《ASP.NET MVC 4 实战》学习笔记 2：第一个MVC用程序(下)_.NET_编程开发_程序员俱乐部

上一篇VS帮我们创建了简单的操作页面，实现了CRUD功能，但是具体是怎样实现的，本篇试着分析一下。

1.视图(以Create视图为例)：

class="code_img_closed" src="/Upload/Images/2014110510/0015B68B3C38AA5B.gif" alt="" />logs_code_hide('829b731a-e566-4702-85ce-e43e507f2581',event)" src="/Upload/Images/2014110510/2B1B950FA3DF188F.gif" alt="" />

 1 @* 说明：此段话左右两端括起来的部分表示注释 *@
 2 
 3 @* 下面的@model表示利用强类型的方法来将数据或对象传递到视图模板中 *@
 4 
 5 @* @前缀表示HTML与代码之间的转换 *@
 6 
 7 @model Guestbook.Models.GuestbookEntry 
 8 
 9 @{ 
10     ViewBag.Title = "Create";
11 }
12 
13 <h2>Create</h2>
14 
15 @*Html.BeginForm 用来构建表单*@
16 
17 @using (Html.BeginForm()) 
18 {
19     @Html.AntiForgeryToken() @*@Html.AntiForgeryToken 防止跨站请求伪造*@
20     
21     <div class="form-horizontal">
22         <h4>GuestbookEntry</h4>
23         <hr />
24         @Html.ValidationSummary(true) @*@Html.ValidationSummary 显示验证消息*@
25 
26         <div class="form-group">
27             @Html.LabelFor(model => model.Name, new { @class = "control-label col-md-2" }) @*创建一个Label*@
28             <div class="col-md-10">
29                 @Html.EditorFor(model => model.Name) @* 创建一个编辑框 此编辑框输入的内容即是GuestbookEntry中Name字段对应的值 *@
30                 @Html.ValidationMessageFor(model => model.Name) @* Name字段的验证 *@
31             </div>
32         </div>
33 
34         <div class="form-group">
35             @Html.LabelFor(model => model.Message, new { @class = "control-label col-md-2" })
36             <div class="col-md-10">
37                 @Html.EditorFor(model => model.Message)
38                 @Html.ValidationMessageFor(model => model.Message)
39             </div>
40         </div>
41 
42         <div class="form-group">
43             @Html.LabelFor(model => model.DateAdded, new { @class = "control-label col-md-2" })
44             <div class="col-md-10">
45                 @Html.EditorFor(model => model.DateAdded)
46                 @Html.ValidationMessageFor(model => model.DateAdded)
47             </div>
48         </div>
49 
50         <div class="form-group">
51             <div class="col-md-offset-2 col-md-10">
52                 <input type="submit" value="Create" class="btn btn-default" />
53             </div>
54         </div>
55     </div>
56 }
57 
58 <div>
59     @Html.ActionLink("Back to List", "Index")
60 </div>
61 
62 @section Scripts {
63     @Scripts.Render("~/bundles/jqueryval")
64 }

