DetailsView运行机制之研究

先从OnItemUpdating和OnItemUpdated事件开始:

        protected virtual void OnItemUpdating(DetailsViewUpdateEventArgs e)
        {
            bool flag1 = base.IsBoundUsingDataSourceID;
            DetailsViewUpdateEventHandler handler1 = (DetailsViewUpdateEventHandler) base.Events[DetailsView.EventItemUpdating];
            if (handler1 != null)
            {
                handler1(this, e);
            }
            else if (!flag1 && !e.Cancel)
            {
                throw new HttpException(System.Web.SR.GetString("DetailsView_UnhandledEvent", new object[] { this.ID, "ItemUpdating" }));
            }
        }

        protected virtual void OnItemUpdated(DetailsViewUpdatedEventArgs e)
        {
            DetailsViewUpdatedEventHandler handler1 = (DetailsViewUpdatedEventHandler) base.Events[DetailsView.EventItemUpdated];
            if (handler1 != null)
            {
                handler1(this, e);
            }
        }

从这两个方法中看不出什么，只是一个简单的事件触发函数。下面看看它们被调用的地方：
1.  OnItemUpdating方法被HandleUpdate方法调用：

        private void HandleUpdate(string commandArg, bool causesValidation)
        {
            if ((!causesValidation || (this.Page == null)) || this.Page.IsValid)
            {
                if (this.Mode != DetailsViewMode.Edit)
                {
                    throw new HttpException(System.Web.SR.GetString("DetailsViewFormView_ControlMustBeInEditMode", new object[] { "DetailsView", this.ID }));
                }
                if (this.PageIndex >= 0)
                {
                    DataSourceView view1 = null;
                    bool flag1 = base.IsBoundUsingDataSourceID;
                    if (flag1)
                    {
                        view1 = this.GetData();
                        if (view1 == null)
                        {
                            throw new HttpException(System.Web.SR.GetString("View_DataSourceReturnedNullView", new object[] { this.ID }));
                        }
                    }
                    DetailsViewUpdateEventArgs args1 = new DetailsViewUpdateEventArgs(commandArg);
                    if (flag1)
                    {
                        foreach (DictionaryEntry entry1 in this.BoundFieldValues)
                        {
                            args1.OldValues.Add(entry1.Key, entry1.Value);
                        }
                        this.ExtractRowValues(args1.NewValues, false, true);
                        foreach (DictionaryEntry entry2 in this.DataKey.Values)
                        {
                            args1.Keys.Add(entry2.Key, entry2.Value);
                        }
                    }
                    this.OnItemUpdating(args1);
                    if (!args1.Cancel && flag1)
                    {
                        this._updateKeys = args1.Keys;
                        this._updateNewValues = args1.NewValues;
                        this._updateOldValues = args1.OldValues;
                        view1.Update(args1.Keys, args1.NewValues, args1.OldValues, new DataSourceViewOperationCallback(this.HandleUpdateCallback));
                    }
                }
            }
        }

2. OnItemUpdated方法被HandleUpdateCallback调用

        private bool HandleUpdateCallback(int affectedRows, Exception ex)
        {
            DetailsViewUpdatedEventArgs args1 = new DetailsViewUpdatedEventArgs(affectedRows, ex);
            args1.SetOldValues(this._updateOldValues);
            args1.SetNewValues(this._updateNewValues);
            args1.SetKeys(this._updateKeys);
            this.OnItemUpdated(args1);
            this._updateKeys = null;
            this._updateOldValues = null;
            this._updateNewValues = null;
            if ((ex != null) && !args1.ExceptionHandled)
            {
                return false;
            }
            if (!args1.KeepInEditMode)
            {
                DetailsViewModeEventArgs args2 = new DetailsViewModeEventArgs(this.DefaultMode, false);
                this.OnModeChanging(args2);
                if (!args2.Cancel)
                {
                    this.Mode = args2.NewMode;
                    this.OnModeChanged(EventArgs.Empty);
                    base.RequiresDataBinding = true;
                }
            }
            return true;
        }

下面看看HandleUpdate，HandleUpdateCallback这两个方法被调用的地方:

