构建自定义控件时，需要考虑周全状态管理。
是用ViewState来管理状态
能够保存在ViewState里边的包括一些标准结合类和带有Serializable 标记的类。
下面自定义控件，实现了用viewstate来保存变量。从而显示到客户端
代码
using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Web;
using System.Web.UI;
using System.Web.UI.WebControls;
using System.Collections;
namespace OwnControl
{
public class BarGrphaControl:Control
{
private ArrayList dataDescription;
private ArrayList dataValues;
private double max;
public BarGrphaControl()
{
dataDescription = new ArrayList();
dataValues = new ArrayList();
}
public void AddValue(string name, double value)
{
dataDescription.Add(name);
dataValues.Add(value);
if (value > max)
max = value;
}
protected override void Render(HtmlTextWriter writer)
{
writer.AddAttribute(HtmlTextWriterAttribute.Border, "5px");
writer.RenderBeginTag(HtmlTextWriterTag.Table);
foreach (object objStr in dataDescription)
{
writer.AddAttribute(HtmlTextWriterAttribute.Border, "5px");
writer.RenderBeginTag(HtmlTextWriterTag.Tr);
foreach (object objValue in dataValues)
{
writer.AddAttribute(HtmlTextWriterAttribute.Border, "5px");
writer.RenderBeginTag(HtmlTextWriterTag.Td);
writer.Write(objStr);
writer.RenderEndTag();
writer.AddAttribute(HtmlTextWriterAttribute.Border, "5px");
writer.AddAttribute(HtmlTextWriterAttribute.Style, "background-color:Red");
string widthValue=string.Format("{0}px",objValue.ToString());
writer.AddAttribute(HtmlTextWriterAttribute.Width, widthValue);
writer.RenderBeginTag(HtmlTextWriterTag.Td);
writer.RenderEndTag();
}
writer.RenderEndTag();
}
writer.RenderEndTag();
}
protected override void LoadViewState(object savedState)
{
if (savedState != null)
{
object[] objStae = (object[])savedState;
if (objStae[0] != null)
base.LoadViewState(objStae[0]);
if (objStae[1] != null)
dataDescription = (ArrayList)objStae[1];
if (objStae[2] != null)
dataValues = (ArrayList)objStae[2];
if (objStae[3] != null)
max = (double)objStae[3];
}
}
protected override object SaveViewState()
{
object[] objRet = new object[4];
objRet[0] = base.SaveViewState();
objRet[1] = dataDescription;
objRet[2] = dataValues;
objRet[3] = max;
return objRet;
}
}
}
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Web;
using System.Web.UI;
using System.Web.UI.WebControls;
using System.Collections;
namespace OwnControl
{
public class BarGrphaControl:Control
{
private ArrayList dataDescription;
private ArrayList dataValues;
private double max;
public BarGrphaControl()
{
dataDescription = new ArrayList();
dataValues = new ArrayList();
}
public void AddValue(string name, double value)
{
dataDescription.Add(name);
dataValues.Add(value);
if (value > max)
max = value;
}
protected override void Render(HtmlTextWriter writer)
{
writer.AddAttribute(HtmlTextWriterAttribute.Border, "5px");
writer.RenderBeginTag(HtmlTextWriterTag.Table);
foreach (object objStr in dataDescription)
{
writer.AddAttribute(HtmlTextWriterAttribute.Border, "5px");
writer.RenderBeginTag(HtmlTextWriterTag.Tr);
foreach (object objValue in dataValues)
{
writer.AddAttribute(HtmlTextWriterAttribute.Border, "5px");
writer.RenderBeginTag(HtmlTextWriterTag.Td);
writer.Write(objStr);
writer.RenderEndTag();
writer.AddAttribute(HtmlTextWriterAttribute.Border, "5px");
writer.AddAttribute(HtmlTextWriterAttribute.Style, "background-color:Red");
string widthValue=string.Format("{0}px",objValue.ToString());
writer.AddAttribute(HtmlTextWriterAttribute.Width, widthValue);
writer.RenderBeginTag(HtmlTextWriterTag.Td);
writer.RenderEndTag();
}
writer.RenderEndTag();
}
writer.RenderEndTag();
}
protected override void LoadViewState(object savedState)
{
if (savedState != null)
{
object[] objStae = (object[])savedState;
if (objStae[0] != null)
base.LoadViewState(objStae[0]);
if (objStae[1] != null)
dataDescription = (ArrayList)objStae[1];
if (objStae[2] != null)
dataValues = (ArrayList)objStae[2];
if (objStae[3] != null)
max = (double)objStae[3];
}
}
protected override object SaveViewState()
{
object[] objRet = new object[4];
objRet[0] = base.SaveViewState();
objRet[1] = dataDescription;
objRet[2] = dataValues;
objRet[3] = max;
return objRet;
}
}
}
界面程序：
<%@ Page Language="C#" AutoEventWireup="true" CodeBehind="TestStateViewForm.aspx.cs" Inherits="TestCodeBehind.TestStateViewForm" %>
<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
<%@ Register Namespace="OwnControl" TagPrefix="useown" Assembly="OwnControl" %>
<html xmlns="http://www.w3.org/1999/xhtml" >
<head runat="server">
<title>无标题页</title>
</head>
<body>
<form id="form1" runat="server">
<div>
<useown:BarGrphaControl ID="user1" runat="server" EnableViewState="true"></useown:BarGrphaControl>
<asp:Button ID="btnOK" runat="server" Text="增加" onclick="btnOK_Click" />
</div>
</form>
</body>
</html>
button事件：
protected void btnOK_Click(object sender, EventArgs e)
{
this.user1.AddValue("123",10);
this.user1.AddValue("456",20);
}
<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
<%@ Register Namespace="OwnControl" TagPrefix="useown" Assembly="OwnControl" %>
<html xmlns="http://www.w3.org/1999/xhtml" >
<head runat="server">
<title>无标题页</title>
</head>
<body>
<form id="form1" runat="server">
<div>
<useown:BarGrphaControl ID="user1" runat="server" EnableViewState="true"></useown:BarGrphaControl>
<asp:Button ID="btnOK" runat="server" Text="增加" onclick="btnOK_Click" />
</div>
</form>
</body>
</html>
button事件：
protected void btnOK_Click(object sender, EventArgs e)
{
this.user1.AddValue("123",10);
this.user1.AddValue("456",20);
}