压缩ASP.NET中的ViewState

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摘要：文章：压缩ASP.NET中的ViewState 摘要：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，发表于北京联高软件有限公司技术文章栏目，代码以高亮显示。
关键字：压缩, viewstate, pbytes, new, system, compression, string, mstream, mmemory, web, icsharpcode, ui, sharpziplib, page

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

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