1. HandleUpdate方法被调用的地方

        private bool HandleEvent(EventArgs e, bool causesValidation, string validationGroup)
        {
            bool flag1 = false;
            if (causesValidation && (this.Page != null))
            {
                this.Page.Validate(validationGroup);
            }
            DetailsViewCommandEventArgs args1 = e as DetailsViewCommandEventArgs;
            if (args1 != null)
            {
                this.OnItemCommand(args1);
                flag1 = true;
                string text1 = args1.CommandName;
                int num1 = this.PageIndex;
                if (StringUtil.EqualsIgnoreCase(text1, "Page"))
                {
                    string text2 = (string) args1.CommandArgument;
                    if (StringUtil.EqualsIgnoreCase(text2, "Next"))
                    {
                        num1++;
                    }
                    else if (StringUtil.EqualsIgnoreCase(text2, "Prev"))
                    {
                        num1--;
                    }
                    else if (StringUtil.EqualsIgnoreCase(text2, "First"))
                    {
                        num1 = 0;
                    }
                    else if (StringUtil.EqualsIgnoreCase(text2, "Last"))
                    {
                        if (base.IsViewStateEnabled)
                        {
                            num1 = this.PageCount - 1;
                        }
                        else
                        {
                            num1 = 0x7fffffff;
                        }
                    }
                    else
                    {
                        num1 = Convert.ToInt32(text2, CultureInfo.InvariantCulture) - 1;
                    }
                    this.HandlePage(num1);
                    return flag1;
                }
                if (StringUtil.EqualsIgnoreCase(text1, "Edit"))
                {
                    this.HandleEdit();
                    return flag1;
                }
                if (StringUtil.EqualsIgnoreCase(text1, "Update"))
                {
                    this.HandleUpdate((string) args1.CommandArgument, causesValidation);
                    return flag1;
                }
                if (StringUtil.EqualsIgnoreCase(text1, "Cancel"))
                {
                    this.HandleCancel();
                    return flag1;
                }
                if (StringUtil.EqualsIgnoreCase(text1, "Delete"))
                {
                    this.HandleDelete((string) args1.CommandArgument);
                    return flag1;
                }
                if (StringUtil.EqualsIgnoreCase(text1, "Insert"))
                {
                    this.HandleInsert((string) args1.CommandArgument, causesValidation);
                    return flag1;
                }
                if (StringUtil.EqualsIgnoreCase(text1, "New"))
                {
                    this.HandleNew();
                }
            }
            return flag1;
        }

        public virtual void UpdateItem(bool causesValidation)
        {
            this.HandleUpdate(string.Empty, causesValidation);
        }

2. HandleUpdateCallback方法被调用的地方

        private void HandleUpdate(string commandArg, bool causesValidation)
        {
            if ((!causesValidation || (this.Page == null)) || this.Page.IsValid)
            {
                if (this.Mode != DetailsViewMode.Edit)
                {
                    throw new HttpException(System.Web.SR.GetString("DetailsViewFormView_ControlMustBeInEditMode", new object[] { "DetailsView", this.ID }));
                }
                if (this.PageIndex >= 0)
                {
                    DataSourceView view1 = null;
                    bool flag1 = base.IsBoundUsingDataSourceID;
                    if (flag1)
                    {
                        view1 = this.GetData();
                        if (view1 == null)
                        {
                            throw new HttpException(System.Web.SR.GetString("View_DataSourceReturnedNullView", new object[] { this.ID }));
                        }
                    }
                    DetailsViewUpdateEventArgs args1 = new DetailsViewUpdateEventArgs(commandArg);
                    if (flag1)
                    {
                        foreach (DictionaryEntry entry1 in this.BoundFieldValues)
                        {
                            args1.OldValues.Add(entry1.Key, entry1.Value);
                        }
                        this.ExtractRowValues(args1.NewValues, false, true);
                        foreach (DictionaryEntry entry2 in this.DataKey.Values)
                        {
                            args1.Keys.Add(entry2.Key, entry2.Value);
                        }
                    }
                    this.OnItemUpdating(args1);
                    if (!args1.Cancel && flag1)
                    {
                        this._updateKeys = args1.Keys;
                        this._updateNewValues = args1.NewValues;
                        this._updateOldValues = args1.OldValues;
                        view1.Update(args1.Keys, args1.NewValues, args1.OldValues, new DataSourceViewOperationCallback(this.HandleUpdateCallback));
                    }
                }
            }
        }

从上面可以看到:
          HandleUpdateCallback 被 HandleUpdate 方法调用。
          HandleUpdate 被 HandleEvent 和 UpdateItem 方法调用。
现在看一下 HandleEvent 和 UpdateItem  方法调用:
1. HandleEvent方法被调用的地方：

        protected override bool OnBubbleEvent(object source, EventArgs e)
        {
            bool flag1 = false;
            string text1 = string.Empty;
            DetailsViewCommandEventArgs args1 = e as DetailsViewCommandEventArgs;
            if (args1 != null)
            {
                IButtonControl control1 = args1.CommandSource as IButtonControl;
                if (control1 != null)
                {
                    flag1 = control1.CausesValidation;
                    text1 = control1.ValidationGroup;
                }
            }
            return this.HandleEvent(e, flag1, text1);
        }

        protected virtual void RaisePostBackEvent(string eventArgument)
        {
            base.ValidateEvent(this.UniqueID, eventArgument);
            int num1 = eventArgument.IndexOf('$');
            if (num1 >= 0)
            {
                CommandEventArgs args1 = new CommandEventArgs(eventArgument.Substring(0, num1), eventArgument.Substring(num1 + 1));
                DetailsViewCommandEventArgs args2 = new DetailsViewCommandEventArgs(this, args1);
                this.HandleEvent(args2, false, string.Empty);
            }
        }

