asp.net mvc路由篇 如何找到 IHttpHandler方法介绍
2024-07-10 12:41:19
供稿：网友
学习是使用asp.net已经有很长一段时间了，现在就来分析一下mvc的整过过程吧。个人计划写一个mvc系列的博文，仅从源代码的角度来分析mvc。在接触mvc时我们一定会经历路由，那么路由这东东是怎么搞出来的啊。在我们的web.config中有这么一句： <add assembly="System.Web.Routing, Version=4.0.0.0, Culture=neutral, PublicKeyToken=31BF3856AD364E35" /> 看来路由是它咋负责了。在这个dll中有一个很特殊的类UrlRoutingModule
我们来看看它里面主要的核心代码吧：
代码如下:
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);
}
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);
}
}
}
}
在IHttpModule.Init中注册了一个PostResolveRequestCache事件，而该事件主要是调用PostResolveRequestCache这个方法，在这个方法里面有几句很重要的代码是
代码如下:
RouteData routeData = this.RouteCollection.GetRouteData(context);
IRouteHandler routeHandler = routeData.RouteHandler;
RequestContext requestContext = new RequestContext(context, routeData);
context.Request.RequestContext = requestContext;
IHttpHandler httpHandler = routeHandler.GetHttpHandler(requestContext);
context.RemapHandler(httpHandler);
让我们来分析第一句RouteData routeData = this.RouteCollection.GetRouteData(context) ，这句我们猜测是获取路由信息。要想理解这句代码又得回到我们程序中来，我们在Global.asax.cs文件中的RegisterRoutes方法中，默认有这么一句
