从源码看ASP.NET框架(一)-打造页面控件树

测试实例如下:

前台代码MyFirstWeb.aspx(没有服务器控件,即没有runat)

CodeBehind=”MyFirstWeb.aspx.cs”:表示代码后置类文件
Inherits=”SimpleWeb.MyfirstWeb”:表示该前台类继承于代码后置类文件中的哪个类
<%@ Page Language="C#" AutoEventWireup="true" CodeBehind="MyFirstWeb.aspx.cs" Inherits="SimpleWeb.MyFirstWeb" %>

<!DOCTYPE html>

<html xmlns="http://www.w3.org/1999/xhtml">
<head runat="server">
<meta http-equiv="Content-Type" content="text/html; charset=utf-8"/>
    <title></title>
</head>
<body>
    <!--获取前台页面的程序集位置-->
    <%=this.GetType().Assembly.Location %>
    <form id="form1">
    <div>
    <input type="text" name="txtName"/>
        <input type="submit" id="btnClick"/>
    </div>
    </form>
</body>
</html>

后台代码

using System;
using System.Collections.Generic;
using System.Linq;
using System.Web;
using System.Web.UI;
using System.Web.UI.WebControls;

namespace SimpleWeb
{
    public partial class MyFirstWeb : System.Web.UI.Page
    {
        protected void Page_Load(object sender, EventArgs e)
        {
            Response.Write("Page_Load方法的开始<br/>");
            Response.Write("Page_Load方法的结束<br/>");
        }
    }
}

一个前台页面文件,在第一次被访问时,会被编译成一个类

前台页面会被编译成前台页面类myfirstweb_aspx继承于后台页面类MyFirstWeb.cs

发现前台类实现了IRequesSessionState:要取出Session中值,需要改接口
又实现了IHttpHandler:因为后台类继承于Page,Page已经实现了该接口,此处只为方便阅读而已
public class myfirstweb_aspx : MyFirstWeb, IRequiresSessionState, IHttpHandler
{
    // Fields
    private static object __fileDependencies;
    private static bool __initialized;
    private static MethodInfo __PageInspector_BeginRenderTracingMethod;
    private static MethodInfo __PageInspector_EndRenderTracingMethod;
    private static MethodInfo __PageInspector_SetTraceDataMethod;

    // Methods
    static myfirstweb_aspx();
    [DebuggerNonUserCode]
    public myfirstweb_aspx();
    [DebuggerNonUserCode]
    private HtmlHead __BuildControl__control2();
    [DebuggerNonUserCode]
    private HtmlMeta __BuildControl__control3();
    [DebuggerNonUserCode]
    private HtmlTitle __BuildControl__control4();
    [DebuggerNonUserCode]
    private void __BuildControlTree(myfirstweb_aspx __ctrl);
    private void __PageInspector_BeginRenderTracing(object[] parameters);
    private void __PageInspector_EndRenderTracing(object[] parameters);
    private static MethodInfo __PageInspector_LoadHelper(string helperName);
    private void __PageInspector_SetTraceData(object[] parameters);
    private void __Render__control1(HtmlTextWriter __w, Control parameterContainer);
    [DebuggerNonUserCode]
    protected override void FrameworkInitialize();
    [DebuggerNonUserCode]
    public override int GetTypeHashCode();
    [DebuggerNonUserCode]
    public override void ProcessRequest(HttpContext context);

    // Properties
    protected HttpApplication ApplicationInstance { get; }
    protected DefaultProfile Profile { get; }
}

后台页面类MyFirstWeb.cs,如下

public class MyFirstWeb : Page
{
    // Fields
    protected HtmlForm form1;

    // Methods
    protected void Page_Load(object sender, EventArgs e)
    {
        base.Response.Write("Page_Load方法的开始<br/>");
        base.Response.Write("Page_Load方法的结束<br/>");
    }
}

-------------------------------------------------------------开始分析源码-----------------------------------------------------------------------------------

1.当在浏览框中输入Localhost:MyFirstWeb.aspx,按回车的时候,

在请求管道的第8个事件,创建了与请求名同名的页面类对象myfirstweb_aspx.cs,

然后将该页面类对象保存到HttpContext中的RemapHandler中。

接着在管道的第11个事件和12个事件之间,调用页面对象的PR方法,

因为前台页面类继承于后台类,而后台类有继承于Page类,所以实际调用的是Page类的PR方法。

private void ProcessRequest()
{
    Thread currentThread = Thread.CurrentThread;
    CultureInfo currentCulture = currentThread.CurrentCulture;
    CultureInfo currentUICulture = currentThread.CurrentUICulture;
    try
    {
        this.ProcessRequest(true, true);
    }
    finally
    {
        this.RestoreCultures(currentThread, currentCulture, currentUICulture);
    }
}

