压缩ASP.NET中的ViewState的超强改进方法
2013年01月08日
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using System;
using System.IO;
using System.Web;
using System.Web.UI;
using ICSharpCode.SharpZipLib;
namespace WebGenTestApp.CommClass
{
/**//**//**//// <summary>
/// PageClass 的摘要说明。
/// </summary>
public class ViewStateCompressClass : System.Web.UI.Page
{
/**//**//**//**/
/**//**//**//// <summary>
/// 设定序列化后的字符串长度为多少后启用压缩
/// </summary>
private static Int32 LimitLength = 1096;
/**//**//**//**/
/**//**//**//// <summary>
/// 设定压缩比率，压缩比率越高性消耗也将增大
/// </summary>
private static Int32 ZipLevel = ICSharpCode.SharpZipLib.Zip.Compression.Deflater.BEST_COMPRESSION;
/**//**//**//**/
/**//**//**//// <summary>
/// 重写保存页的所有视图状态信息
/// </summary>
/// <param name="pViewState">要在其中存储视图状态信息的对象</param>
protected override void SavePageStateToPersistenceMedium(Object pViewState)
{
//实现一个用于将信息写入字符串的 TextWriter
StringWriter mWriter = new StringWriter();
//序列化 Web 窗体页的视图状态
LosFormatter mFormat = new LosFormatter();
//将有限对象序列化 (LOS) 格式化的对象转换为视图状态值
mFormat.Serialize(mWriter, pViewState);
//将序列化对象转成Base64字符串
String vStateStr = mWriter.ToString();
//设置是否启用了加密方式，默认情况下为不启用
Boolean mUseZip = false;
//判断序列化对象的字符串长度是否超出定义的长度界限
if (vStateStr.Length > LimitLength)
{
//对于长度超出阶线的进行加密，同时将状态设为加密方式
mUseZip = true;
Byte[] pBytes = Compress(vStateStr);
//将字节数组转换为Base64字符串
vStateStr = System.Convert.ToBase64String(pBytes);
}
//注册在页面储存ViewState状态的隐藏文本框，并将内容写入这个文本框
RegisterHiddenField("__MSPVSTATE", vStateStr);
//注册在页面储存是否启用压缩状态的文本框，并将启用状态写入这个文本框
RegisterHiddenField("__MSPVSTATE_ZIP", mUseZip.ToString().ToLower());
}
/**//**//**//**/
/**//**//**//// <summary>
/// 对字符串进行压缩
/// </summary>
/// <param name="pViewState">ViewState字符串</param>
/// <returns>返回流的字节数组</returns>
public static Byte[] Compress(String pViewState)
{
//将存储状态的Base64字串转换为字节数组
Byte[] pBytes = System.Convert.FromBase64String(pViewState);
//创建支持内存存储的流
MemoryStream mMemory = new MemoryStream();
Deflater mDeflater = new Deflater(ZipLevel);
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();
}
/**//**//**//**/
/**//**//**//// <summary>
/// 重写将所有保存的视图状态信息加载到页面对象
/// </summary>
/// <returns>保存的视图状态</returns>
protected override Object LoadPageStateFromPersistenceMedium()
{
//使用Request方法获取序列化的ViewState字符串
String mViewState = this.Request.Form.Get("__MSPVSTATE");
//使和Request方法获取当前的ViewState是否启用了压缩
String mViewStateZip = this.Request.Form.Get("__MSPVSTATE_ZIP");
Byte[] pBytes;
if (mViewStateZip == "true")
{
pBytes = DeCompress(mViewState);
}
else
{
//将ViewState的Base64字符串转换成字节
pBytes = System.Convert.FromBase64String(mViewState);
}
//序列化 Web 窗体页的视图状态
LosFormatter mFormat = new LosFormatter();
//将指定的视图状态值转换为有限对象序列化 (LOS) 格式化的对象
return mFormat.Deserialize(System.Convert.ToBase64String(pBytes));
}
/**//**//**//**/
/**//**//**//// <summary>
/// 解压缩ViewState字符串
/// </summary>
/// <param name="pViewState">ViewState字符串</param>
/// <returns>返回流的字节数组</returns>
public static Byte[] DeCompress(String pViewState)
{
//将Base64字符串转换为字节数组
Byte[] pBytes = System.Convert.FromBase64String(pViewState);
ICSharpCode.SharpZipLib.Zip.Compression.Streams.InflaterInputStream mStream = new ICSharpCode.SharpZipLib.Zip.Compression.Streams.InflaterInputStream(new MemoryStream(pBytes));
//创建支持内存存储的流
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;
}
}
