（19）URL—其实我更想懂你：路由用户到特定的Controller和Action

问题

当今如此对搜索引擎霸主的争夺战是如此激烈，像下边这样的网站地址很难在这场比赛中获胜：http://www.example.com/books/details?id=4

使用路由，网站可以变成这样：

http://www.example.com/20-recipes-for-mvc3

无论是对用户还是搜索引擎，这将提供更多的语境。

解决方案

使用RouteCollectionExtensions 类下的MapRoute 函数去生成更友好的名字去展示内容而不是数字ID。

讨论

在MVC中可以通过Web.config和Global.asax.cs文件设置路由。在web.config中包含 System.Web.Routing程序集并且在Global.asax.cs中使用它去对在它其中的所有controller和action创建一个默认的路由机制。因此在添加BooksController的时候，可以通过/Books 访问不带扩展名的 URL，就像在ASP.NET 官网那样。

接下来的秘方将演示设立几个不同的有用的技术去创建路由。

第一个路由将允许网站直接连接到book的title上。例如，有一本书叫MVC3的20个秘方，它可以通过http://localhost /20 Recipes for Programming MVC 3这个地址被直接访问。然而当前的解决方案就需要一个更复杂的URL就像：http://localhost/Books/Details?id=1。要开始创建这个路由，打开在MVC project里的Global.asax.cs文件。在RegisterRoutes()函数里创建里了一个默认的路由。在第一次加载网站的时候 Application_Start()函数会调用它。下边的例子包含一个更新的RegisterRoutes 函数，添加了一个新的路由到MapRoute函数中：

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using System; using System.Collections.Generic; using System.Linq; using System.Web; using System.Web.Mvc; using System.Web.Routing; using MvcApplication.Models; using System.Data.Entity; using System.Globalization; using System.Threading; namespace MvcApplication {     public class MvcApplication : System.Web.HttpApplication     {         public static void RegisterGlobalFilters(         GlobalFilterCollection filters)         {             filters.Add(new HandleErrorAttribute());         }         public static void RegisterRoutes(RouteCollection routes)         {             routes.IgnoreRoute("{resource}.axd/{*pathInfo}");             routes.MapRoute(             "BookName", // Route name             "{Keyword}", // URL with parameters             new             {                 controller = "Books",                 action = "Index",                 id = UrlParameter.Optional             },             new { Keyword = "w+" });             routes.MapRoute(             "Default", // Route name             "{controller}/{action}/{id}",                 // URL with parameters             new             {                 controller = "Home",                 action = "Index",                 id = UrlParameter.Optional             }             );         }         protected void Application_Start()         {             Database.SetInitializer<BookDBContext>(             new BookInitializer());             AreaRegistration.RegisterAllAreas();             RegisterGlobalFilters(GlobalFilters.Filters);             RegisterRoutes(RouteTable.Routes);         }         protected void Application_AcquireRequestState(         object sender, EventArgs e)         {             if (HttpContext.Current.Session != null)             {                 CultureInfo ci =                 (CultureInfo)this.Session["CurrentLanguage"];                 if (ci == null)                 {                     ci = new CultureInfo("en");                     this.Session["CurrentLanguage"] = ci;                 }                 Thread.CurrentThread.CurrentUICulture = ci;                 Thread.CurrentThread.CurrentCulture =                 CultureInfo.CreateSpecificCulture(ci.Name);             }         }     } }

 

在上边的例子里，MapRoute 函数接收4个参数。

1. route name，在这里是BookName。
2. 附带任何参数的URL。在这里是{Keyword}，这是可变的，一会儿会用到。
3. 这个参数默认的是controller ，action和任何附加的变量。在这个例子里，默认的controller是Books 并且Action是Index
4. 他包含（例如，变量）对于URL。在这里，前边提到的Keyword变量传递到BooksController的Index action上。

当搜索关键字时，他可以在URL的域名后边输入一个书名或关键字，如果仅仅返回了一个结果，用户将被重定向到详细信息页面，并看到那本书。否则用户将看到一个根据他关键字的搜索结果。在下一个例子里。一个新的路由将被创建。它将口占RouteBase类。均需一个更复杂的路由。将用一个子域名替代在域名后边输入书名。例如 http://mvc3book.localhost/ 将返回上述图书的详细内容-MVC3编程的20个秘方。

为了让这成为可能，BOOK model 需要被更新去包含一个新的参数，名为“ShortName”。      此参数将被用来作为子域，并允许书籍通过创建扩展的RouteBase类的类进行搜索。

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using System; using System.Collections.Generic; using System.Linq; using System.Web; using System.ComponentModel.DataAnnotations; using MvcApplication.Validations;   namespace MvcApplication.Models {     public class Book     {         public int ID { get; set; }           [Required]         public string ShortName { get; set; }           [Required]         [Display(Name = "TitleDisplay", ResourceType = typeof(Resources.Resource1))]         public string Title { get; set; }           [Display(Name = "IsbnDisplay", ResourceType = typeof(Resources.Resource1))]         [Required]         [IsbnValidation]         public string Isbn { get; set; }           [Display(Name = "SummaryDisplay", ResourceType = typeof(Resources.Resource1))]         [Required]         public string Summary { get; set; }           [Display(Name = "AuthorDisplay", ResourceType = typeof(Resources.Resource1))]         [Required]         public string Author { get; set; }           [Display(Name = "ThumbnailDisplay", ResourceType = typeof(Resources.Resource1))]         public string Thumbnail { get; set; }           [Display(Name = "PriceDisplay", ResourceType = typeof(Resources.Resource1))]         [Range(1, 100)]         public double Price { get; set; }           [Display(Name = "PublishedDisplay", ResourceType = typeof(Resources.Resource1))]         [DataType(DataType.Date)]         [Required]         public DateTime Published { get; set; }     }   }

