllPinPai').find("a[pid='" + parentparentId + "']").text() + "," + $('#AllCheXi').find("a[pid='" + parentId + "']").text() + "," + $(this).text());hideMenu();});});//隐藏树并解除绑定function hideMenu() {$("#carcategory-picker-outer").fadeOut("fast");$("body").unbind("mousedown", onBodyDown);}//鼠标单击空白处事件function onBodyDown(event) {if (!(event.target.id == "mychoice" || event.target.id == "carcategory-picker-outer" || $(event.target).parents("#carcategory-picker-outer").length > 0)) {hideMenu();}}</script><script id="pinpaiTemplate" type="text/x-jQuery-tmpl"><dl><dt id="${anchor}">${firstletter}</dt>{{if pinpais}}{{each pinpais}}<dd><a class="ppm" pid="${$value.Id}">${$value.Name}</a></dd>{{/each}}{{else}}<dd>没有此品牌</dd>{{/if}}</dl></script><script id="chexiTemplate" type="text/x-jQuery-tmpl"><dl><dd><a class="cxm" pid="${cxid}" parentid="${parentId}">${chexi}</a></dd></dl></script><script id="chexingTemplate" type="text/x-jQuery-tmpl"><dl><dd><a class="cxim" pid="${chexingid}" parentid="${parentId}">${chexing}</a></dd></dl></script>}
css部分如下，关闭按钮可自找。
展开
