如果你有在IE中查看当前浏览页面HTML源代码的习惯,你也许常会看到类似以下的代码片断:
  <input type="hidden" name="__VIEWSTATE" value="dDwtMzU5NzUyMTQ1O3Q8O2w8aTwwPjs+O2w8dDw7bDxpPDA+Oz47bDx0PDtsPG
  ……
    聪明的你一定会问,这是什么?有什么作用?它与本篇文章有何转折亲关系?各位看官,且听我慢慢道来。
    其实,这就是MS在Asp.net应用ViewState技术的特征表现。为了页面能在PostBack后依然能读取服务器控 件原有的状态数据,Asp.net中使用了ViewState技术,而ViewState技术本质上是用一个默认名称为"__VIEWSTATE的 Hidden类型表单域来保存和传递数据(这些数据是经过了序列化后Base64编码的字符串值,且是在方法 Page.SavePageStateToPersistenceMedium输出前保存、并由 Page.LoadPageStateFromPersistenceMedium加载)。虽然我们可以通过三种级别来轻松禁用掉这些数据的往返传递:
  Machine级 在machine.config中设置<pages enableViewStateMac='false' />
  Application级 在Web Applicatin的web.config中设置<pages enableViewStateMac='false' />
  单页面级 在该页面中设置<%@Page enableViewStateMac='false' %>或通过代码设置Page.EnableViewStateMac = false;
  
     可是,如果我们完全能通过禁用ViewState来解决数据传输负担而且不产生副作用的话,那MS的架构师们也不会傻到如此可爱的地步(可有可无的东东留 它何用?),正因我们往往不能通过简单的禁用来解决这个传输负担问题,所以我们只能另辟路径使之在网络往返中传输量尽可能地小,于是,压缩成了我们的首 选。只要我们重载Page类的SavePageStateToPersistenceMedium()方法与 LoadPageStateFromPersistenceMedium()方法,并在重载方法中对数据进行压缩与解压的处理即可。开源项目 SharpZipLib提供的类GZipInputStream与GZipOutputStream进入了我们的视野,为了方便,不妨写个类 CompressionHelper,代码如下:
    using System.IO;
    using ICSharpCode.SharpZipLib.GZip;
    
    namespace Ycweb.Components
    {
            /**//// <summary>
            /// Summary de.ion for CompressionHelper.
            /// </summary>
            public class CompressionHelper
            {
                    public CompressionHelper()
                    {
                            //
                            // TODO: Add constructor logic here
                            //
                    }
    
                    /**//// <summary>
                    /// 压缩数据
                    /// </summary>
                    /// <param name="data">待压缩的字节数组</param>
                    /// <returns>压缩后的字节数组</returns>
                    public static byte[] CompressByte(byte[] data)
                    {
                            MemoryStream ms = new MemoryStream();
                            Stream s=new GZipOutputStream(ms);    
                            s.Write( data, 0, data.Length );
                            s.Close();
                            return ms.ToArray();    
                    }
    
                    /**//// <summary>
                    /// 解压数据
                    /// </summary>
                    /// <param name="data">待解压的字节数组</param>
                    /// <returns>解压出的字节数组</returns>
                    public static byte[] DeCompressByte(byte[] data)
                    {
                            byte[] writeData = new byte[2048];
                            MemoryStream ms= new MemoryStream( data );
                            Stream sm = new GZipInputStream(ms) as Stream;
                            MemoryStream outStream = new MemoryStream();
                            while (true)
                            {
                                    int size = sm.Read(writeData,0, writeData.Length );
                                    if (size >0)
                                    {
                                            outStream.Write(writeData,0,size);
                                    }
                                    else
                                    {
                                            break;
                                    }
                            }
                            sm.Close();
                            byte[] outArr = outStream.ToArray();
                            outStream.Close();
                            return outArr;    
                    }
            }
    }
   然后我们在派生于类Page的页面控制基类中重载方法LoadPageStateFromPersistenceMedium()与SavePageStateToPersistenceMedium(Object viewState),代码如下:
#region Load & Save ViewState Data
protected override object    LoadPageStateFromPersistenceMedium()
{
        //从自己注册的隐藏域__SmartViewState中读取数据
        string viewState = Request.Form["__SmartViewState"];
        byte[] bytes = Convert.FromBase64String(viewState);
        //调用上面提供的静态方法CompressionHelper.DeCompressByte()来解压数据
        bytes = CompressionHelper.DeCompressByte(bytes);
        LosFormatter formatter = new LosFormatter();
        return formatter.Deserialize(Convert.ToBase64String(bytes));

}

protected override void SavePageStateToPersistenceMedium(Object viewState)
{
        LosFormatter formatter = new LosFormatter();
        StringWriter writer = new StringWriter();
        formatter.Serialize(writer, viewState);
        string viewStateString = writer.ToString();
        byte[] bytes = Convert.FromBase64String(viewStateString);
        //调用上面提供的静态方法CompressionHelper.CompressByte()来压缩数据
        bytes = CompressionHelper.CompressByte(bytes);

        //注册一个新的隐藏域__SmartViewState,你也可以自己定义
        this.RegisterHiddenField("__SmartViewState", Convert.ToBase64String(bytes));                
}
#endregion

     经过以上处理,web输出页面中的源代码就是型如:
  <input type="hidden" name="__SmartViewState" value="H4sIAPtPoNwA/81ce1PbWJb/ ……
  <input type="hidden" name="__VIEWSTATE" value="" />
      原来的隐藏域"__VIEWSTATE"值为空,而取而代之的是我们自己注册的新的隐藏域"__SmartViewState"来存储了 经过压缩后的字符串,这样以来,提速效果是明显的,结合我们的项目,象DG3G.COM的首页原ViewState串值大约是28K,压缩后为7K,而 Acafa.com的首页原ViewState串值大约是43K,压缩后为8K。这样的处理还是比较令人满意的。当然,如果你觉得还不够彻底,你还可以把 ViewState串存储在Session中,不过这样做,对服务器内存的压力将陡增(尤其是访问量较大的时候),建议还是不要轻易使用,如果你Web服务器内存有个10G、8G的,不妨试试。下面给出相关修改代码:
  将上述LoadPageStateFromPersistenceMedium()方法体中的代码:
      string viewState = Request.Form["__SmartViewState"];
  修改为:
     string viewState = Session["__SmartViewState"].ToString();
  同时,将上述SavePageStateToPersistenceMedium()体中的代码:
     this.RegisterHiddenField("__SmartViewState", Convert.ToBase64String(bytes));
  修改为:
     Session["__SmartViewState"] = Convert.ToBase64String(bytes);
      末了,以上代码和方案均来自VS2003开发实践,对VS2005是否合适,本人不做任何承诺,不过如果你能从以上方案中有所收获,我将感到无比的高兴。