 

现在必须创建一个新的类将包含新的路由背后的逻辑。选择Utils文件夹中，右键单击并选择“添加→类。这个新的类将被称为 BookDomainRoute.cs。下面的类将从Request.Headers为当前HttpContext检索域名。该域名将被.”操作符的分成 “数组。执行一些错误检查以确保我们有一个子域名不是WWW。

第一块子域，例如，ShortName，是用来执行书本上表的搜索，找到特定书籍。如果查找到了书籍，创建一个新的对象类RouteData，设置 Controller为Books，Action 设置为Detail，最后的ID是这本书的ID。如果没有找到书籍，主页将显示出来。在下面的例子，它可以很容易改变以直接导航用户到一个错误页或根据 Keyword 跳转到Books/index 页（在前面的例子）。

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using System; using System.Collections.Generic; using System.Linq; using System.Web; using System.Web.Routing; using System.Web.Mvc; using MvcApplication.Models;   namespace MvcApplication.Utils {     public class BookDomainRoute : RouteBase     {         private BookDBContext db = new BookDBContext();           public override RouteData GetRouteData(HttpContextBase httpContext)         {             // Get the domain name             var url = httpContext.Request.Url.Authority;             // Split into array of parts             var pieces = url.Split('.');                // Ensure there is a subdomain and it's not www             if (pieces.Length < 2 && pieces[0] != "www")             {                 return null;             }               string ShortName = pieces[0];                // Find the book by ShortName             var books = from b in db.Books select b;             books = books.Where(b => b.ShortName.ToUpper().Contains(ShortName.ToUpper()));               // Check to make sure a book was found             if (books.Count() == 0)             {                 return null;             }               // Get the first result             Book book = books.First();               // Set the route data             RouteData routeData = new RouteData(this, new MvcRouteHandler());             routeData.Values.Add("controller", "Books");             routeData.Values.Add("action", "Details");             routeData.Values.Add("id", book.ID);               return routeData;         }            public override VirtualPathData GetVirtualPath(RequestContext requestContext, RouteValueDictionary values)         {             return null;         }     } }

 

最后Global.asax.cs文件必须再次更新，包括新创建的路由。为了使新的路由类可以找到。需要添加using语句到utils目录。

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using System; using System.Collections.Generic; using System.Linq; using System.Web; using System.Web.Mvc; using System.Web.Routing; using MvcApplication.Models; using System.Data.Entity; using System.Globalization; using System.Threading; using MvcApplication.Utils;   namespace MvcApplication {     // Note: For instructions on enabling IIS6 or IIS7 classic mode,     // visit http://go.microsoft.com/?LinkId=9394801       public class MvcApplication : System.Web.HttpApplication     {         public static void RegisterGlobalFilters(GlobalFilterCollection filters)         {             filters.Add(new HandleErrorAttribute());         }           public static void RegisterRoutes(RouteCollection routes)         {             routes.IgnoreRoute("{resource}.axd/{*pathInfo}");               routes.Add(new BookDomainRoute());               routes.MapRoute(                 "BookName", // Route name                 "{Keyword}", // URL with parameters                 new { controller = "Books", action = "Index", id = UrlParameter.Optional }, // Parameter defaults                 new { Keyword = "w+" });               routes.MapRoute(                 "Default", // Route name                 "{controller}/{action}/{id}", // URL with parameters                 new { controller = "Home", action = "Index", id = UrlParameter.Optional } // Parameter defaults             );           }           protected void Application_Start()         {             Database.SetInitializer<BookDBContext>(new BookInitializer());               AreaRegistration.RegisterAllAreas();               RegisterGlobalFilters(GlobalFilters.Filters);             RegisterRoutes(RouteTable.Routes);               String connectionString = System.Configuration.ConfigurationManager.ConnectionStrings["BooksDBContext"].ConnectionString;             System.Web.Caching.SqlCacheDependencyAdmin.EnableNotifications(connectionString);             System.Web.Caching.SqlCacheDependencyAdmin.EnableTableForNotifications(connectionString, "Books");         }           protected void Application_AcquireRequestState(object sender, EventArgs e)         {             if (HttpContext.Current.Session != null)             {                 CultureInfo ci = (CultureInfo)this.Session["CurrentLanguage"];                 if (ci == null)                 {                     ci = new CultureInfo("en");                     this.Session["CurrentLanguage"] = ci;                 }                     Thread.CurrentThread.CurrentUICulture = ci;                 Thread.CurrentThread.CurrentCulture = CultureInfo.CreateSpecificCulture(ci.Name);             }         }     } }

 

上述的例子包含良好的使用路由的伟大的开始。两者都可以很容易地更新执行其他路由，例如，子域名可以用来显示用户的特定的个人资料页，或以前实施的多语种秘方可更新为使用一个路由类允许象en.example.com或fr.example.com一样的URL设置当前的语言文化。