半路独行

.Net MVC5路由机制与扩展

新建一个MVC项目启动后,首先访问的地址是http://localhost:xxx/Home/Index,这时候我们也明白因为在程序中有个叫做Home的控制器,并且在这个控制器下面有个叫做Index的方法,基于这种对应的关系,才有了这种结果,那么这种对应关系是如何产生,如何工作的了?

在我们网站在第一次启动的时候,会去访问一个全局的配置文件Global.asax下面的Application_Start()方法,代码如下

 1 using System;
 2 using System.Collections.Generic;
 3 using System.Linq;
 4 using System.Web;
 5 using System.Web.Mvc;
 6 using System.Web.Optimization;
 7 using System.Web.Routing;
 8 
 9 namespace Test
10 {
11     public class MvcApplication : System.Web.HttpApplication
12     {
13         protected void Application_Start()
14         {
15             AreaRegistration.RegisterAllAreas();
16             FilterConfig.RegisterGlobalFilters(GlobalFilters.Filters);
17             RouteConfig.RegisterRoutes(RouteTable.Routes);
18             BundleConfig.RegisterBundles(BundleTable.Bundles);
19         }
20     }
21 }

在这个方法中就注册了我们的路由配置,相关的注册文件都是在在App_Start目录下

 路由配置文件RouteConfig.cs,内容如下

 1 using System;
 2 using System.Collections.Generic;
 3 using System.Linq;
 4 using System.Web;
 5 using System.Web.Mvc;
 6 using System.Web.Routing;
 7 
 8 namespace Test
 9 {
10     public class RouteConfig
11     {
12         public static void RegisterRoutes(RouteCollection routes)
13         {
14             routes.IgnoreRoute("{resource}.axd/{*pathInfo}");
15 
16             routes.MapRoute(
17                 name: "Default",
18                 url: "{controller}/{action}/{id}",
19                 defaults: new { controller = "Home", action = "Index", id = UrlParameter.Optional }
20             );
21         }
22     }
23 }

首先是忽略路由,满足匹配会被忽略,如果没有特殊需求,这个地方就不需要更改,

name表示路由的名称,同一个路由集合中,路由名称必须唯一,不能够有重名,

url就是正则表达式,用于http://localhost:xxx/后路径地址的匹配,

defaults表示缺省路由,也就是默认的路由.这是一个路由规则增删的方法,并且默认的路由为home/index,

还有一个比较常用的参数是constraints,用于条件约束,简单实例如下:

 1     public class RouteConfig
 2     {
 3         public static void RegisterRoutes(RouteCollection routes)
 4         {
 5             routes.IgnoreRoute("{resource}.axd/{*pathInfo}");
 6 
 7             //假若Home下有Test(int year,int month,int day)方法
 8             //home/Test_2017_06_05可以访问至该方法
 9             //home/Test_2017_6_05是无法访问
10             routes.MapRoute(
11               name: "Constraints",
12               url: "{controller}/{action}_{year}_{month}_{day}",
13               defaults: new { controller = "Home", action = "Index", id = UrlParameter.Optional },
14               //条件参数,约束后面参数(此处简单正则:4位数字,2位数字,2位数字)
15               constraints: new { year = @"^\d{4}", month = @"^\d{2}", day = @"^\d{2}" });
16 
17             routes.MapRoute(
18                 name: "Default",
19                 url: "{controller}/{action}/{id}",
20                 defaults: new { controller = "Home", action = "Index", id = UrlParameter.Optional });
21         }
22     }

 