1.1继续调用它的重载函数的PR方法

this.FrameworkInitialize(); 表示调用当前对象的FI方法,当前对象就是前台页面类,那么我们就转到前台页面类的FI方法看看;
protected override void FrameworkInitialize(); 发现在前台页面类中,重写了其父类的FI方法
private void ProcessRequest(bool includeStagesBeforeAsyncPoint, bool includeStagesAfterAsyncPoint)
{
    if (includeStagesBeforeAsyncPoint)
    {
        this.FrameworkInitialize();
        base.ControlState = ControlState.FrameworkInitialized;
    }
    bool flag = this.Context.WorkerRequest is IIS7WorkerRequest;
    try
    {
        try
        {
            if (this.IsTransacted)
            {
                this.ProcessRequestTransacted();
            }
            else
            {
                this.ProcessRequestMain(includeStagesBeforeAsyncPoint, includeStagesAfterAsyncPoint);
            }
            if (includeStagesAfterAsyncPoint)
            {
                flag = false;
                this.ProcessRequestEndTrace();
            }
        }
        catch (ThreadAbortException)
        {
            try
            {
                if (flag)
                {
                    this.ProcessRequestEndTrace();
                }
            }
            catch
            {
            }
        }
        finally
        {
            if (includeStagesAfterAsyncPoint)
            {
                this.ProcessRequestCleanup();
            }
        }
    }
    catch
    {
        throw;
    }
}

2.FI方法,代码如下

this.__BuildControlTree(this); 将前台页面对象作为参数传入,开始创建控件树
[DebuggerNonUserCode]
protected override void FrameworkInitialize()
{
    base.FrameworkInitialize();
    this.__BuildControlTree(this);
    base.AddWrappedFileDependencies(__fileDependencies);
    base.Request.ValidateInput();
}

2.1.__BuildControlTree()代码如下

myfirstweb_aspx __ctrl:那么_ctrl就是前台页面类;
IParserAccessor __parser = __ctrl:将_ctrl转为接口类型,那么此时_parser就是前台页面类;
__parser.AddParsedSubObject(__ctrl1):将_ctrl1添加到前台页面类中。
                                            问题一:_ctrl1是什么类型?还有它被添加到前台页面类的哪个成员中?
[DebuggerNonUserCode]
private void __BuildControlTree(myfirstweb_aspx __ctrl)
{
    this.InitializeCulture();
    HtmlHead __ctrl1 = this.__BuildControl__control2();
    IParserAccessor __parser = __ctrl;
    __parser.AddParsedSubObject(__ctrl1);
    __ctrl.SetRenderMethodDelegate(new RenderMethod(this.__Render__control1));
}

2.1.1.__BuildControl__control2();代码如下

HtmlHead __ctrl = new HtmlHead("head"):创建一个head标签,并添加到前台页面类中;
HtmlMeta __ctrl1 = this.__BuildControl__control3():设置meta的属性,并添加到head中;
HtmlTitle __ctrl2 = this.__BuildControl__control4():设置标题,并返回标题,然后添加到前台页面对象中;
[DebuggerNonUserCode]
private HtmlHead __BuildControl__control2()
{
    HtmlHead __ctrl = new HtmlHead("head");
    HtmlMeta __ctrl1 = this.__BuildControl__control3();
    IParserAccessor __parser = __ctrl;
    __parser.AddParsedSubObject(__ctrl1);
    HtmlTitle __ctrl2 = this.__BuildControl__control4();
    __parser.AddParsedSubObject(__ctrl2);
    object[] CS$0$0001 = new object[5];
    CS$0$0001[0] = __ctrl;
    CS$0$0001[2] = 180;
    CS$0$0001[3] = 0x79;
    CS$0$0001[4] = false;
    this.__PageInspector_SetTraceData(CS$0$0001);
    return __ctrl;
}

