研究RenderControl,Render,RenderChildren的执行顺序

我们主要研究RenderControl,Render,RenderChildren的执行顺序.
三者的含义从他们的命名可以很清楚的看出.
RenderControl绘制控件
Render绘制
RenderChildren绘制子控件
看下面的代码
public class UserComponent : Control
{
     public UserComponent()
     {
     }

     public override void RenderControl(HtmlTextWriter writer)
     {
         writer.Write(@"<script language='javascript'>alert('RenderControl');</script>");
         //base.RenderControl(writer);
     }

     protected override void Render(HtmlTextWriter writer)
     {
         writer.Write(@"<script language='javascript'>alert('Render');</script>");
         //base.Render(writer);
     }

     protected override void RenderChildren(HtmlTextWriter writer)
     {
          writer.Write(@"<script language='javascript'>alert('RenderChildren');</script>");
          //base.RenderChildren(writer);
     }
}
运行程序:只弹出对话框 RenderControl
说明:最先被调用的是 RenderControl 绘制控件

将base.RenderControl(writer);的注释去掉
public override void RenderControl(HtmlTextWriter writer)
{
    writer.Write(@"<script language='javascript'>alert('RenderControl');</script>");
    base.RenderControl(writer);
}
运行程序:弹出对话框 RenderControl 然后弹出对话框 Render
说明:控件通过 RenderControl 调用了 Redner

将base.Render(writer);的注释去掉
protected override void Render(HtmlTextWriter writer)
{
         writer.Write(@"<script language='javascript'>alert('Render');</script>");
         base.Render(writer);
}
运行程序:弹出对话框 RenderControl 然后弹出对话框 Render 然后弹出对话框 RenderChildren
说明:控件通过 RenderControl 调用了 Redner 调用 RenderChildren

现在来看下面的代码,应该有些感觉了吧...

(DesignerSerializationVisibility.Hidden)]，AddAttributesToRender方法
using System;
using System.Web.UI;

namespace WebComponent
{
    public class UserComponent : Control
    {
                   
        public UserComponent()
        {
         }

        public override void RenderControl(HtmlTextWriter writer)
        {
            //writer.Write(@"<script language='javascript'>alert('RenderControl');</script>");
            //base.RenderControl(writer);
           
            if (this.Visible)
            {
                 Render(writer);
             }
               
         }

        protected override void Render(HtmlTextWriter writer)
        {
            //writer.Write(@"<script language='javascript'>alert('Render');</script>");
            //base.Render(writer);
         
             RenderChildren(writer);

           
          }

        protected override void RenderChildren(HtmlTextWriter writer)
        {
            //writer.Write(@"<script language='javascript'>alert('RenderChildren');</script>");
            //base.RenderChildren(writer);

            foreach (Control c in this.Controls)
            {
                 c.RenderControl(writer);
             }

         }
   
     }
}
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