asp.net 处理原文件中过长的viewstate代码

public class XVPage : Page
{
static private DirectoryInfo _Dir;
private DirectoryInfo Dir
{
get
{
if (_Dir == null)
{
_Dir = new DirectoryInfo(Path.Combine(AppDomain.CurrentDomain.BaseDirectory, "App_Data"));
if (!_Dir.Exists)
_Dir.Create();
_Dir = new DirectoryInfo(Path.Combine(_Dir.FullName, "ViewState"));
if (!_Dir.Exists)
_Dir.Create();
}
return _Dir;
}
}
protected override object LoadPageStateFromPersistenceMedium()
{
PageStatePersister ps = this.PageStatePersister;
ps.Load();
if (ps.ControlState != null)
ps.ControlState = AntiSerialization((string)ps.ControlState);
if (ps.ViewState != null)
ps.ViewState = AntiSerialization((string)ps.ViewState);
return new Pair(ps.ControlState, ps.ViewState);
}
protected override void SavePageStateToPersistenceMedium(object state)
{
PageStatePersister ps = this.PageStatePersister;
if (state is Pair)
{
Pair pair = (Pair)state;
ps.ControlState = pair.First;
ps.ViewState = pair.Second;
}
else
{
ps.ViewState = state;
}
if (ps.ControlState != null)
ps.ControlState = AntiSerialization(ps.ControlState);
if (ps.ViewState != null)
ps.ViewState = AntiSerialization(ps.ViewState);
ps.Save();
}
private object AntiSerialization(string stateID)
{
string stateStr = (string)Cache[stateID];
string file = Path.Combine(Dir.FullName, stateID);
if (stateStr == null)
stateStr = File.ReadAllText(file);
else
Cache.Remove(stateID);
return new ObjectStateFormatter().Deserialize(stateStr);
}
private string AntiSerialization(object obj)
{
string value = new ObjectStateFormatter().Serialize(obj);
string stateID = (DateTime.Now.Ticks + (long)value.GetHashCode()).ToString(); //产生离散的id号码
File.WriteAllText(Path.Combine(Dir.FullName, stateID), value);
Cache.Insert(stateID, value);
return stateID;
}
protected override void OnUnload(EventArgs e)
{
base.OnUnload(e);
DateTime dt = DateTime.Now.AddMinutes(-20);
foreach (FileInfo fl in Dir.GetFiles())
if (fl.LastAccessTime < dt)
try
{
fl.Delete();
}
catch
{
}
}
}