区分Control类和WebControl类：
服务器控件可以继承自这两个类；
探究这个两个类的区别，以及这两个类分别适用在哪种情况！
本文的学习过程中，使用到的类库为ControlLibrary，这个类库可以自己命名；
首先编写一个继承自Control类的SimpleControl控件：类库中新建一个SimpleControl类
using System;
using System.Web;
using System.Web.UI;
namespace ControlLibrary
{ //继承Control类
public class SimpleControl:Control
{ //重载Render方法
protected override void Render(HtmlTextWriter writer)
{ //调用HtmlTextWriter的Write方法，向页面写入内容
writer.Write("This is my first Control");
}
}
}
再编写一个继承自WebControl类的SimpleWebControl；类库中新建一个SimpleWebControl类
具体代码：
using System;
using System.Web;
using System.Web.UI;
using System.Web.UI.WebControls;
namespace ControlLibrary
{
public class SimpleWebControl:WebControl
{
private int _number;
public int Number
{
get
{
return _number;
}
set
{
_number = value;
}
}
//默认标签为<span>
protected override HtmlTextWriterTag TagKey
{
get
{
return HtmlTextWriterTag.Div;
}
}
protected override void RenderContents(System.Web.UI.HtmlTextWriter writer)
{
writer.Write("This is my first WebControl");
writer.Write("<br>");
writer.Write("this WebControl property is Number");
writer.Write("<br>");
writer.Write("this Number is :");
writer.Write(Number);
}
}
}
页面中代码：
<%@ Page Language="C#" AutoEventWireup="true" CodeBehind="Default.aspx.cs" Inherits="WebSite.Default" %>
//服务器控件注册
<%@ Register TagPrefix="nsp" Namespace="ControlLibrary" Assembly="ControlLibrary" %>
<!DOCTYPE html>
<html xmlns="http://www.w3.org/1999/xhtml">
<head runat="server">
<meta http-equiv="Content-Type" content="text/html; charset=utf-8"/>
<link rel="stylesheet" href="Style/Site.css" type="text/css" />
<title></title>
</head>
<body>
<nsp:SimpleControl runat="server"/>
<br/>
<br/>
<nsp:SimpleWebControl runat="server"/>
</body>
</html>
通过这两个简单的控件（单标签），我们可以发现一些基础的区别：
继承自Control的控件：
通过重载Render来向Html响应流中写入内容；
无默认标签，直接写入页面中
不带有样式设计
继承自WebControl的控件：
通过重载RenderContents来向Html写入内容；
默认一个<span>标签，并将内容存放进入（重载HtmlTextWriterTag可以使用其他标签）
默认带有样式设计
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分别用继承自Control和WebControl，来编写一个复杂的控件（多标签）：
继承自Control，新建一个ComplexControl类：
using System;
using System.Web;
using System.Web.UI;
namespace ControlLibrary
{
public class ComplexControl:Control
{
private string _name;
public string Name
{
get
{
return _name;
}
set
{
_name = value;
}
}
//确定此控件没有子控件
protected override ControlCollection CreateControlCollection()
{
return new EmptyControlCollection(this);
}
protected override void Render(HtmlTextWriter writer)
{
writer.AddAttribute(HtmlTextWriterAttribute.Id,this.UniqueID);
writer.AddStyleAttribute(HtmlTextWriterStyle.BorderColor,"red");
writer.AddStyleAttribute(HtmlTextWriterStyle.BorderStyle,"solid");
writer.AddStyleAttribute(HtmlTextWriterStyle.BorderWidth, "1px");
writer.RenderBeginTag(HtmlTextWriterTag.Table);
writer.RenderBeginTag(HtmlTextWriterTag.Tr);
writer.RenderBeginTag(HtmlTextWriterTag.Td);
writer.Write("请输入用户名");
writer.RenderEndTag();//td
writer.RenderBeginTag(HtmlTextWriterTag.Td);
writer.AddAttribute(HtmlTextWriterAttribute.Name,"Username");
writer.RenderBeginTag(HtmlTextWriterTag.Input);
writer.RenderEndTag();//input
writer.RenderEndTag();//td
writer.RenderEndTag();//tr
writer.RenderBeginTag(HtmlTextWriterTag.Tr);
writer.RenderBeginTag(HtmlTextWriterTag.Td);
writer.Write("请输入密码");
writer.RenderEndTag();//td
writer.RenderBeginTag(HtmlTextWriterTag.Td);
writer.AddAttribute(HtmlTextWriterAttribute.Name, "Password");
writer.RenderBeginTag(HtmlTextWriterTag.Input);
writer.RenderEndTag();//input
writer.RenderEndTag();//td
writer.RenderEndTag();//tr
writer.RenderBeginTag(HtmlTextWriterTag.Tr);
writer.RenderBeginTag(HtmlTextWriterTag.Td);
writer.AddAttribute(HtmlTextWriterAttribute.Type,"button");
writer.AddAttribute(HtmlTextWriterAttribute.Value,"登录");
writer.RenderBeginTag(HtmlTextWriterTag.Input);
writer.RenderEndTag();//input
writer.RenderEndTag();//td
writer.RenderEndTag();//tr
writer.RenderEndTag();//table
}
}
}