Xaml技术：浅析为什么说一个标签就是new一个对象？

在Xaml技术中，如WPF、Silverlight等，一个标签就是一个对象。很多人不理解为什么，现在我们就来一起研究一下吧！

首先，我们新建一个WPF应用程序，并在窗口中添加一个按钮：

<Window x:Class="WpfApplication1.MainWindow"
xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
Title="MainWindow" Height="350" Width="525">
<Grid>
<span style="color:#ff0000;"><strong><Button Name="btnHaHa" Content="哈哈" Foreground="Red" Margin="118,64,127,141"></Button></strong></span>
</Grid>
</Window>

调试运行后，打开文件夹...\WpfApplication1\obj\x86\Debug，我们会发现MainWindow.g.cs和MainWindow.g.i.cs两个文件，这是干什么的呢？我们打开看看：

#################################<strong><span style="color:#ff0000;">MainWindow.g.cs</span></strong>#############################################

#pragma checksum "..\..\..\MainWindow.xaml" "{406ea660-64cf-4c82-b6f0-42d48172a799}" "93AC7AD7A7AD9977990F9BD74B70C70D"
//------------------------------------------------------------------------------
// <auto-generated>
//     此代码由工具生成。
//     运行时版本:4.0.30319.18444
//
//     对此文件的更改可能会导致不正确的行为，并且如果
//     重新生成代码，这些更改将会丢失。
// </auto-generated>
//------------------------------------------------------------------------------

using System;
using System.Diagnostics;
using System.Windows;
using System.Windows.Automation;
using System.Windows.Controls;
using System.Windows.Controls.Primitives;
using System.Windows.Data;
using System.Windows.Documents;
using System.Windows.Ink;
using System.Windows.Input;
using System.Windows.Markup;
using System.Windows.Media;
using System.Windows.Media.Animation;
using System.Windows.Media.Effects;
using System.Windows.Media.Imaging;
using System.Windows.Media.Media3D;
using System.Windows.Media.TextFormatting;
using System.Windows.Navigation;
using System.Windows.Shapes;
using System.Windows.Shell;

namespace WpfApplication1 {

/// <summary>
/// MainWindow
/// </summary>
public partial class MainWindow : System.Windows.Window, System.Windows.Markup.IComponentConnector {

#line 6 "..\..\..\MainWindow.xaml"
[System.Diagnostics.CodeAnalysis.SuppressMessageAttribute("Microsoft.Performance", "CA1823:AvoidUnusedPrivateFields")]
<span style="color:#ff0000;"><strong>internal System.Windows.Controls.Button btnHaHa;</strong></span>

#line default
#line hidden

private bool _contentLoaded;

/// <summary>
/// InitializeComponent
/// </summary>
[System.Diagnostics.DebuggerNonUserCodeAttribute()]
[System.CodeDom.Compiler.GeneratedCodeAttribute("PresentationBuildTasks", "4.0.0.0")]
public void <span style="color:#000066;"><strong>InitializeComponent</strong></span>() {
if (_contentLoaded) {
return;
}
_contentLoaded = true;
System.Uri resourceLocater = new System.Uri("/WpfApplication1;component/mainwindow.xaml", System.UriKind.Relative);

#line 1 "..\..\..\MainWindow.xaml"
System.Windows.Application.LoadComponent(this, resourceLocater);

#line default
#line hidden
}

[System.Diagnostics.DebuggerNonUserCodeAttribute()]
[System.CodeDom.Compiler.GeneratedCodeAttribute("PresentationBuildTasks", "4.0.0.0")]
[System.ComponentModel.EditorBrowsableAttribute(System.ComponentModel.EditorBrowsableState.Never)]
[System.Diagnostics.CodeAnalysis.SuppressMessageAttribute("Microsoft.Design", "CA1033:InterfaceMethodsShouldBeCallableByChildTypes")]
[System.Diagnostics.CodeAnalysis.SuppressMessageAttribute("Microsoft.Maintainability", "CA1502:AvoidExcessiveComplexity")]
[System.Diagnostics.CodeAnalysis.SuppressMessageAttribute("Microsoft.Performance", "CA1800:DoNotCastUnnecessarily")]
void System.Windows.Markup.IComponentConnector.Connect(int connectionId, object target) {
switch (connectionId)
{
case 1:
<span style="color:#ff0000;background-color: rgb(255, 255, 255);"><strong>this.btnHaHa = ((System.Windows.Controls.Button)(target));</strong></span>
return;
}
this._contentLoaded = true;
}
}
}