2. UpdateItem  方法是个虚方法，未找到被调用的地方，不过可以直接调用DetailsView.UpdateItem()方法。

下面研究RaisePostBackEvent被调用的地方：

        void IPostBackEventHandler.RaisePostBackEvent(string eventArgument)
        {
            this.RaisePostBackEvent(eventArgument);
        }

这里的IPostBackEventHandler是DetailsView继承的接口之一。

最后集中研究OnBubbleEvent和IPostBackEventHandler.RaisePostBackEvent方法被调用的地方，这里要涉及到页面的生命周期:

DetailsView.OnBubbleEvent 方法:

确定 Web 服务器控件的事件是否沿页的用户界面 (UI) 服务器控件层次结构向上传递。 

命名空间:System.Web.UI.WebControls
程序集:System.Web（在 system.web.dll 中）

语法
Visual Basic（声明） 
Protected Overrides Function OnBubbleEvent ( _
    source As Object, _
    e As EventArgs _
) As Boolean
 
Visual Basic（用法） 
Dim source As Object
Dim e As EventArgs
Dim returnValue As Boolean

returnValue = Me.OnBubbleEvent(source, e)
 
C# 
protected override bool OnBubbleEvent (
    Object source,
    EventArgs e
)
 
C++ 
protected:
virtual bool OnBubbleEvent (
    Object^ source, 
    EventArgs^ e
) override
 
J# 
protected boolean OnBubbleEvent (
    Object source, 
    EventArgs e
)
 
JScript 
protected override function OnBubbleEvent (
    source : Object, 
    e : EventArgs
) : boolean
 


参数
source
事件源。

e
包含事件数据的 EventArgs。



返回值
如果事件已被取消，则为 true；否则为 false。 
备注
OnBubbleEvent 方法实现了 Control.OnBubbleEvent 方法以将事件从子控件传递到页层次结构。

给继承者的说明 在派生类中重写 OnBubbleEvent 时，一定要调用基类的 OnBubbleEvent 方法，以便已注册的委托对事件进行接收

Control.OnBubbleEvent 方法:

确定服务器控件的事件是否沿页的 UI 服务器控件层次结构向上传递。 

命名空间:System.Web.UI
程序集:System.Web（在 system.web.dll 中）

语法
Visual Basic（声明） 
Protected Overridable Function OnBubbleEvent ( _
    source As Object, _
    args As EventArgs _
) As Boolean
 
Visual Basic（用法） 
Dim source As Object
Dim args As EventArgs
Dim returnValue As Boolean

returnValue = Me.OnBubbleEvent(source, args)
 
C# 
protected virtual bool OnBubbleEvent (
    Object source,
    EventArgs args
)
 
C++ 
protected:
virtual bool OnBubbleEvent (
    Object^ source, 
    EventArgs^ args
)
 
J# 
protected boolean OnBubbleEvent (
    Object source, 
    EventArgs args
)
 
JScript 
protected function OnBubbleEvent (
    source : Object, 
    args : EventArgs
) : boolean
 


参数
source
事件源。 

args
包含事件数据的 EventArgs 对象。 



返回值
如果事件已被取消，则为 true；否则为 false。默认为 false。 
备注
ASP.NET 服务器控件（如 Repeater、DataList 和 DataGrid Web 控件）可以包含引发事件的子控件。例如，DataGrid 控件中的每一行都可以包含一个或多个由模板动态创建的按钮。不是由每个按钮分别引发事件，而是嵌套控件中的事件“冒泡”，即它们被发送到命名容器。命名容器然后引发带参数值的名为 ItemCommand 的一般事件。这些值使您可以确定引发原始事件的单个控件。通过响应这一事件，可以不必为子控件分别编写事件处理方法。

示例
下面的示例重写自定义 ASP.NET 服务器控件 ParentControl 中的 OnBubbleEvent 方法。在 ParentControl 的子控件调用 RaiseBubbleEvent 方法时会调用此方法。当这种情况发生时，ParentControl 类将两个字符串写入包含 ASP.NET 的页中，第一个字符串说明其 OnBubbleEvent 方法已被调用，第二个字符串标识 RaiseBubbleEvent 方法的源控件。