路由浅析

那么路由究竟是如何工作的,下面是2个与路由工作十分紧密的2个方法的源码,任何http请求进入后,都会先被它们处理

 1 public virtual void PostResolveRequestCache(HttpContextBase context)
 2     {
 3         RouteData routeData = RouteCollection.GetRouteData(context);
 4         if (routeData != null)
 5         {
 6             IRouteHandler routeHandler = routeData.RouteHandler;
 7             if (routeHandler == null)
 8             {
 9                 throw new InvalidOperationException(string.Format(CultureInfo.CurrentCulture, SR.GetString("UrlRoutingModule_NoRouteHandler")));
10             }
11             if (!(routeHandler is StopRoutingHandler))
12             {
13                 RequestContext requestContext = new RequestContext(context, routeData);
14                 context.Request.RequestContext = requestContext;
15                 IHttpHandler httpHandler = routeHandler.GetHttpHandler(requestContext);
16                 if (httpHandler == null)
17                 {
18                     throw new InvalidOperationException(string.Format(CultureInfo.CurrentUICulture, SR.GetString("UrlRoutingModule_NoHttpHandler"), new object[1]
19                     {
20                         routeHandler.GetType()
21                     }));
22                 }
23                 if (httpHandler is UrlAuthFailureHandler)
24                 {
25                     if (FormsAuthenticationModule.FormsAuthRequired)
26                     {
27                         UrlAuthorizationModule.ReportUrlAuthorizationFailure(HttpContext.Current, this);
28                         return;
29                     }
30                     throw new HttpException(401, SR.GetString("Assess_Denied_Description3"));
31                 }
32                 context.RemapHandler(httpHandler);
33             }
34         }
35     }
PostResolveRequestCache
 1 public RouteData GetRouteData(HttpContextBase httpContext)
 2 {
 3     if (httpContext == null)
 4     {
 5         throw new ArgumentNullException("httpContext");
 6     }
 7     if (httpContext.Request == null)
 8     {
 9         throw new ArgumentException(SR.GetString("RouteTable_ContextMissingRequest"), "httpContext");
10     }
11     if (base.Count == 0)
12     {
13         return null;
14     }
15     bool flag = false;
16     bool flag2 = false;
17     if (!RouteExistingFiles)
18     {
19         flag = IsRouteToExistingFile(httpContext);
20         flag2 = true;
21         if (flag)
22         {
23             return null;
24         }
25     }
26     using (GetReadLock())
27     {
28         foreach (RouteBase item in this)
29         {
30             RouteData routeData = item.GetRouteData(httpContext);
31             if (routeData != null)
32             {
33                 if (!item.RouteExistingFiles)
34                 {
35                     if (!flag2)
36                     {
37                         flag = IsRouteToExistingFile(httpContext);
38                         flag2 = true;
39                     }
40                     if (flag)
41                     {
42                         return null;
43                     }
44                 }
45                 return routeData;
46             }
47         }
48     }
49     return null;
50 }
GetRouteData

大致分析下这段源码,我们可以得出下列比较重要的结论

1在路由匹配之前,先一步检查了物理文件的存在,所以mvc和webform可以共存,如果存在满足路径条件的aspx文件,它会优先被访问

2路由是从上到下逐个匹配的,所以排列的顺序对于路由匹配是非常重要的

 

 路由扩展

在上述基础下,我们对路由有了大概的了解,对此我们可以简单扩展一下

路由并不是只能够在路径规则上做文章,我们也可以继承路由的基类RouteBase自定义一些路由,然后把自定义的路由放入注册路由集合中,调准好顺序,实现我们想要的结果.因为能够得到HttpContext这个用户请求的上下文,我们可以完成很多扩展,例如检查ip,浏览器类型,参数等等,下面我们就简单的实现不同浏览器访问到不同路径的功能,如下:

 1     public class RouteConfig
 2     {
 3         public static void RegisterRoutes(RouteCollection routes)
 4         {
 5             routes.IgnoreRoute("{resource}.axd/{*pathInfo}");
 6 
 7             //注意顺序
 8             routes.Add("Agent",new Agent());
 9 
10             routes.MapRoute(
11                 name: "Default",
12                 url: "{controller}/{action}/{id}",
13                 defaults: new { controller = "Home", action = "Index", id = UrlParameter.Optional });
14         }
15 
16       
17     }
18     public class Agent : RouteBase
19     {
20         public override RouteData GetRouteData(HttpContextBase httpContext)
21         {
22             if (httpContext.Request.UserAgent.Contains("Chrome/63.0.3239.132"))
23             {
24                 var data = new RouteData(this, new MvcRouteHandler());
25                 data.Values.Add("controller", "Home");
26                 data.Values.Add("action", "About");
27                 return data;
28             }
29             else
30             {
31                 return null;
32             }
33         }
34 
35         public override VirtualPathData GetVirtualPath(RequestContext requestContext, RouteValueDictionary values)
36         {
37             return null;
38         }
39     }

一定得注意路由排列的顺序,如果将上面的Agent路由放在Default路由后面,那么就直接会访问到Home/Index,而不会去判断.

 

我们也可以通过自定义继承了RouteBase的Route类,来完成特殊路径的扩展,如下

 1   public class RouteConfig
 2     {
 3         public static void RegisterRoutes(RouteCollection routes)
 4         {
 5             routes.IgnoreRoute("{resource}.axd/{*pathInfo}");
 6 
 7             routes.Add(new Route("Test",new TestRouteHandler()));
 8 
 9             routes.MapRoute(
10                 name: "Default",
11                 url: "{controller}/{action}/{id}",
12                 defaults: new { controller = "Home", action = "Index", id = UrlParameter.Optional });
13         }
14     }
15 
16     public class TestRouteHandler : IRouteHandler
17     {
18         public IHttpHandler GetHttpHandler(RequestContext requestContext)
19         {
20             return new TestHandler();
21         }
22     }
23     public class TestHandler : IHttpHandler
24     {
25         public bool IsReusable => true;
26 
27         public void ProcessRequest(HttpContext context)
28         {
29             context.Response.Write("Test");
30         }
31     }

效果如下:

 

出自:博客园-半路独行

 原文地址:https://www.cnblogs.com/banluduxing/p/9185159.html

 本文出自于http://www.cnblogs.com/banluduxing 转载请注明出处。

 

posted @ 2018-06-23 12:41  半路独行  阅读(787)  评论(0编辑  收藏  举报