.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 }
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 }
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
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