[转]Asp.NET MVC Widget开发 - ViewEngine

本文转自：http://www.cnblogs.com/hsinlu/archive/2011/03/02/1968796.html

在Asp.NET开发博客类系统，我们经常都会用到Widget，像在线好友、最近访问好友、最新留言等，关于Asp.NET MVC与Asp.NET视图的差异，这里不再说了，大家可去查一下，接下来我以“我的好友”列表来要介绍在Asp.NET MVC实现这一功能以及结构设计。

• 开发工具：VS 2010 EN
• 开发语言：Visual C#
• ASP.NET MVC 3

1. Asp.NET MVC Widget - 设计
2. Asp.NET MVC Widget - Controller控制器
3. Asp.NET MVC Widget - ViewEngine
4. Asp.NET MVC Widget - Mobile支持
5. Asp.NET MVC Widget - Html.Widget扩展方法

关于ViewEngine这篇是Widgets实现的核心，这里需要自定义Asp.NET MVC的视图引擎，也就是让Asp.NET MVC视图引擎可以找到widgets中的文件。

直接访问会出现以下错误，提示找不到显示文件

由错误中也可以看到 Asp.NET MVC默认引擎搜索文件的目录

/Views/Widget/

/Views/Shared/

要寻找到"widgets"中的文件就必须要让视图引擎去"widgets"中搜索文件

如Friends: /widgets/Friends/

添加自定义视图引擎

1. 添加 "WidgetViewEngine.cs"，继承自BuildManagerViewEngine

using System; using System.Collections.Generic; using System.Linq; using System.Web; using System.Web.Mvc;
namespace Widgets {     public class WidgetViewEngine : BuildManagerViewEngine     {         internal static readonly string ViewStartFileName = "_ViewStart";
        public WidgetViewEngine()             : this(null)         {         }
        public WidgetViewEngine(IViewPageActivator viewPageActivator)             : base(viewPageActivator)         {             AreaViewLocationFormats = new[] {                 "~/Areas/{2}/Views/{1}/{0}.cshtml",                 "~/Areas/{2}/Views/Shared/{0}.cshtml"             };             AreaMasterLocationFormats = new[] {                 "~/Areas/{2}/Views/{1}/{0}.cshtml",                 "~/Areas/{2}/Views/Shared/{0}.cshtml"             };             AreaPartialViewLocationFormats = new[] {                 "~/Areas/{2}/Views/{1}/{0}.cshtml",                 "~/Areas/{2}/Views/Shared/{0}.cshtml"             };
            ViewLocationFormats = new[] {                 "~/Views/{1}/{0}.cshtml",                 "~/Views/Shared/{0}.cshtml"
            };             MasterLocationFormats = new[] {                 "~/Views/{1}/{0}.cshtml",                 "~/Views/Shared/{0}.cshtml"             };             PartialViewLocationFormats = new[] {                  "~/{1}s/{0}/Widget.cshtml",                 "~/Views/{1}/{0}.cshtml",                 "~/Views/Shared/{0}.cshtml"             };
            FileExtensions = new[] {                 "cshtml"             };         }
        protected override IView CreatePartialView(ControllerContext controllerContext, string partialPath)         {             return new RazorView(controllerContext, partialPath,                                  layoutPath: null, runViewStartPages: false, viewStartFileExtensions: FileExtensions, viewPageActivator: ViewPageActivator);         }
        protected override IView CreateView(ControllerContext controllerContext, string viewPath, string masterPath)         {             var view = new RazorView(controllerContext, viewPath,                                      layoutPath: masterPath, runViewStartPages: true, viewStartFileExtensions: FileExtensions, viewPageActivator: ViewPageActivator);             return view;         }     } }

2. 添加AppStart_Widgets.cs，修改默认视图引擎

using System; using System.Collections.Generic; using System.Linq; using System.Web; using System.Web.Mvc; using Widgets;
[assembly: PreApplicationStartMethod(typeof(AppStart_Widgets), "Start")]
namespace Widgets {     public class AppStart_Widgets     {         public static void Start()         {             // Clear system default view engines             ViewEngines.Engines.Clear();             ViewEngines.Engines.Add(new WidgetViewEngine());         }     } }

3. 添加Friend实体及测试数据

using System; using System.Collections.Generic; using System.Linq; using System.Web;
namespace Widgets.Models {     public class Friend     {         public int Id { get; set; }         public string Name { get; set; }     }
    public class FriendsContext     {         public FriendsContext()         {             Friends = new List<Friend>() {                  new Friend{Id=1,Name="zhang san"},                 new Friend{Id=2,Name="li si"},                 new Friend{Id=3,Name="wang wu"}             };         }
        public IEnumerable<Friend> Friends { get; private set; }     } }

4. 更改widgets/Friends/Widget.cshtml

@model IEnumerable<Widgets.Models.Friend> @{     Layout = "~/widgets/_Layout.cshtml";     ViewBag.Title = "My friends"; } <div class="newsletter">     <ul>         @foreach (var item in Model)         {             <li>@item.Name</li>         }     </ul> </div>

项目结构

其它代码详见源码中。

再次访问，便出现要的结果。

源码下载