using System;

using System.IO;

using System.Linq;

using System.Runtime.Serialization.Formatters.Binary;

using System.Threading;

using System.Web.UI;



public class VPage : Page

{

    static private DirectoryInfo _Dir;



    private static 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 = 反序列化对象((string)ps.ControlState);

        if (ps.ViewState != null)

            ps.ViewState = 反序列化对象((string)ps.ViewState);

        return new Pair(ps.ControlState, ps.ViewState);

    }



    protected override void SavePageStateToPersistenceMedium(object state)

    {

        PageStatePersister ps = this.PageStatePersister;

        if (state is Pair)

        {

            ps.ControlState = ((Pair)state).First;

            ps.ViewState = ((Pair)state).Second;

        }

        else

            ps.ViewState = state;

        if (ps.ControlState != null)

            ps.ControlState = 序列化对象(ps.ControlState);

        if (ps.ViewState != null)

            ps.ViewState = 序列化对象(ps.ViewState);

        ps.Save();

    }



    private object 反序列化对象(string stateID)

    {

        if (stateID == null)

            return null;



        object state = Cache[stateID];

        if (state == null)

            using (var stream = File.OpenRead(Path.Combine(Dir.FullName, stateID)))

                state = new BinaryFormatter().Deserialize(stream);

        else

            Cache.Remove(stateID);

        return state;

    }



    private string 序列化对象(object obj)

    {

        string stateID = Guid.NewGuid().ToString("N");

        Cache.Insert(stateID, obj, null, DateTime.Now.AddMinutes(5), System.Web.Caching.Cache.NoSlidingExpiration);

        using (var stream = File.Create(Path.Combine(Dir.FullName, stateID)))

            new BinaryFormatter().Serialize(stream, obj);

        return stateID;

    }



    static VPage()

    {

        ThreadPool.QueueUserWorkItem(h =>

        {

            var et = DateTime.Now.AddMinutes(-30);

            Dir.GetFiles()

                .Where(f => f.LastAccessTime < et)

                .ToList()

                .ForEach(f =>

                {

                    try

                    {

                        f.Delete();

                    }

                    catch { }

                });

        });

    }

}

 public class UUHiddenFieldPageStatePersister : HiddenFieldPageStatePersister

    {

        public UUHiddenFieldPageStatePersister(Page page)

            : base(page)

        {

        }



        public override void Load()

        {

            Stream stateStream = new FileStream("ViewStateContent.txt", FileMode.OpenOrCreate);

            // Read the state string, using the StateFormatter.

            StreamReader reader = new StreamReader(stateStream);

            IStateFormatter formatter = this.StateFormatter;

            string fileContents = reader.ReadToEnd();

            // Deserilize returns the Pair object that is serialized in

            // the Save method.

            if (fileContents != "" && fileContents != null)

            {

                string json = (string)formatter.Deserialize(fileContents);

                Pair statePair = JsonConvert.DeserializeObject<Pair>(json);



                ViewState = statePair.First;

                ControlState = statePair.Second;



                reader.Close();

                stateStream.Close();

            }

            //return;

            base.Load();

        }



        public override void Save()

        {

            if (this.ViewState != null || this.ControlState != null)

            {

                if (Page.Session != null)

                {

                    Stream stateStream = new FileStream("ViewStateContent.txt", FileMode.OpenOrCreate);

                    StreamWriter writer = new StreamWriter(stateStream);

                    IStateFormatter formatter = this.StateFormatter;



                    Pair statePair = new Pair(this.ViewState, this.ControlState);

                    // Serialize the statePair object to a string.

                    string json = JsonConvert.SerializeObject(statePair);

                    string serializedState = formatter.Serialize(json);



                    writer.Write(serializedState);



                    writer.Close();

                    stateStream.Close();

                }

                else

                {

                    throw new InvalidOperationException("Session needed for StreamPageStatePersister.");

                }

            }



            //return;

            base.Save();

        }

    }



 public partial class Default : System.Web.UI.Page

    {

        private string TstViewStateKey = "TestTxt";



        private PageStatePersister pageStatePersister = null;

        protected override PageStatePersister PageStatePersister

        {

            get

            {

                //return base.PageStatePersister;

                if (this.pageStatePersister == null)

                {

                    this.pageStatePersister = new UUHiddenFieldPageStatePersister(this);

                }

                return this.pageStatePersister;

            }

        }



  protected void Page_Load(object sender, EventArgs e)

        {

            if (this.IsPostBack == false)

            {

                this.TextBox1.Text = "这是个文本框";

                this.ViewState[TstViewStateKey] = "[123测试文本321]";

            }

        }



   protected void Button1_Click(object sender, EventArgs e)

        {

            string txt = this.ViewState[TstViewStateKey] == null ? "" : this.ViewState[TstViewStateKey].ToString();

            this.Label2.Text = this.TextBox1.Text + txt;

        }

    }