UrlRoutingModel摘要

 在机器级别(C:\WINDOWS\Microsoft.NET\Framework\v4.0.30319\Config)的web.config中与如下HttpModule配置

 <add name="UrlRoutingModule-4.0" type="System.Web.Routing.UrlRoutingModule" />

该模块代码

---------------

[TypeForwardedFrom("System.Web.Routing, Version=3.5.0.0, Culture=Neutral, PublicKeyToken=31bf3856ad364e35")]
public class UrlRoutingModule : IHttpModule
{
    // Fields
    private static readonly object _contextKey = new object();
    private static readonly object _requestDataKey = new object();
    private RouteCollection _routeCollection;

    // Methods
    protected virtual void Dispose()
    {
    }

    protected virtual void Init(HttpApplication application)
    {
        if (application.Context.Items[_contextKey] == null)
        {
            application.Context.Items[_contextKey] = _contextKey;
            application.PostResolveRequestCache += new EventHandler(this.OnApplicationPostResolveRequestCache);
        }
    }

    private void OnApplicationPostResolveRequestCache(object sender, EventArgs e)
    {
        HttpContextBase context = new HttpContextWrapper(((HttpApplication) sender).Context);
        this.PostResolveRequestCache(context);
    }

    [Obsolete("This method is obsolete. Override the Init method to use the PostMapRequestHandler event.")]
    public virtual void PostMapRequestHandler(HttpContextBase context)
    {
    }

    public virtual void PostResolveRequestCache(HttpContextBase context)
    {
        RouteData routeData = this.RouteCollection.GetRouteData(context);
        if (routeData != null)
        {
            IRouteHandler routeHandler = routeData.RouteHandler;
            if (routeHandler == null) throw new InvalidOperationException(string.Format(CultureInfo.CurrentUICulture, SR.GetString("UrlRoutingModule_NoRouteHandler"), new object[0]));
            if (!(routeHandler is StopRoutingHandler))
            {
                RequestContext requestContext = new RequestContext(context, routeData);
                context.Request.RequestContext = requestContext;
                IHttpHandler httpHandler = routeHandler.GetHttpHandler(requestContext);
                if (httpHandler == null) throw new InvalidOperationException(string.Format(CultureInfo.CurrentUICulture, SR.GetString("UrlRoutingModule_NoHttpHandler"), new object[] { routeHandler.GetType() }));
                if (httpHandler is UrlAuthFailureHandler)
                {
                    if (!FormsAuthenticationModule.FormsAuthRequired) throw new HttpException(0x191, SR.GetString("Assess_Denied_Description3"));
                    UrlAuthorizationModule.ReportUrlAuthorizationFailure(HttpContext.Current, this);
                }
                else
                    context.RemapHandler(httpHandler);
            }
        }
    }

    void IHttpModule.Dispose()
    {
        this.Dispose();
    }

    void IHttpModule.Init(HttpApplication application)
    {
        this.Init(application);
    }

    // Properties
    public RouteCollection RouteCollection
    {
        get
        {
            if (this._routeCollection == null) this._routeCollection = RouteTable.Routes;
            return this._routeCollection;
        }
        set
        {
            this._routeCollection = value;
        }
    }
}

 

该模块负责将对应的请求(URL)，路由到指定的httpHandler,而httpHandler则由IRouteHandler创建立， 每个Route规则可以指定一个IRouteHandler

MVCRouteHandler代码

namespace System.Web.Mvc {
    using System.Web.Routing;

    public class MvcRouteHandler : IRouteHandler {
        protected virtual IHttpHandler GetHttpHandler(RequestContext requestContext) {
            return new MvcHandler(requestContext);
        }

        #region IRouteHandler Members
        IHttpHandler IRouteHandler.GetHttpHandler(RequestContext requestContext) {
            return GetHttpHandler(requestContext);
        }
        #endregion
    }
}

