作者: 李嘉 日期: 2009-02-09 17:05
我在一些项目中需要对ViewSate进行压缩，网上查阅了很多资料，发现每个方法方案都不完善，导致压缩ViewState后页面功能出现各种各样的问题，例如以下资料：
3. 压缩 ViewState 后，与 UpdatePanel 的兼容问题
但是这些方法的有利有弊，主要是功能上并不完善，导致Ajax的一些应用功能失败，特别是updatepanel中的一些服务端控件的服务端事件无法触发。Google搜索了很多资料没能找到很好的解决方案，于是我研究一下，结合以上链接的几个方法自定义了一套方案，代码如下：
首先：
using System.IO;
using ICSharpCode.SharpZipLib.Zip.Compression;
------------------------
#region 压缩viewstate
/**/
/// <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)
{
if (Utils.IsMsAjaxCallback(Request))
{
LosFormatter lf = new LosFormatter();
using (StringWriter writer = new StringWriter())
{
lf.Serialize(writer, pViewState);
string viewStateString = writer.ToString();
byte[] data = Convert.FromBase64String(viewStateString);
data = Utils.Compress(data);
ScriptManager.RegisterHiddenField(this, "__COMPRESSEDVS", Convert.ToBase64String(data));
}
}
else
{
//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()
{
string viewState = Request.Form["__COMPRESSEDVS"];
if (viewState != null)
{
byte[] data = Convert.FromBase64String(viewState);
data = Utils.Decompress(data);
LosFormatter lf = new LosFormatter();
return lf.Deserialize(Convert.ToBase64String(data));
}
else
{
//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;
}
}
mStream.Close();
return mMemory.ToArray();
}
#endregion
附件：
1. 其中压缩组件: SharpZipLib , 或者直接这里下：Assemblies for .NET 1.1, .NET 2.0, .NET CF 1.0, .NET CF 2.0: Download [228 KB]
2. 'Utils' 类这里下载: Utils.cs (1.15 kb)