一、Page本质是一个Control
我们首先要澄清的第一个概念是页面类Page本质是一个控件类，它派生于TemplateControl类，而TemplateControl派生自Control类。既然饭我没有乱吃，自然话也不会乱讲。借田有良老师的翠花给大家上证据如下：
二、Control的“生死之序”
- 1.实例化（Instantiate） 我们写控件一般不要接触此活动。
- 2.初始化（Initialize） 【初始化自己，创建它的子控件（但该过程控件的状态没有加载）。触发该控件的OnInit()事件。】我们写控件一般不要接触此活动。 【跟踪视图状态（Tracking View State）* 】这个比较重要，涉及到视图状态，一般情况下不必重载此方法。
- 3.加载视图状态（Load view state） * 只会在回传过程中调用此方法，用法同上。
- 4.加载回发数据（Load postback data）* 如果你的控件生成之后要和客户端交互，那么这个方法就很重要，只会在回传过程中调用此方法。
- 5.加载（Load） 这个活动一般只是Page的OnLoad才会要去管它，我们写控件一般不要接触此方法。
- 6.更改通知（Raise changed events）* 控件生成后，数据被客户端更改过，和加载回传数据是一路的。
- 7.处理回发事件（Raise postback event）* 一般用于实现IPostBackEventHandler接口的控件的把客户端事件转化成服务器端事件。只用于回传过程。
- 8.预呈现（PerRender）** 生成前期工作，这个是很重要的一个过程，通过重载OnPreRender方法实现自定义。
- 9.保存视图状态（Save view state）* 如果所以信息都是用ViewState[xxx]这种方式来保存，不必重载，只有自定义视图状态管理时才重载此方法，当然，这里做了手脚，LoadViewState也就一定要和这里的Save方法配套。
- 10.呈现（Render）*** 这个是主角，控件成生什么东东基本就由这里管了。
- 11.卸载（Unload）
- 12.释放（Dispose）
三、控件树的“合成模式（Composite）”
从设计模式的角度讲，页面模型是一个“合成模式（Composite）”，它本身是一棵由多层控件组成的结构树，顶层是Page，以下有叶有树枝，叶是不再包涵子控件的控件，枝是又包涵子控件的控件，每一层控件的"初始化\加载视图状态\加载\预呈现\保存视图状态\卸载"等方法都会调用子控件的对应方法，父控件调用子控件的方法，子又调用孙的，如此递归。
1、初始化：
internal virtual void InitRecursive(Control namingContainer)
{ this.ResolveAdapter();
if (this._controls != null)
{ if (this.flags[128])
{ namingContainer = this;
}
string collectionReadOnly = this._controls.SetCollectionReadOnly("Parent_collections_readonly"); int count = this._controls.Count;
for (int i = 0; i < count; i++)
{ Control control = this._controls[i];
control.UpdateNamingContainer(namingContainer);
if (control._id == null && namingContainer != null && !control.flags[64])
{ control.GenerateAutomaticID();
}
control._page = this.Page;
control.InitRecursive(namingContainer);
}
this._controls.SetCollectionReadOnly(collectionReadOnly);
}
if (this._controlState < ControlState.Initialized)
{ this._controlState = ControlState.ChildrenInitialized;
if (this.Page != null && !this.DesignMode && this.Page.ContainsTheme && this.EnableTheming)
{ this.ApplySkin(this.Page);
}
if (this.AdapterInternal != null)
{ this.AdapterInternal.OnInit(EventArgs.Empty);
}
else
{ this.OnInit(EventArgs.Empty);
}
this._controlState = ControlState.Initialized;
}
this.TrackViewState();
}
2、加载视图状态:
internal void LoadViewStateRecursive(object savedState)
{ if (savedState == null || this.flags[4])
{ return;
}
if (this.Page != null && this.Page.IsPostBack)
{ object obj = null;
Pair pair = savedState as Pair;
object first;
ArrayList arrayList;
if (pair != null)
{ first = pair.First;
arrayList = (ArrayList)pair.Second;
}
else
{ Triplet triplet = (Triplet)savedState;
first = triplet.First;
obj = triplet.Second;
arrayList = (ArrayList)triplet.Third;
}
try
{ if (obj != null && this.AdapterInternal != null)
{ this.AdapterInternal.LoadAdapterViewState(obj);
}
if (first != null)
{ this.LoadViewState(first);
}
if (arrayList != null)
{ if (this.LoadViewStateByID)
{ this.LoadChildViewStateByID(arrayList);
}
else
{ this.LoadChildViewStateByIndex(arrayList);
}
}
}
catch (InvalidCastException)
{ throw new HttpException(SR.GetString("Controls_Cant_Change_Between_Posts")); }
catch (IndexOutOfRangeException)
{ throw new HttpException(SR.GetString("Controls_Cant_Change_Between_Posts")); }
}
this._controlState = ControlState.ViewStateLoaded;
}
internal void LoadChildViewStateByID(ArrayList childState)
{ int count = childState.Count;
for (int i = 0; i < count; i += 2)
{ string text = (string)childState[i];
object obj = childState[i + 1];
Control control = this.FindControl(text);
if (control != null)
{ control.LoadViewStateRecursive(obj);
}
else
