asp.net viewstate--statebag

ViewState相信大家都会使用,可ViewState到底是什么,又有多少人知道呢

StateBag类这个就不用多说啦吧

在Asp.net 2.0 里,用到StateBag有以下几种

1 Control._viewState  这个就是大家使用的ViewState
2 WebControl.attrState这个是存放Attribute的
3 Style.statebag是存放样式的
4.CssStyleCollection. StateBag

.......
Page生命周期内SaveAllState时

需要先生成个Piar类,
在 调用this.SavePageStateToPersistenceMedium(pair1);时,将其序列化

注意:Asp.net2.0只实现了HiddenFieldPageStatePersister,用户可以从重写,或者使用ControlAdapter提供其它形式的进理机制

HiddenFieldPageStatePersister.Save时会过pair1进行序列化

序列化时,.net提供了三种方式
1使用密钥
2.使用Mac
3不使用

 

  this.Serialize(outputStream, stateGraph);
 outputStream.SetLength(outputStream.Position);
 byte[] buf = outputStream.GetBuffer();
  int length = (int)outputStream.Length;

先序列化

//判断当前Page.RequiresViewStateEncryptionInternal属性返回值是不是需要加密,               
//如果未调用Page.RegisterRequiresViewStateEncryption,则默认为false                
//如果界面设置了RegisterRequiresViewStateEncryption和EnableViewStateMac,加密优先于Mac
                
if ((this._page != null) && this._page.RequiresViewStateEncryptionInternal)    //加密                
{                    
    buf = MachineKeySection.EncryptOrDecryptData(true, buf, this.GetMacKeyModifier(), 0, length);                    
    length = buf.Length;               
}               
else if (((this._page != null) && this._page.EnableViewStateMac) || (this._macKeyBytes != null))//设置可以使用Mac                
{                    
    buf = MachineKeySection.GetEncodedData(buf, this.GetMacKeyModifier(), 0, ref length);                
}

           
text = Convert.ToBase64String(buf, 0, length); // null of either
谈到这,很多人要问pair1里放的是什么,我画了一幅图,详细说明了一下

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

namespace System.Web.UI
{
    using System;
    using System.Collections;
    using System.Collections.Specialized;
    using System.Reflection;
    using System.Security.Permissions;
    using System.Web;
    using System.Web.Util;

    [AspNetHostingPermission(SecurityAction.LinkDemand, Level=AspNetHostingPermissionLevel.Minimal)]
    public sealed class StateBag : IStateManager, IDictionary, ICollection, IEnumerable
    {
        private IDictionary bag;
        private bool ignoreCase;
        private bool marked;

        public StateBag() : this(false)
        {
        }

        public StateBag(bool ignoreCase)
        {
            this.marked = false;
            this.ignoreCase = ignoreCase;
            this.bag = this.CreateBag();
        }

        public StateItem Add(string key, object value)
        {
            if (string.IsNullOrEmpty(key))
            {
                throw ExceptionUtil.ParameterNullOrEmpty("key");
            }
            StateItem item = this.bag[key] as StateItem;
            if (item == null)
            {
                if ((value != null) || this.marked)
                {
                    item = new StateItem(value);
                    this.bag.Add(key, item);
                }
            }
            else if ((value == null) && !this.marked)
            {
                this.bag.Remove(key);
            }
            else
            {
                item.Value = value;
            }
            if ((item != null) && this.marked)
            {
                item.IsDirty = true;
            }
            return item;
        }

        public void Clear()
        {
            this.bag.Clear();
        }

        private IDictionary CreateBag()
        {
            return new HybridDictionary(this.ignoreCase);
        }

        public IDictionaryEnumerator GetEnumerator()
        {
            return this.bag.GetEnumerator();
        }

        public bool IsItemDirty(string key)
        {
            StateItem item = this.bag[key] as StateItem;
            return ((item != null) && item.IsDirty);
        }

        internal void LoadViewState(object state)
        {
            if (state != null)
            {
                ArrayList list = (ArrayList) state;
                for (int i = 0; i < list.Count; i += 2)
                {
                    string key = ((IndexedString) list[i]).Value;
                    object obj2 = list[i + 1];
                    this.Add(key, obj2);
                }
            }
        }

        public void Remove(string key)
        {
            this.bag.Remove(key);
        }

        internal object SaveViewState()
        {
            ArrayList list = null;
            if (this.bag.Count != 0)
            {
                IDictionaryEnumerator enumerator = this.bag.GetEnumerator();
                while (enumerator.MoveNext())
                {
                    StateItem item = (StateItem) enumerator.Value;
                    if (item.IsDirty)
                    {
                        if (list == null)
                        {
                            list = new ArrayList();
                        }
                        list.Add(new IndexedString((string) enumerator.Key));
                        list.Add(item.Value);
                    }
                }
            }
            return list;
        }

        public void SetDirty(bool dirty)
        {
            if (this.bag.Count != 0)
            {
                foreach (StateItem item in this.bag.Values)
                {
                    item.IsDirty = dirty;
                }
            }
        }

        public void SetItemDirty(string key, bool dirty)
        {
            StateItem item = this.bag[key] as StateItem;
            if (item != null)
            {
                item.IsDirty = dirty;
            }
        }

        void ICollection.CopyTo(Array array, int index)
        {
            this.Values.CopyTo(array, index);
        }

        void IDictionary.Add(object key, object value)
        {
            this.Add((string) key, value);
        }

        bool IDictionary.Contains(object key)
        {
            return this.bag.Contains((string) key);
        }

        void IDictionary.Remove(object key)
        {
            this.Remove((string) key);
        }

        IEnumerator IEnumerable.GetEnumerator()
        {
            return this.GetEnumerator();
        }

        void IStateManager.LoadViewState(object state)
        {
            this.LoadViewState(state);
        }

        object IStateManager.SaveViewState()
        {
            return this.SaveViewState();
        }

        void IStateManager.TrackViewState()
        {
            this.TrackViewState();
        }

        internal void TrackViewState()
        {
            this.marked = true;
        }

        public int Count
        {
            get
            {
                return this.bag.Count;
            }
        }

        internal bool IsTrackingViewState
        {
            get
            {
                return this.marked;
            }
        }

        public object this[string key]
        {
            get
            {
                if (string.IsNullOrEmpty(key))
                {
                    throw ExceptionUtil.ParameterNullOrEmpty("key");
                }
                StateItem item = this.bag[key] as StateItem;
                if (item != null)
                {
                    return item.Value;
                }
                return null;
            }
            set
            {
                this.Add(key, value);
            }
        }

        public ICollection Keys
        {
            get
            {
                return this.bag.Keys;
            }
        }

        bool ICollection.IsSynchronized
        {
            get
            {
                return false;
            }
        }

        object ICollection.SyncRoot
        {
            get
            {
                return this;
            }
        }

        bool IDictionary.IsFixedSize
        {
            get
            {
                return false;
            }
        }

        bool IDictionary.IsReadOnly
        {
            get
            {
                return false;
            }
        }

        object IDictionary.this[object key]
        {
            get
            {
                return this[(string) key];
            }
            set
            {
                this[(string) key] = value;
            }
        }

        bool IStateManager.IsTrackingViewState
        {
            get
            {
                return this.IsTrackingViewState;
            }
        }

        public ICollection Values
        {
            get
            {
                return this.bag.Values;
            }
        }
    }
}