asp.net Page事件处理管道

我们知道页面就是一个处理程序，里面的实现非常复杂，网上也有很多资料讲到asp.net的管道处理，有关page的事件处理也不少；这里我就page的事件处理结果如图：





这里的总结来至asp.net本质论。我们也知道page的处理都集中在一个ProcessRequest方法中，该方法最终主要还是调用ProcessRequestMain方法。其主要实现如下：

private void ProcessRequestMain(bool includeStagesBeforeAsyncPoint, bool includeStagesAfterAsyncPoint)
{
try
{
HttpContext context = this.Context;
string str = null;
if (includeStagesBeforeAsyncPoint)
{
if (this.IsInAspCompatMode)
{
AspCompatApplicationStep.OnPageStartSessionObjects();
}
if (this.PageAdapter != null)
{
this._requestValueCollection = this.PageAdapter.DeterminePostBackMode();
if (this._requestValueCollection != null)
{
this._unvalidatedRequestValueCollection = this.PageAdapter.DeterminePostBackModeUnvalidated();
}
}
else
{
this._requestValueCollection = this.DeterminePostBackMode();
if (this._requestValueCollection != null)
{
this._unvalidatedRequestValueCollection = this.DeterminePostBackModeUnvalidated();
}
}
string callbackControlID = string.Empty;
if (this.DetermineIsExportingWebPart())
{
if (!RuntimeConfig.GetAppConfig().WebParts.EnableExport)
{
throw new InvalidOperationException(SR.GetString("WebPartExportHandler_DisabledExportHandler"));
}
str = this.Request.QueryString["webPart"];
if (string.IsNullOrEmpty(str))
{
throw new InvalidOperationException(SR.GetString("WebPartExportHandler_InvalidArgument"));
}
if (string.Equals(this.Request.QueryString["scope"], "shared", StringComparison.OrdinalIgnoreCase))
{
this._pageFlags.Set(4);
}
string str3 = this.Request.QueryString["query"];
if (str3 == null)
{
str3 = string.Empty;
}
this.Request.QueryStringText = str3;
context.Trace.IsEnabled = false;
}
if (this._requestValueCollection != null)
{
if (this._requestValueCollection["__VIEWSTATEENCRYPTED"] != null)
{
this.ContainsEncryptedViewState = true;
}
callbackControlID = this._requestValueCollection["__CALLBACKID"];
if ((callbackControlID != null) && (this._request.HttpVerb == HttpVerb.POST))
{
this._isCallback = true;
}
else if (!this.IsCrossPagePostBack)
{
VirtualPath path = null;
if (this._requestValueCollection["__PREVIOUSPAGE"] != null)
{
try
{
path = VirtualPath.CreateNonRelativeAllowNull(DecryptString(this._requestValueCollection["__PREVIOUSPAGE"], Purpose.WebForms_Page_PreviousPageID));
}
catch
{
this._pageFlags[8] = true;
}
if ((path != null) && (path != this.Request.CurrentExecutionFilePathObject))
{
this._pageFlags[8] = true;
this._previousPagePath = path;
}
}
}
}
if (this.MaintainScrollPositionOnPostBack)
{
this.LoadScrollPosition();
}
if (context.TraceIsEnabled)
{
this.Trace.Write("aspx.page", "Begin PreInit");
}
this.PerformPreInit();
if (context.TraceIsEnabled)
{
this.Trace.Write("aspx.page", "End PreInit");
}
if (context.TraceIsEnabled)
{
this.Trace.Write("aspx.page", "Begin Init");
}
this.InitRecursive(null);
if (context.TraceIsEnabled)
{
this.Trace.Write("aspx.page", "End Init");
}
if (context.TraceIsEnabled)
{
this.Trace.Write("aspx.page", "Begin InitComplete");
}
this.OnInitComplete(EventArgs.Empty);
if (context.TraceIsEnabled)
{
this.Trace.Write("aspx.page", "End InitComplete");
}
if (this.IsPostBack)
{
if (context.TraceIsEnabled)
{
this.Trace.Write("aspx.page", "Begin LoadState");
}
this.LoadAllState();
if (context.TraceIsEnabled)
{
this.Trace.Write("aspx.page", "End LoadState");
this.Trace.Write("aspx.page", "Begin ProcessPostData");
}
this.ProcessPostData(this._requestValueCollection, true);
if (context.TraceIsEnabled)
{
this.Trace.Write("aspx.page", "End ProcessPostData");
}
}
if (context.TraceIsEnabled)
{
this.Trace.Write("aspx.page", "Begin PreLoad");
}
this.OnPreLoad(EventArgs.Empty);
if (context.TraceIsEnabled)
{
this.Trace.Write("aspx.page", "End PreLoad");
}
if (context.TraceIsEnabled)
{
this.Trace.Write("aspx.page", "Begin Load");
}
this.LoadRecursive();
if (context.TraceIsEnabled)
{
this.Trace.Write("aspx.page", "End Load");
}
if (this.IsPostBack)
{
if (context.TraceIsEnabled)
{
this.Trace.Write("aspx.page", "Begin ProcessPostData Second Try");
}
this.ProcessPostData(this._leftoverPostData, false);
if (context.TraceIsEnabled)
{
this.Trace.Write("aspx.page", "End ProcessPostData Second Try");
this.Trace.Write("aspx.page", "Begin Raise ChangedEvents");
}
this.RaiseChangedEvents();
if (context.TraceIsEnabled)
{
this.Trace.Write("aspx.page", "End Raise ChangedEvents");
this.Trace.Write("aspx.page", "Begin Raise PostBackEvent");
}
this.RaisePostBackEvent(this._requestValueCollection);
if (context.TraceIsEnabled)
{
this.Trace.Write("aspx.page", "End Raise PostBackEvent");
}
}
if (context.TraceIsEnabled)
{
this.Trace.Write("aspx.page", "Begin LoadComplete");
}
this.OnLoadComplete(EventArgs.Empty);
if (context.TraceIsEnabled)
{
this.Trace.Write("aspx.page", "End LoadComplete");
}
if (this.IsPostBack && this.IsCallback)
{
this.PrepareCallback(callbackControlID);
}
else if (!this.IsCrossPagePostBack)
{
if (context.TraceIsEnabled)
{
this.Trace.Write("aspx.page", "Begin PreRender");
}
this.PreRenderRecursiveInternal();
if (context.TraceIsEnabled)
{
this.Trace.Write("aspx.page", "End PreRender");
}
}
}
if ((this._legacyAsyncInfo == null) || this._legacyAsyncInfo.CallerIsBlocking)
{
this.ExecuteRegisteredAsyncTasks();
}
this.ValidateRawUrlIfRequired();
if (includeStagesAfterAsyncPoint)
{
if (this.IsCallback)
{
this.RenderCallback();
}
else if (!this.IsCrossPagePostBack)
{
if (context.TraceIsEnabled)
{
this.Trace.Write("aspx.page", "Begin PreRenderComplete");
}
this.PerformPreRenderComplete();
if (context.TraceIsEnabled)
{
this.Trace.Write("aspx.page", "End PreRenderComplete");
}
if (context.TraceIsEnabled)
{
this.BuildPageProfileTree(this.EnableViewState);
this.Trace.Write("aspx.page", "Begin SaveState");
}
this.SaveAllState();
if (context.TraceIsEnabled)
{
this.Trace.Write("aspx.page", "End SaveState");
this.Trace.Write("aspx.page", "Begin SaveStateComplete");
}
this.OnSaveStateComplete(EventArgs.Empty);
if (context.TraceIsEnabled)
{
this.Trace.Write("aspx.page", "End SaveStateComplete");
this.Trace.Write("aspx.page", "Begin Render");
}
if (str != null)
{
this.ExportWebPart(str);
}
else
{
this.RenderControl(this.CreateHtmlTextWriter(this.Response.Output));
}
if (context.TraceIsEnabled)
{
this.Trace.Write("aspx.page", "End Render");
}
this.CheckRemainingAsyncTasks(false);
}
}
}
catch (ConfigurationException)
{
throw;
}

