压缩ASP.NET中的ViewState

http://www.cnblogs.com/mack/archive/2005/07/27/201411.html

服务器端控件带来的好外我在这就不多说了，但多过的使用服务器端件保存控件的状态会带来大量的ViewState的情况大家一定遇到过吧．过多的ViewState会很大程度上降低页面的加载速度制成服务器端的性能下降．

以下是结合CSharpZipLib对ViewState进行压缩的方法．

MSPlus.Web.UI.Page 源码：
using System;
using System.Web.UI;
using System.IO;
using ICSharpCode.SharpZipLib.Zip.Compression;

namespace MSPlus.Web.UI
{
/**//// <summary>
/// 压缩ViewState By Mack.Z （MSPlus）
/// </summary>
public class Page : System.Web.UI.Page
{

protected override void SavePageStateToPersistenceMedium(Object pViewState)
{
LosFormatter mFormat = new LosFormatter();
StringWriter mWriter = new StringWriter();

mFormat.Serialize(mWriter, pViewState);
String mViewStateStr = mWriter.ToString();

byte[] pBytes = System.Convert.FromBase64String(mViewStateStr);

pBytes = Compress(pBytes);

String vStateStr = System.Convert.ToBase64String(pBytes);

RegisterHiddenField("__MSPVSTATE", vStateStr);
}

protected override Object LoadPageStateFromPersistenceMedium()
{
String vState = this.Request.Form.Get("__MSPVSTATE");

byte[] pBytes = System.Convert.FromBase64String(vState);

pBytes = DeCompress(pBytes);

LosFormatter mFormat = new LosFormatter();

return mFormat.Deserialize(System.Convert.ToBase64String(pBytes));
}

public static byte[] Compress(byte[] pBytes)
{
MemoryStream mMemory = new MemoryStream();

Deflater mDeflater = new Deflater(ICSharpCode.SharpZipLib.Zip.Compression.Deflater.BEST_COMPRESSION);
ICSharpCode.SharpZipLib.Zip.Compression.Streams.DeflaterOutputStream mStream = new ICSharpCode.SharpZipLib.Zip.Compression.Streams.DeflaterOutputStream(mMemory,mDeflater,131072);

mStream.Write(pBytes,0,pBytes.Length);
mStream.Close();

return mMemory.ToArray();
}

public static byte[] DeCompress(byte[] pBytes)
{
ICSharpCode.SharpZipLib.Zip.Compression.Streams.InflaterInputStream mStream = new ICSharpCode.SharpZipLib.Zip.Compression.Streams.InflaterInputStream(new MemoryStream(pBytes));

MemoryStream mMemory = new MemoryStream();
Int32 mSize;

byte[] mWriteData = new byte[4096];

while(true)
{
mSize = mStream.Read(mWriteData, 0, mWriteData.Length);
if (mSize > 0)
{
mMemory.Write(mWriteData, 0, mSize);
}
else
{
break;
}
}

mStream.Close();
return mMemory.ToArray();
}

}
}

使用方法（ASPX.CS页面继承MSPlus.Web.UI.Page）：public class PageClass : System.Web.UI.Page

测试下来的结果：压缩后的ViewState只有原来的20%!

我作了一个小小的测试.先后用同一个页面加密和不加密的情况下,刷新页面观测w3wp.exe的CPU占用情况.此页面的ViewState大小为3.996 Bytes

w3wp.exe 以下是每次刷新的时CPU的情况

05 03 05 03 06 05 05 08 03 05 03 不加密，平均是 4.6
05 05 06 05 05 03 08 02 03 05 06 加密，平均是5.3