Page对象在Init阶段递归调用其内部控件的TrackViewState()方法

我们知道，Page对象Init阶段，要调用Control.InitRecursive方法，这个方法的内部会递归调用其内部控件的TrackViewState()方法，我们先看看Control.InitRecursive方法的源码：

        internal virtual void InitRecursive(Control namingContainer) {
            ResolveAdapter();
            if (_occasionalFields != null && _occasionalFields.Controls != null) { 
                if (flags[isNamingContainer]) {
                    namingContainer = this; 
                } 
                string oldmsg = _occasionalFields.Controls.SetCollectionReadOnly(SR.Parent_collections_readonly);
 
                int controlCount = _occasionalFields.Controls.Count;
                for (int i = 0; i < controlCount; i++) {
                    Control control = _occasionalFields.Controls[i];
 
                    // Propagate the page and namingContainer
                    control.UpdateNamingContainer(namingContainer); 
 
                    if ((control._id == null) && (namingContainer != null) && !control.flags[idNotRequired]) {
                        control.GenerateAutomaticID(); 
                    }
                    control._page = Page;

                    control.InitRecursive(namingContainer); 
                }
                _occasionalFields.Controls.SetCollectionReadOnly(oldmsg); 
 
            }
 
            // Only make the actual call if it hasn't already happened (ASURT 111303)
            if (_controlState < ControlState.Initialized) {
                _controlState = ControlState.ChildrenInitialized; // framework also initialized
 
                if ((Page != null) && !DesignMode) {
                    if (Page.ContainsTheme && EnableTheming) { 
                        ApplySkin(Page); 
                    }
                } 

                if (_adapter != null) {
                    _adapter.OnInit(EventArgs.Empty);
                } 
                else {
                    OnInit(EventArgs.Empty); 
                } 

                _controlState = ControlState.Initialized; 
            }

            // track all subsequent state changes
            TrackViewState(); 

#if DEBUG 
            ControlInvariant(); 
#endif
        } 
Control.TrackViewState()方法源码：

        /// <devdoc>
        ///    <para>Turns on tracking of view state changes to the control 
        ///       so that they can be stored in the <see langword='StateBag'/>
        ///       object.</para> 
        /// </devdoc> 
        protected virtual void TrackViewState() {
            if (_viewState != null) 
                _viewState.TrackViewState();

            flags.Set(marked);
        } 

下边我用一个简单的示例，来表示一下这个过程：

 1Code
 2<%@ Page Language="C#" AutoEventWireup="true" CodeFile="Default.aspx.cs" Inherits="_Default" %>
 3
 4<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
 5<html xmlns="http://www.w3.org/1999/xhtml">
 6<head runat="server">
 7    <title>无标题页</title>
 8</head>
 9<body>
10    <form id="form1" runat="server">
11        <div>
12            <asp:Literal ID="Literal1" runat="server"></asp:Literal></div>
13    </form>
14</body>
15</html>

上边是一段简单的代码，下边用顺序图的方式来说明一下这段代码的主要对象(Page,HtmlForm,Literal)是如何递归调用子控件的TrackViewState（）方法：


 

posted @ 2008-04-14 13:28  王庆  阅读(526)  评论(0)    收藏  举报