<pre name="code" class="csharp">#################################<strong><span style="color: rgb(255, 0, 0);">MainWindow.g.i.cs</span></strong>#############################################

#pragma checksum "..\..\..\MainWindow.xaml" "{406ea660-64cf-4c82-b6f0-42d48172a799}" "93AC7AD7A7AD9977990F9BD74B70C70D"
//------------------------------------------------------------------------------
// <auto-generated>
//     此代码由工具生成。
//     运行时版本:4.0.30319.18444
//
//     对此文件的更改可能会导致不正确的行为，并且如果
//     重新生成代码，这些更改将会丢失。
// </auto-generated>
//------------------------------------------------------------------------------

using System;
using System.Diagnostics;
using System.Windows;
using System.Windows.Automation;
using System.Windows.Controls;
using System.Windows.Controls.Primitives;
using System.Windows.Data;
using System.Windows.Documents;
using System.Windows.Ink;
using System.Windows.Input;
using System.Windows.Markup;
using System.Windows.Media;
using System.Windows.Media.Animation;
using System.Windows.Media.Effects;
using System.Windows.Media.Imaging;
using System.Windows.Media.Media3D;
using System.Windows.Media.TextFormatting;
using System.Windows.Navigation;
using System.Windows.Shapes;
using System.Windows.Shell;

namespace WpfApplication1 {

/// <summary>
/// MainWindow
/// </summary>
public partial class MainWindow : System.Windows.Window, System.Windows.Markup.IComponentConnector {

#line 6 "..\..\..\MainWindow.xaml"
[System.Diagnostics.CodeAnalysis.SuppressMessageAttribute("Microsoft.Performance", "CA1823:AvoidUnusedPrivateFields")]
<strong><span style="color:#ff0000;">internal System.Windows.Controls.Button btnHaHa;</span></strong>

#line default
#line hidden

private bool _contentLoaded;

/// <summary>
/// InitializeComponent
/// </summary>
[System.Diagnostics.DebuggerNonUserCodeAttribute()]
[System.CodeDom.Compiler.GeneratedCodeAttribute("PresentationBuildTasks", "4.0.0.0")]
public void <span style="color:#000066;"><strong>InitializeComponent</strong></span>() {
if (_contentLoaded) {
return;
}
_contentLoaded = true;
System.Uri resourceLocater = new System.Uri("/WpfApplication1;component/mainwindow.xaml", System.UriKind.Relative);

#line 1 "..\..\..\MainWindow.xaml"
System.Windows.Application.LoadComponent(this, resourceLocater);

#line default
#line hidden
}

[System.Diagnostics.DebuggerNonUserCodeAttribute()]
[System.CodeDom.Compiler.GeneratedCodeAttribute("PresentationBuildTasks", "4.0.0.0")]
[System.ComponentModel.EditorBrowsableAttribute(System.ComponentModel.EditorBrowsableState.Never)]
[System.Diagnostics.CodeAnalysis.SuppressMessageAttribute("Microsoft.Design", "CA1033:InterfaceMethodsShouldBeCallableByChildTypes")]
[System.Diagnostics.CodeAnalysis.SuppressMessageAttribute("Microsoft.Maintainability", "CA1502:AvoidExcessiveComplexity")]
[System.Diagnostics.CodeAnalysis.SuppressMessageAttribute("Microsoft.Performance", "CA1800:DoNotCastUnnecessarily")]
void System.Windows.Markup.IComponentConnector.Connect(int connectionId, object target) {
switch (connectionId)
{
case 1:
<strong><span style="color:#ff0000;">this.btnHaHa = ((System.Windows.Controls.Button)(target));</span></strong>
return;
}
this._contentLoaded = true;
}
}
}

我们看到了什么？是不是很熟悉了，是不是和Winform中的窗体设计文件很类似呀！

注意：添加的控件需要唯一ID，也就是Name属性，否则在这两个文件中将找不到该对象的定义与初始化