MVCRouteHandler的任务是创建立MvcHandler

PageRouteHandler代码

public class PageRouteHandler : IRouteHandler
{
    // Fields
    private Route _routeVirtualPath;
    private bool _useRouteVirtualPath;

    // Methods
    public PageRouteHandler(string virtualPath) : this(virtualPath, true)
    {
    }

    public PageRouteHandler(string virtualPath, bool checkPhysicalUrlAccess)
    {
        if (string.IsNullOrEmpty(virtualPath) || !virtualPath.StartsWith("~/", StringComparison.OrdinalIgnoreCase)) throw new ArgumentException(SR.GetString("PageRouteHandler_InvalidVirtualPath"), "virtualPath");
        this.VirtualPath = virtualPath;
        this.CheckPhysicalUrlAccess = checkPhysicalUrlAccess;
        this._useRouteVirtualPath = this.VirtualPath.Contains("{");
    }

    private bool CheckUrlAccess(string virtualPath, RequestContext requestContext)
    {
        IPrincipal user = requestContext.HttpContext.User;
        if (user == null) user = new GenericPrincipal(new GenericIdentity(string.Empty, string.Empty), new string[0]);
        return this.CheckUrlAccessWithAssert(virtualPath, requestContext, user);
    }

    [SecurityPermission(SecurityAction.Assert, Unrestricted=true)]
    private bool CheckUrlAccessWithAssert(string virtualPath, RequestContext requestContext, IPrincipal user)
    {
        return UrlAuthorizationModule.CheckUrlAccessForPrincipal(virtualPath, user, requestContext.HttpContext.Request.HttpMethod);
    }

    public virtual IHttpHandler GetHttpHandler(RequestContext requestContext)
    {
        if (requestContext == null) throw new ArgumentNullException("requestContext");
        string substitutedVirtualPath = this.GetSubstitutedVirtualPath(requestContext);
        int index = substitutedVirtualPath.IndexOf('?');
        if (index != -1) substitutedVirtualPath = substitutedVirtualPath.Substring(0, index);
        if (this.CheckPhysicalUrlAccess && !this.CheckUrlAccess(substitutedVirtualPath, requestContext)) return new UrlAuthFailureHandler();
        return (BuildManager.CreateInstanceFromVirtualPath(substitutedVirtualPath, typeof(Page)) as Page);
    }

    public string GetSubstitutedVirtualPath(RequestContext requestContext)
    {
        if (requestContext == null) throw new ArgumentNullException("requestContext");
        if (!this._useRouteVirtualPath) return this.VirtualPath;
        VirtualPathData virtualPath = this.RouteVirtualPath.GetVirtualPath(requestContext, requestContext.RouteData.Values);
        if (virtualPath == null) return this.VirtualPath;
        return ("~/" + virtualPath.VirtualPath);
    }

    // Properties
    public bool CheckPhysicalUrlAccess { get; private set; }

    private Route RouteVirtualPath
    {
        get
        {
            if (this._routeVirtualPath == null) this._routeVirtualPath = new Route(this.VirtualPath.Substring(2), this);
            return this._routeVirtualPath;
        }
    }

    public string VirtualPath { get; private set; }
}

改模块通过BuilerManger来创建Aspx页面对象实例类,创建时会使用机器级的HttpHandlers配置中的页面工厂

<add path="*.aspx" verb="*" type="System.Web.UI.PageHandlerFactory" validate="True" />

调用RouteTable.Routes.MapPageRoute(...)时，会注册一个RouteHandler为PageRouteHanler的Route规则

public Route MapPageRoute(string routeName, string routeUrl, string physicalFile, bool checkPhysicalUrlAccess, RouteValueDictionary defaults, RouteValueDictionary constraints, RouteValueDictionary dataTokens)
{
    if (routeUrl == null) throw new ArgumentNullException("routeUrl");
    Route item = new Route(routeUrl, defaults, constraints, dataTokens, new PageRouteHandler(physicalFile, checkPhysicalUrlAccess));
    this.Add(routeName, item);
    return item;
}