Asp.net MVC Route初探

2010-09-05 20:42 空逸云閱讀(735) 評論(1) 收藏舉報

Asp.net MVC天生就有著漂亮的Url.但是卻有別于Asp.net的UrlRewriter.那么其的實現原理是怎樣的呢?這就要說到Route了.

Asp.Net MVC生命周期

Asp.net MVC的生命周期由8個步驟組成:

1.RouteTable(路由表)的創建

2.UrlRoutingMoudle請求攔截

3.Routing engine確定route

4.RouteHandler創建相關的IHttpHandler實例

5.IHttpHandler實例確定Controller(控制器)

6.Controller執行

7.視圖引擎創建

8.視圖呈現

這里主要講解前4個.

RouteTable(路由表)的創建

打開Global.asax

 1: public class MvcApplication : System.Web.HttpApplication

 2: {

 3: public static void RegisterRoutes(RouteCollection routes)

 4: {

 5: routes.IgnoreRoute("{resource}.axd/{*pathInfo}");

6:

 7: routes.MapRoute(

 8: "Default", // Route name

 9: "{controller}/{action}/{id}", // URL with parameters

 10: new { controller = "Home", action = "Index", id = UrlParameter.Optional }, // Parameter defaults

 11: new { controller = @"[^\.]*"}

 12: );

13:

 14: routes.MapRoute(

 15: "Defalut",

 16: "{controller}/Blog/{date}",

 17: new { action = "Blog" },

 18: new { date = @"^\d{4}\.\d{2}\.\d{2}" }

 19: );

 20: }

21:

 22: protected void Application_Start()

 23: {

 24: AreaRegistration.RegisterAllAreas();

25:

 26: RegisterRoutes(RouteTable.Routes);

27:

 28: //RouteDebug.RouteDebugger.RewriteRoutesForTesting(RouteTable.Routes);

 29: }

 30: }

在此,我們聲明了兩個Route.

在MVC1中.我們必須

 1: routes.Add(new Route("User/Login", new RouteValueDictionary(new { controller = "User", action = "Login" }), new MvcRouteHandler()));

 2: routes.Add(new Route("User/Logout", new RouteValueDictionary(new { controller = "User", action = "Logout" }), new MvcRouteHandler()));

 3: routes.Add(new Route("User/Signup", new RouteValueDictionary(new { controller = "User", action = "Signup" }), new MvcRouteHandler()));

這樣添加.但在.Net3.5中.我們卻可以直接利用匿名類直接New一個.這是因為.Net3.5中擴展了一個MapRoute方法.該方法利用反射.進行背后的添加

 1: public static Route MapRoute(this RouteCollection routes, string name, string url, object defaults, object constraints, string[] namespaces) {

 2: if (routes == null) {

 3: throw new ArgumentNullException("routes");

 4: }

 5: if (url == null) {

 6: throw new ArgumentNullException("url");

 7: }

8:

 9: Route route = new Route(url, new MvcRouteHandler()) {

 10: Defaults = new RouteValueDictionary(defaults),

 11: Constraints = new RouteValueDictionary(constraints),

 12: DataTokens = new RouteValueDictionary()

 13: };

14:

 15: if ((namespaces != null) && (namespaces.Length > 0)) {

 16: route.DataTokens["Namespaces"] = namespaces;

 17: }

18:

 19: routes.Add(name, route);

20:

 21: return route;

 22: }

UrlRoutingMoudle請求攔截

按照MS慣例,一般會在WebConfig留下些蛛絲馬跡,打開WebConfig.不出其然.我們發現HttpMoudle中有

 1: <add name="UrlRoutingModule" type="System.Web.Routing.UrlRoutingModule, System.Web.Routing, Version=3.5.0.0, Culture=neutral, PublicKeyToken=31BF3856AD364E35"/>

利用Reflector打開UrlRoutingModule類.

 1: protected virtual void Init(HttpApplication application)

 2: {

 3: application.PostResolveRequestCache += new EventHandler(this.OnApplicationPostResolveRequestCache);

 4: application.PostMapRequestHandler += new EventHandler(this.OnApplicationPostMapRequestHandler);

 5: }

6:

7:

Routing engine確定route

可以看到.在application的events中注冊了PostResolveRequestCache 和PostMapRequestHandler 事件.