2.1.2.SetRenderMethodDelegate(new RenderMethod());调用一个委托,RenderMethod代码如下

__w.Write:生成的代码写入了一个字符数组中(详情看超链接,文章后续会发布),当输出的时候,也是按写入时的顺序;
__w.Write(base.GetType().Assembly.Location):很熟悉,就是我们在前台中写的C#代码,照样写入到字符数组中;
parameterContainer.Controls[0].RenderControl(__w):在控件容器中找到第一个控件,然后调用它的RenderControl方法,
                                                                                                   在开始创建控件树时,发现第一个被添加到控件容器的是HTMLHead
RenderControl(__w):也是吧代码写到字符数组中,不信自己看看源码
private void __Render__control1(HtmlTextWriter __w, Control parameterContainer)
{
    this.__PageInspector_BeginRenderTracing(new object[] { __w, "/MyFirstWeb.aspx", 0x70, 0x44, true });
    __w.Write("\r\n\r\n<!DOCTYPE html>\r\n\r\n<html xmlns=\"http://www.w3.org/1999/xhtml\">\r\n");
    this.__PageInspector_EndRenderTracing(new object[] { __w });
    parameterContainer.Controls[0].RenderControl(__w);
    this.__PageInspector_BeginRenderTracing(new object[] { __w, "/MyFirstWeb.aspx", 0x12d, 0x27, true });
    __w.Write("\r\n<body>\r\n    <!--获取前台页面的程序集位置-->\r\n    ");
    this.__PageInspector_EndRenderTracing(new object[] { __w });
    this.__PageInspector_BeginRenderTracing(new object[] { __w, "/MyFirstWeb.aspx", 340, 0x26, false });
    __w.Write(base.GetType().Assembly.Location);
    this.__PageInspector_EndRenderTracing(new object[] { __w });
    this.__PageInspector_BeginRenderTracing(new object[] { __w, "/MyFirstWeb.aspx", 0x17a, 0xa7, true });
    __w.Write("\r\n    <form id=\"form1\" >\r\n    <div>\r\n    <input type=\"text\" name=\"txtName\"/>\r\n        <input type=\"submit\" id=\"btnClick\"/>\r\n    </div>\r\n    </form>\r\n</body>\r\n</html>\r\n");
    this.__PageInspector_EndRenderTracing(new object[] { __w });
}

---------------------------------------------------------------问题解答--------------------------------------------------------------------------------------

问题一:_ctrl1是什么类型?还有它被添加到前台页面类的哪个成员中?

_ctrl1是前台页面类型,那么前台页面又是什么类型

myfirstweb_aspx继承于MyFirstWeb;

MyFirstWeb继承于Page;

Page继承于TemplateControl;(那么也可以说Page类也是一个控件)

TemplateControl继承于Control;

Control中有个只读属性,类型是控件集合类型:public virtual ControlCollection Controls { get; }

那么一切问题都解决了,通过创建控件树,创建了一个个控件,同时将这些控件依次添加到前台页面的控件集合中,然后依次调用控件的RenderControl方法,将结果添加到字符数组中,然后将字符数组输出给HttpRuntime,然后传给iis,最后返回给浏览器,浏览器在根据接收到的结果,渲染界面,这就是我们最终看到的。

技术分享

源码如下,就是按照字符数组中先后添加的代码显示到界面。为什么Page_Load中的数据先输出,请看超链接,文章后续会发布

Page_Load方法的开始<br/>Page_Load方法的结束<br/>

<!DOCTYPE html>

<html xmlns="http://www.w3.org/1999/xhtml">
<head><meta http-equiv="Content-Type" content="text/html; charset=utf-8" /><title>

</title></head>
<body>
    <!--获取前台页面的程序集位置-->
    D:\Users\Kimisme\AppData\Local\Temp\Temporary ASP.NET Files\root\5f14d39c\6593da16\App_Web_4br2rhb1.dll
    <form id="form1" >
    <div>
    <input type="text" name="txtName"/>
        <input type="submit" id="btnClick"/>
    </div>
    </form>

<!-- Visual Studio Browser Link -->
<script type="application/json" id="__browserLink_initializationData">
    {"appName":"InternetExplorer","requestId":"6cd255e00ebe439facbd972bb23ed352"}
</script>
<script type="text/javascript" src="http://localhost:1090/86ceaccf0cf9404491a3a03bf9ab677a/browserLink" async="async"></script>
<!-- End Browser Link -->

</body>
</html>

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