上一节说在urlroutingmodule中mvchandler 映射到httpcontext上，那mvchandler又是怎么执行的呢？
（1）、httpruntime
Processrequest方法
// System.Web.HttpRuntime
[AspNetHostingPermission(SecurityAction.Demand, Level = AspNetHostingPermissionLevel.Medium)]
public static void ProcessRequest(HttpWorkerRequest wr)
{
if (wr == null)
{
throw new ArgumentNullException("wr");
}
//是否集成模式
if (HttpRuntime.UseIntegratedPipeline)
{
throw new PlatformNotSupportedException(SR.GetString("Method_Not_Supported_By_Iis_Integrated_Mode", new object[]
{
"HttpRuntime.ProcessRequest"
}));
}
HttpRuntime.ProcessRequestNoDemand(wr);
}
ProcessRequestNoDemand(wr)方法
// System.Web.HttpRuntime
internal static void ProcessRequestNoDemand(HttpWorkerRequest wr)
{
//获取请求队列
RequestQueue requestQueue = HttpRuntime._theRuntime._requestQueue;
wr.UpdateInitialCounters();
if (requestQueue != null)
{
wr = requestQueue.GetRequestToExecute(wr);
}
if (wr != null)
{
HttpRuntime.CalculateWaitTimeAndUpdatePerfCounter(wr);
wr.ResetStartTime();
HttpRuntime.ProcessRequestNow(wr);
}
}
ProcessRequestNow(wr)方法
// System.Web.HttpRuntime
internal static void ProcessRequestNow(HttpWorkerRequest wr)
{
HttpRuntime._theRuntime.ProcessRequestInternal(wr);
}
ProcessRequestInternal(wr)方法
// System.Web.HttpRuntime
private void ProcessRequestInternal(HttpWorkerRequest wr)
{
//活动请求数量增加
Interlocked.Increment(ref this._activeRequestCount);
//判断请求数异常
if (this._disposingHttpRuntime)
{
try
{
wr.SendStatus(503, "Server Too Busy");
wr.SendKnownResponseHeader(12, "text/html; charset=utf-8");
byte[] bytes = Encoding.ASCII.GetBytes("<html><body>Server Too Busy</body></html>");
wr.SendResponseFromMemory(bytes, bytes.Length);
wr.FlushResponse(true);
wr.EndOfRequest();
}
finally
{
Interlocked.Decrement(ref this._activeRequestCount);
}
return;
}
HttpContext httpContext;
try
{
//HttpWorkerRequest转HttpContext
httpContext = new HttpContext(wr, false);
}
catch
{
try
{
wr.SendStatus(400, "Bad Request");
wr.SendKnownResponseHeader(12, "text/html; charset=utf-8");
byte[] bytes2 = Encoding.ASCII.GetBytes("<html><body>Bad Request</body></html>");
wr.SendResponseFromMemory(bytes2, bytes2.Length);
wr.FlushResponse(true);
wr.EndOfRequest();
return;
}
finally
{
Interlocked.Decrement(ref this._activeRequestCount);
}
}
wr.SetEndOfSendNotification(this._asyncEndOfSendCallback, httpContext);
HostingEnvironment.IncrementBusyCount();
try
{
try
{
this.EnsureFirstRequestInit(httpContext);
}
catch
{
if (!httpContext.Request.IsDebuggingRequest)
{
throw;
}
}
httpContext.Response.InitResponseWriter();
//获取application实例
IHttpHandler applicationInstance = HttpApplicationFactory.GetApplicationInstance(httpContext);
if (applicationInstance == null)
{
throw new HttpException(SR.GetString("Unable_create_app_object"));
}
if (EtwTrace.IsTraceEnabled(5, 1))
{
EtwTrace.Trace(EtwTraceType.ETW_TYPE_START_HANDLER, httpContext.WorkerRequest, applicationInstance.GetType().FullName, "Start");
}
//判断application实例是否有继承IHttpAsyncHandler
if (applicationInstance is IHttpAsyncHandler)
{
IHttpAsyncHandler httpAsyncHandler = (IHttpAsyncHandler)applicationInstance;
httpContext.AsyncAppHandler = httpAsyncHandler;
//执行application的BeginProcessRequest
httpAsyncHandler.BeginProcessRequest(httpContext, this._handlerCompletionCallback, httpContext);
}
else
{
applicationInstance.ProcessRequest(httpContext);
this.FinishRequest(httpContext.WorkerRequest, httpContext, null);
}
}
catch (Exception e)
{
httpContext.Response.InitResponseWriter();
this.FinishRequest(wr, httpContext, e);
}
}
BeginProcessRequest方法
IAsyncResult IHttpAsyncHandler.BeginProcessRequest(HttpContext context, AsyncCallback cb, object extraData)
{
this._context = context;
this._context.ApplicationInstance = this;
this._stepManager.InitRequest();
this._context.Root();
HttpAsyncResult httpAsyncResult = new HttpAsyncResult(cb, extraData);
this.AsyncResult = httpAsyncResult;
if (this._context.TraceIsEnabled)
{
HttpRuntime.Profile.StartRequest(this._context);
}
//执行步骤
this.ResumeSteps(null);
return httpAsyncResult;
}
ResumeSteps方法
private void ResumeSteps(Exception error)
{
this._stepManager.ResumeSteps(error);
}
this._stepManager 抽象类
internal abstract class StepManager
{
protected HttpApplication _application;
protected bool _requestCompleted;
internal bool IsCompleted
{
get
{
return this._requestCompleted;
}
}
internal StepManager(HttpApplication application)
{
this._application = application;
}
internal abstract void BuildSteps(WaitCallback stepCallback);
internal void CompleteRequest()
{
this._requestCompleted = true;
if (HttpRuntime.UseIntegratedPipeline)
{
HttpContext context = this._application.Context;
if (context != null && context.NotificationContext != null)
{
context.NotificationContext.RequestCompleted = true;
}
}
}
internal abstract void InitRequest();
internal abstract void ResumeSteps(Exception error);
}