{ this.EnsureOccasionalFields();
if (this._occasionalFields.ControlsViewState == null)
{ this._occasionalFields.ControlsViewState = new Hashtable();
}
this._occasionalFields.ControlsViewState[text] = obj;
}
}
}
3、加载:
internal virtual void LoadRecursive()
{ if (this._controlState < ControlState.Loaded)
{ if (this.AdapterInternal != null)
{ this.AdapterInternal.OnLoad(EventArgs.Empty);
}
else
{ this.OnLoad(EventArgs.Empty);
}
}
if (this._controls != null)
{ string collectionReadOnly = this._controls.SetCollectionReadOnly("Parent_collections_readonly"); int count = this._controls.Count;
for (int i = 0; i < count; i++)
{ this._controls[i].LoadRecursive();
}
this._controls.SetCollectionReadOnly(collectionReadOnly);
}
if (this._controlState < ControlState.Loaded)
{ this._controlState = ControlState.Loaded;
}
}
4、预呈现:
internal virtual void PreRenderRecursiveInternal()
{ if (!this.Visible)
{ this.flags.Set(16);
}
else
{ this.flags.Clear(16);
this.EnsureChildControls();
if (this.AdapterInternal != null)
{ this.AdapterInternal.OnPreRender(EventArgs.Empty);
}
else
{ this.OnPreRender(EventArgs.Empty);
}
if (this._controls != null)
{ string collectionReadOnly = this._controls.SetCollectionReadOnly("Parent_collections_readonly"); int count = this._controls.Count;
for (int i = 0; i < count; i++)
{ this._controls[i].PreRenderRecursiveInternal();
}
this._controls.SetCollectionReadOnly(collectionReadOnly);
}
}
this._controlState = ControlState.PreRendered;
}
5、保存视图状态:
internal object SaveViewStateRecursive(ViewStateMode inheritedMode)
{ if (this.flags[4])
{ return null;
}
bool flag;
if (this.flags[8388608])
{ if (this.flags[16777216])
{ flag = true;
inheritedMode = ViewStateMode.Enabled;
}
else
{ flag = false;
inheritedMode = ViewStateMode.Disabled;
}
}
else
{ flag = (inheritedMode == ViewStateMode.Enabled);
}
object obj = null;
object obj2 = null;
if (flag)
{ if (this.AdapterInternal != null)
{ obj = this.AdapterInternal.SaveAdapterViewState();
}
obj2 = this.SaveViewState();
}
ArrayList arrayList = null;
if (this.HasControls())
{ ControlCollection controls = this._controls;
int count = controls.Count;
bool loadViewStateByID = this.LoadViewStateByID;
for (int i = 0; i < count; i++)
{ Control control = controls[i];
object obj3 = control.SaveViewStateRecursive(inheritedMode);
if (obj3 != null)
{ if (arrayList == null)
{ arrayList = new ArrayList(count);
}
if (loadViewStateByID)
{ control.EnsureID();
arrayList.Add(control.ID);
}
else
{ arrayList.Add(i);
}
arrayList.Add(obj3);
}
}
}
if (this.AdapterInternal != null)
{ if (obj2 != null || obj != null || arrayList != null)
{ return new Triplet(obj2, obj, arrayList);
}
}
else
{ if (obj2 != null || arrayList != null)
{ return new Pair(obj2, arrayList);
}
}
return null;
}
6、卸载:
internal virtual void UnloadRecursive(bool dispose)
{ Page page = this.Page;
if (page != null && page.RequiresControlState(this))
{ page.UnregisterRequiresControlState(this);
this.RareFieldsEnsured.RequiredControlState = true;
}
if (this.flags[2097152])
{ this._id = null;
this.flags.Clear(2097152);
}
if (this._controls != null)
{ string collectionReadOnly = this._controls.SetCollectionReadOnly("Parent_collections_readonly"); int count = this._controls.Count;
for (int i = 0; i < count; i++)
{ this._controls[i].UnloadRecursive(dispose);
}
this._controls.SetCollectionReadOnly(collectionReadOnly);
}
if (this.AdapterInternal != null)
{ this.AdapterInternal.OnUnload(EventArgs.Empty);
}
else
{ this.OnUnload(EventArgs.Empty);
}
if (dispose)
{ this.Dispose();
}
if (this.IsReloadable)
{ this._controlState = ControlState.Constructed;
}
}