PostResolveRequestCache

 1: public virtual void PostResolveRequestCache(HttpContextBase context)

 2: {

 3: RouteData routeData = this.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.CurrentUICulture, RoutingResources.UrlRoutingModule_NoRouteHandler, new object[0]));

 10: }

 11: if (!(routeHandler is StopRoutingHandler))

 12: {

 13: RequestContext requestContext = new RequestContext(context, routeData);

 14: IHttpHandler httpHandler = routeHandler.GetHttpHandler(requestContext);

 15: if (httpHandler == null)

 16: {

 17: throw new InvalidOperationException(string.Format(CultureInfo.CurrentUICulture, RoutingResources.UrlRoutingModule_NoHttpHandler, new object[] { routeHandler.GetType() }));

 18: }

 19: context.Items[_requestDataKey] = new RequestData { OriginalPath = context.Request.Path, HttpHandler = httpHandler };

 20: context.RewritePath("~/UrlRouting.axd");

 21: }

 22: }

 23: }

24:

25:

這里.首先通過RouteCollection.GetRouteData得到當前的RouteData,

UrlRoutingModule.RouteCollection

 1: public RouteCollection RouteCollection

 2: {

 3: get

 4: {

 5: if (this._routeCollection == null)

 6: {

 7: this._routeCollection = RouteTable.Routes;

 8: }

 9: return this._routeCollection;

 10: }

 11: set

 12: {

 13: this._routeCollection = value;

 14: }

 15: }

16:

module中的RouteCollection只是很簡單的引用了RouteTable中的靜態實例Routes而已.

RouteTable

public class RouteTable

{

// Fields

private static RouteCollection _instance = new RouteCollection();

  

// Properties

public static RouteCollection Routes

{

get

{

return _instance;

}

}

}

RouteCollection.GetRouteData

這是獲取RouteDate的核心實現.

 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(RoutingResources.RouteTable_ContextMissingRequest, "httpContext");

 10: }

 11: if (!this.RouteExistingFiles)

 12: {

 13: string appRelativeCurrentExecutionFilePath = httpContext.Request.AppRelativeCurrentExecutionFilePath;

 14: if (((appRelativeCurrentExecutionFilePath != "~/") && (this._vpp != null)) && (this._vpp.FileExists(appRelativeCurrentExecutionFilePath) || this._vpp.DirectoryExists(appRelativeCurrentExecutionFilePath)))

 15: {

 16: return null;

 17: }

 18: }

 19: using (this.GetReadLock())//線程鎖

 20: {

 21: foreach (RouteBase base2 in this)//遍歷當前集合中的所有RouteBase

 22: {

 23: RouteData routeData = base2.GetRouteData(httpContext); //調用RouteBase的RouteData.此處傳入的Class是Route.

 24: if (routeData != null)

 25: {

 26: return routeData;

 27: }

 28: }

 29: }

 30: return null;

 31: }

32:

Route

Route繼承至RouteBase.Route中提供了MVC的Route信息.

可以看到最后承載Route數據的容器是RouteVallueDictionary.Route中包含了該Dictionary

RouteData

RouteData的實現很簡單.就提供了幾個基本的字段而已.主要用于描述當前Route數據的信息.如此一來.我們可以得到當前Url所匹配的Route.

 1: public class RouteData

 2: {

 3: // Fields

 4: private RouteValueDictionary _dataTokens;

 5: private IRouteHandler _routeHandler;

 6: private RouteValueDictionary _values;

7:

 8: // Methods

 9: public RouteData();

 10: public RouteData(RouteBase route, IRouteHandler routeHandler);

 11: public string GetRequiredString(string valueName);

12:

 13: // Properties

 14: public RouteValueDictionary DataTokens { get; }

 15: public RouteBase Route { get; set; }

 16: public IRouteHandler RouteHandler { get; set; }

 17: public RouteValueDictionary Values { get; }

 18: }

RouteHandler創建相關的IHttpHandler實例

RouteHandler

得到RouteData之后.獲取RouteData之中的RouteHandler.根據RouteHandler獲取相關的IHttpHandler.這樣.MVC的Route隱射階段就已經完成
 1: RequestContext requestContext = new RequestContext(context, routeData);
 2: IHttpHandler httpHandler = routeHandler.GetHttpHandler(requestContext);

后面就是Controller的確定和執行了.

刷新頁面返回頂部

空逸云路漫漫其修遠兮,吾將上下而求索.

Asp.net MVC Route初探

Asp.Net MVC生命周期

RouteTable(路由表)的創建

UrlRoutingMoudle請求攔截

Routing engine確定route

UrlRoutingModule.RouteCollection

RouteTable

RouteCollection.GetRouteData

Route

RouteData

RouteHandler創建相關的IHttpHandler實例

RouteHandler

About

空逸云 路漫漫其修遠兮,吾將上下而求索.

Asp.net MVC Route初探

Asp.Net MVC生命周期

RouteTable(路由表)的創建

UrlRoutingMoudle請求攔截

Routing engine確定route

UrlRoutingModule.RouteCollection

RouteTable

RouteCollection.GetRouteData

Route

RouteData

RouteHandler創建相關的IHttpHandler實例

RouteHandler

About

空逸云路漫漫其修遠兮,吾將上下而求索.