ASP.NET小技巧:重写ViewState的存储目的地,以提高页面性能

王朝asp·作者佚名  2006-11-24
窄屏简体版  字體: |||超大  

在 ASP.NET 中,ViewState 因为在客户端的 HTML 里占据大量的空间,并随着页面的 PostBack 反复传递于网络中,一直为人垢病。但是实际上 ViewState 可以存储到数据库、缓存等任意地方,从而避免频繁将冗长的 base64 字符串发送到客户端。这样做不但可以显著提高性能(大幅度减少了网络传输的字节数),而且如果其中的内容也不会被轻易解密和破解。因此这个方法是很有用处的。

以下写了一个简单的例子,用缓存来作为 ViewState 存储目的地。至于缓存的 Key,文中给出的只是一个简单的写法,具体可以根据情况给出严密的方案。

代码大致演示如下:

<%@ Page language="c#" Codebehind="SaveViewStateToOther.aspx.cs" AutoEventWireup="false" Inherits="LinkedList.SaveViewStateToOther" %>

<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.0 Transitional//EN" >

<html>

<head>

<title>SaveViewStateToOther</title>

<meta name="GENERATOR" Content="Microsoft Visual Studio .NET 7.1">

<meta name="CODE_LANGUAGE" Content="C#">

<meta name=vs_defaultClientScript content="JavaScript">

<meta name=vs_targetSchema content="http://schemas.microsoft.com/intellisense/ie5">

</head>

<body MS_POSITIONING="GridLayout">

<form id="Form1" method="post" runat="server"><asp:DataGrid id=DataGrid1 style="Z-INDEX: 101; LEFT: 104px; POSITION: absolute; TOP: 72px" runat="server" BorderColor="#3366CC" BorderStyle="None" BorderWidth="1px" BackColor="White" CellPadding="4" PageSize="6" AllowPaging="True">

<selecteditemstyle font-bold="True" forecolor="#CCFF99" backcolor="#009999">

</SelectedItemStyle>

<itemstyle forecolor="#003399" backcolor="White">

</ItemStyle>

<headerstyle font-bold="True" forecolor="#CCCCFF" backcolor="#003399">

</HeaderStyle>

<footerstyle forecolor="#003399" backcolor="#99CCCC">

</FooterStyle>

<pagerstyle horizontalalign="Left" forecolor="#003399" backcolor="#99CCCC" pagebuttoncount="20" mode="NumericPages">

</PagerStyle>

</asp:DataGrid>

</form>

</body>

</html>

using System;

using System.Data;

using System.IO;

using System.Text;

using System.Web.UI;

using System.Web.UI.WebControls;

namespace LinkedList

{

/// <summary>

/// SaveViewStateToOther 的摘要说明。

/// </summary>

public class SaveViewStateToOther : Page

{

protected DataGrid DataGrid1;

private void Page_Load(object sender, EventArgs e)

{

if (!IsPostBack)

Bind();

}

private void Bind()

{

DataTable table = new DataTable();

table.Columns.Add("id", typeof (int));

table.Columns.Add("name", typeof (string));

for (int i = 0; i < 1000; i++)

{

DataRow row = table.NewRow();

row["id"] = i;

row["name"] = "student_" + i.ToString();

table.Rows.Add(row);

}

DataGrid1.DataSource = table;

DataGrid1.DataBind();

}

#region Web 窗体设计器生成的代码

protected override void OnInit(EventArgs e)

{

InitializeComponent();

base.OnInit(e);

}

private void InitializeComponent()

{

this.DataGrid1.PageIndexChanged += new System.Web.UI.WebControls.DataGridPageChangedEventHandler(this.DataGrid1_PageIndexChanged);

this.Load += new System.EventHandler(this.Page_Load);

}

#endregion

protected override void SavePageStateToPersistenceMedium(object viewState)

{

LosFormatter format = new LosFormatter();

StringWriter writer = new StringWriter();

format.Serialize(writer, viewState);

string vsRaw = writer.ToString();

byte[] buffer = Convert.FromBase64String(vsRaw);

string vsText = Encoding.ASCII.GetString(buffer);

object v = Cache[PageKey];

if (v == null)

Cache.Insert(PageKey, vsText);

else

Cache[PageKey] = vsText;

}

public string PageKey

{

get { return Session.SessionID + "_page_SaveViewStateToOther_aspx"; }

}

protected override object LoadPageStateFromPersistenceMedium()

{

object s = Cache[PageKey];

if (s != null)

{

string state = s.ToString();

byte[] buffer = Encoding.ASCII.GetBytes(state);

 

[1] [2] 下一页

 
 
 
免责声明:本文为网络用户发布,其观点仅代表作者个人观点,与本站无关,本站仅提供信息存储服务。文中陈述内容未经本站证实,其真实性、完整性、及时性本站不作任何保证或承诺,请读者仅作参考,并请自行核实相关内容。
 
 
© 2005- 王朝網路 版權所有 導航