Visual Basic  复制代码 
Public Class ParentControl
   Inherits Control
   
   <System.Security.Permissions.PermissionSetAttribute(System.Security.Permissions.SecurityAction.Demand, Name:="FullTrust")> _
   Protected Overrides Function OnBubbleEvent(sender As Object, e As EventArgs) As Boolean
      Context.Response.Write("<br><br>ParentControl's OnBubbleEvent called.")
      Context.Response.Write(("<br>Source of event is: " + sender.ToString()))
      Return True
   End Function 'OnBubbleEvent
   
   <System.Security.Permissions.PermissionSetAttribute(System.Security.Permissions.SecurityAction.Demand, Name:="FullTrust")> _
   Protected Overrides Sub Render(myWriter As HtmlTextWriter)
      myWriter.Write("ParentControl")
      RenderChildren(myWriter)
   End Sub 'Render
End Class 'ParentControl
 _

 
C#  复制代码 
public class ParentControl : Control 
{
   [System.Security.Permissions.PermissionSet(System.Security.Permissions.SecurityAction.Demand, Name="FullTrust")] 
   protected override bool OnBubbleEvent(object sender, EventArgs e)
   {
      Context.Response.Write("<br><br>ParentControl's OnBubbleEvent called.");
      Context.Response.Write("<br>Source of event is: " + sender.ToString());
      return true;
   }
   [System.Security.Permissions.PermissionSet(System.Security.Permissions.SecurityAction.Demand, Name="FullTrust")] 
   protected override void Render( HtmlTextWriter myWriter)
   {
      myWriter.Write("ParentControl");
      RenderChildren(myWriter);
   }
}

至此上述方法和事件之间的关系总结如下图：



下面来研究OnItemCommand方法：

        protected virtual void OnItemCommand(DetailsViewCommandEventArgs e)
        {
            DetailsViewCommandEventHandler handler1 = (DetailsViewCommandEventHandler) base.Events[DetailsView.EventItemCommand];
            if (handler1 != null)
            {
                handler1(this, e);
            }
        }

OnItemCommand方法被调用的地方：

        private bool HandleEvent(EventArgs e, bool causesValidation, string validationGroup)
        {
            bool flag1 = false;
            if (causesValidation && (this.Page != null))
            {
                this.Page.Validate(validationGroup);
            }
            DetailsViewCommandEventArgs args1 = e as DetailsViewCommandEventArgs;
            if (args1 != null)
            {
                this.OnItemCommand(args1);
                flag1 = true;
                string text1 = args1.CommandName;
                int num1 = this.PageIndex;
                if (StringUtil.EqualsIgnoreCase(text1, "Page"))
                {
                    string text2 = (string) args1.CommandArgument;
                    if (StringUtil.EqualsIgnoreCase(text2, "Next"))
                    {
                        num1++;
                    }
                    else if (StringUtil.EqualsIgnoreCase(text2, "Prev"))
                    {
                        num1--;
                    }
                    else if (StringUtil.EqualsIgnoreCase(text2, "First"))
                    {
                        num1 = 0;
                    }
                    else if (StringUtil.EqualsIgnoreCase(text2, "Last"))
                    {
                        if (base.IsViewStateEnabled)
                        {
                            num1 = this.PageCount - 1;
                        }
                        else
                        {
                            num1 = 0x7fffffff;
                        }
                    }
                    else
                    {
                        num1 = Convert.ToInt32(text2, CultureInfo.InvariantCulture) - 1;
                    }
                    this.HandlePage(num1);
                    return flag1;
                }
                if (StringUtil.EqualsIgnoreCase(text1, "Edit"))
                {
                    this.HandleEdit();
                    return flag1;
                }
                if (StringUtil.EqualsIgnoreCase(text1, "Update"))
                {
                    this.HandleUpdate((string) args1.CommandArgument, causesValidation);
                    return flag1;
                }
                if (StringUtil.EqualsIgnoreCase(text1, "Cancel"))
                {
                    this.HandleCancel();
                    return flag1;
                }
                if (StringUtil.EqualsIgnoreCase(text1, "Delete"))
                {
                    this.HandleDelete((string) args1.CommandArgument);
                    return flag1;
                }
                if (StringUtil.EqualsIgnoreCase(text1, "Insert"))
                {
                    this.HandleInsert((string) args1.CommandArgument, causesValidation);
                    return flag1;
                }
                if (StringUtil.EqualsIgnoreCase(text1, "New"))
                {
                    this.HandleNew();
                }
            }
            return flag1;
        }

也是在HandleEvent方法中被调用的。
但是在HandleEvent方法中，OnItemCommand在HandleUpdate方法之前，这就是说，OnItemCommand中的Update方法，在OnItemUpdating和OnItemUpdated方法之前。
    在这里将前面的图完善一下：


下面看一下DataSourceID中对应的UpdateMethod方法的运行原理：