}

在这个方法中有两段代码比较有意思

this.OnInitComplete(EventArgs.Empty);

if (context.TraceIsEnabled)

{

this.Trace.Write("aspx.page", "End InitComplete");

}

if (this.IsPostBack)

{

if (context.TraceIsEnabled)

{

this.Trace.Write("aspx.page", "Begin LoadState");

}

this.LoadAllState();

if (context.TraceIsEnabled)

{

this.Trace.Write("aspx.page", "End LoadState");

this.Trace.Write("aspx.page", "Begin ProcessPostData");

}

this.ProcessPostData(this._requestValueCollection, true);

if (context.TraceIsEnabled)

{

this.Trace.Write("aspx.page", "End ProcessPostData");

}

}

if (context.TraceIsEnabled)

{

this.Trace.Write("aspx.page", "Begin PreLoad");

}

this.OnPreLoad(EventArgs.Empty);

和

this.LoadRecursive();

if (context.TraceIsEnabled)

{

this.Trace.Write("aspx.page", "End Load");

}

if (this.IsPostBack)

{

if (context.TraceIsEnabled)

{

this.Trace.Write("aspx.page", "Begin ProcessPostData Second Try");

}

this.ProcessPostData(this._leftoverPostData, false);

if (context.TraceIsEnabled)

{

this.Trace.Write("aspx.page", "End ProcessPostData Second Try");

this.Trace.Write("aspx.page", "Begin Raise ChangedEvents");

}

this.RaiseChangedEvents();

if (context.TraceIsEnabled)

{

this.Trace.Write("aspx.page", "End Raise ChangedEvents");

this.Trace.Write("aspx.page", "Begin Raise PostBackEvent");

}

this.RaisePostBackEvent(this._requestValueCollection);

if (context.TraceIsEnabled)

{

this.Trace.Write("aspx.page", "End Raise PostBackEvent");

}

}

if (context.TraceIsEnabled)

{

this.Trace.Write("aspx.page", "Begin
LoadComplete");

}

this.OnLoadComplete(EventArgs.Empty);

整过post过来的请求与get相比就多了这中间一点处理，我们也知道page在处理post请求时需要处理数据的加载IPostBackDataHandler和事件的触发IPostBackEventHandler.

所以为什么这回分成两段就比较好理解了。

有关他们的介绍如下：