View Code

2.控制器：

  1 namespace Guestbook.Controllers
  2 {
  3     public class GuestbookController : Controller
  4     {
  5         private GuestbookContext db = new GuestbookContext();
  6 
  7         // GET: /Guestbook/
  8         public ActionResult Index()
  9         {
 10             return View(db.Entries.ToList());
 11         }
 12 
 13         // GET: /Guestbook/Details/5
 14         public ActionResult Details(int? id)
 15         {
 16             if (id == null)
 17             {
 18                 return new HttpStatusCodeResult(HttpStatusCode.BadRequest);
 19             }
 20             GuestbookEntry guestbookentry = db.Entries.Find(id);
 21             if (guestbookentry == null)
 22             {
 23                 return HttpNotFound();
 24             }
 25             return View(guestbookentry);
 26         }
 27 
 28         // GET: /Guestbook/Create
 29         public ActionResult Create()
 30         {
 31             return View();
 32         }
 33 
 34         // POST: /Guestbook/Create
 35         // To protect from overposting attacks, please enable the specific properties you want to bind to, for 
 36         // more details see http://go.microsoft.com/fwlink/?LinkId=317598.
 37         [HttpPost]
 38         [ValidateAntiForgeryToken]
 39         public ActionResult Create([Bind(Include="Id,Name,Message,DateAdded")] GuestbookEntry guestbookentry)
 40         {
 41             if (ModelState.IsValid)
 42             {
 43                 db.Entries.Add(guestbookentry);
 44                 db.SaveChanges();
 45                 return RedirectToAction("Index");
 46             }
 47 
 48             return View(guestbookentry);
 49         }
 50 
 51         // GET: /Guestbook/Edit/5
 52         public ActionResult Edit(int? id)
 53         {
 54             if (id == null)
 55             {
 56                 return new HttpStatusCodeResult(HttpStatusCode.BadRequest);
 57             }
 58             GuestbookEntry guestbookentry = db.Entries.Find(id);
 59             if (guestbookentry == null)
 60             {
 61                 return HttpNotFound();
 62             }
 63             return View(guestbookentry);
 64         }
 65 
 66         // POST: /Guestbook/Edit/5
 67         // To protect from overposting attacks, please enable the specific properties you want to bind to, for 
 68         // more details see http://go.microsoft.com/fwlink/?LinkId=317598.
 69         [HttpPost]
 70         [ValidateAntiForgeryToken]
 71         public ActionResult Edit([Bind(Include="Id,Name,Message,DateAdded")] GuestbookEntry guestbookentry)
 72         {
 73             if (ModelState.IsValid)
 74             {
 75                 db.Entry(guestbookentry).State = EntityState.Modified;
 76                 db.SaveChanges();
 77                 return RedirectToAction("Index");
 78             }
 79             return View(guestbookentry);
 80         }
 81 
 82         // GET: /Guestbook/Delete/5
 83         public ActionResult Delete(int? id)
 84         {
 85             if (id == null)
 86             {
 87                 return new HttpStatusCodeResult(HttpStatusCode.BadRequest);
 88             }
 89             GuestbookEntry guestbookentry = db.Entries.Find(id);
 90             if (guestbookentry == null)
 91             {
 92                 return HttpNotFound();
 93             }
 94             return View(guestbookentry);
 95         }
 96 
 97         // POST: /Guestbook/Delete/5
 98         [HttpPost, ActionName("Delete")]
 99         [ValidateAntiForgeryToken]
100         public ActionResult DeleteConfirmed(int id)
101         {
102             GuestbookEntry guestbookentry = db.Entries.Find(id);
103             db.Entries.Remove(guestbookentry);
104             db.SaveChanges();
105             return RedirectToAction("Index");
106         }
107 
108         protected override void Dispose(bool disposing)
109         {
110             if (disposing)
111             {
112                 db.Dispose();
113             }
114             base.Dispose(disposing);
115         }
116     }
117 }

View Code

从上面的代码中我们可以看到Create和Edit方法均有两个重载[其实Delete方法也有两个重载，只是由于这两个方法具有类型和个数相同的参数另一个被命名为DeleteConfirmed，然后添加ActionName("Delete")注解表示负责处理Delete视图的动作]。两个同名的方法一个在加载时渲染视图，另一个处理视图的动作(用HttpPost注解属性修饰)。

3.布局：

 有没有感觉我们的CRUD页面使用了Master Page之类的东西，是的，默认布局为Views\Shared\_Layout.cshtml，代码如下：

 1 <!DOCTYPE html>
 2 <html>
 3 <head>
 4     <meta charset="utf-8" />
 5     <meta name="viewport" content="width=device-width, initial-scale=1.0">
 6     <title>@ViewBag.Title - My ASP.NET Application</title>
 7     @Styles.Render("~/Content/css")
 8     @Scripts.Render("~/bundles/modernizr")
 9 
10 </head>
11 <body>
12     <div class="navbar navbar-inverse navbar-fixed-top">
13         <div class="container">
14             <div class="navbar-header">
15                 <button type="button" class="navbar-toggle" data-toggle="collapse" data-target=".navbar-collapse">
16                     <span class="icon-bar"></span>
17                     <span class="icon-bar"></span>
18                     <span class="icon-bar"></span>
19                 </button>
20                 @Html.ActionLink("Application name", "Index", "Home", null, new { @class = "navbar-brand" })
21             </div>
22             <div class="navbar-collapse collapse">
23                 <ul class="nav navbar-nav">
24                     <li>@Html.ActionLink("Home", "Index", "Home")</li>
25                     <li>@Html.ActionLink("About", "About", "Home")</li>
26                     <li>@Html.ActionLink("Contact", "Contact", "Home")</li>
27                 </ul>
28                 @Html.Partial("_LoginPartial") @*渲染一个部分视图*@
29             </div>
30         </div>
31     </div>
32     <div class="container body-content">
33         @RenderBody() @*待渲染的页面内容*@
34         <hr />
35         <footer>
36             <p>&copy; @DateTime.Now.Year - My ASP.NET Application</p>
37         </footer>
38     </div>
39 
40     @Scripts.Render("~/bundles/jquery")
41     @Scripts.Render("~/bundles/bootstrap")
42     @RenderSection("scripts", required: false)
43 </body>
44 </html>

View Code

那么视图和默认布局是怎样关联起来的呢，答案就在Views\_ViewStart.cshtml中：

1 @{
2     Layout = "~/Views/Shared/_Layout.cshtml";
3 }

View Code

_ViewStart会在所有视图被执行之前执行，它设定了默认的布局，如果视图没有特别指定Layout的话，就会使用这个预设布局。