StateBag.cs实现代码 对理解实现自定义状态管理很有帮助。
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/**
* Namespace: System.Web.UI
* Class: StateBag
*
* Author: Gaurav Vaish
* Maintainer: gvaish@iitk.ac.in
* Implementation: yes
* Contact: <gvaish@iitk.ac.in>
* Status: 100%
*
* (C) Gaurav Vaish (2001)
*/
using System;
using System.Web;
using System.Collections;
using System.Collections.Specialized;
namespace System.Web.UI
{
public sealed class StateBag : IStateManager, IDictionary, ICollection, IEnumerable
{
private bool marked;
private HybridDictionary bag;
public StateBag (bool ignoreCase)
{
Initialize (ignoreCase);
}
public StateBag ()
{
Initialize (false);
}
private void Initialize (bool ignoreCase)
{
marked = false;
bag = new HybridDictionary (ignoreCase);
}
public int Count {
get { return bag.Count; }
}
public object this [string key] {
get {
if (key == null || key.Length == 0)
throw new ArgumentException (HttpRuntime.FormatResourceString ("Key_Cannot_Be_Null"));
object val = bag [key];
if (val is StateItem)
return ((StateItem) val).Value;
return null; //
}
set { Add (key, value); }
}
object IDictionary.this [object key] {
get { return this [(string) key] as object; }
set { Add ((string) key, value); }
}
public ICollection Keys {
get { return bag.Keys; }
}
public ICollection Values {
get { return bag.Values; }
}
public StateItem Add (string key, object value)
{
if (key == null || key.Length == 0)
throw new ArgumentException (HttpRuntime.FormatResourceString ("Key_Cannot_Be_Null"));
StateItem val = bag [key] as StateItem; //don't throw exception when null
if(val == null) {
if(value != null || marked) {
val = new StateItem (value);
bag.Add (key, val);
}
}
else if (value == null && !marked)
bag.Remove (key);
else
val.Value = value;
if (val != null && marked) {
val.IsDirty = true;
}
return val;
}
public void Clear ()
{
bag.Clear ();
}
public IDictionaryEnumerator GetEnumerator ()
{
return bag.GetEnumerator ();
}
public bool IsItemDirty (string key)
{
object o = bag [key];
if (o is StateItem)
return ((StateItem) o).IsDirty;
return false;
}
public void Remove (string key)
{
bag.Remove (key);
}
/// <summary>
/// Undocumented
/// </summary>
public void SetItemDirty (string key, bool dirty)
{
if (bag [key] is StateItem)
((StateItem) bag [key]).IsDirty = dirty;
}
internal bool IsTrackingViewState {
get { return marked; }
}
internal void LoadViewState (object state)
{
if(state!=null) {
Pair pair = (Pair) state;
ArrayList keyList = (ArrayList) (pair.First);
ArrayList valList = (ArrayList) (pair.Second);
int valCount = valList.Count;
for(int i = 0; i < keyList.Count; i++) {
if (i < valCount)
Add ((string) keyList [i], valList [i]);
else
Add ((string) keyList [i], null);
}
}
}
internal object SaveViewState ()
{
if(bag.Count > 0) {
ArrayList keyList = null, valList = null;
foreach (string key in bag.Keys) {
StateItem item = (StateItem) bag [key];
if (item.IsDirty) {
if (keyList == null) {
keyList = new ArrayList ();
valList = new ArrayList ();
}
keyList.Add (key);
valList.Add (item.Value);
}
}
if (keyList!=null)
return new Pair (keyList, valList);
}
return null;
}
internal void TrackViewState()
{
marked = true;
}
IEnumerator IEnumerable.GetEnumerator ()
{
return GetEnumerator ();
}
void IStateManager.LoadViewState (object savedState)
{
LoadViewState (savedState);
}
object IStateManager.SaveViewState ()
{
return SaveViewState ();
}
void IStateManager.TrackViewState ()
{
TrackViewState ();
}
bool IStateManager.IsTrackingViewState {
get { return IsTrackingViewState; }
}
void ICollection.CopyTo (Array array, int index)
{
Values.CopyTo (array, index);
}
bool ICollection.IsSynchronized {
get { return false; }
}
object ICollection.SyncRoot
{
get { return this; }
}
void IDictionary.Add (object key, object value)
{
Add ((string) key, value);
}
void IDictionary.Remove (object key)
{
Remove ((string) key);
}
bool IDictionary.Contains (object key)
{
return bag.Contains ((string) key);
}
bool IDictionary.IsFixedSize {
get { return false; }
}
bool IDictionary.IsReadOnly {
get { return false; }
}
#if NET_2_0
public void SetDirty ()
{
foreach (string key in bag.Keys)
SetItemDirty (key, true);
}
#endif
}
}
下面实现自定义状态管理
public class Address:IStateManager
{
private bool _isTrackingViewState;
private StateBag _viewState;
protected StateBag ViewState
{
get
{
if (_viewState == null)
{
_viewState = new StateBag(false);
if (_isTrackingViewState) ((IStateManager)_viewState).TrackViewState();
}
return _viewState;
}
}
bool IStateManager.IsTrackingViewState
{
get
{
return _isTrackingViewState;
}
}
void IStateManager.LoadViewState(object savedState)
{
if (savedState != null)
{
((IStateManager)ViewState).LoadViewState(savedState);
}
}
object IStateManager.SaveViewState()
{
object savedState = null;
if (_viewState != null)
{
savedState =
((IStateManager)_viewState).SaveViewState();
}
return savedState;
}
void IStateManager.TrackViewState()
{
_isTrackingViewState = true;
if (_viewState != null)
{
((IStateManager)_viewState).TrackViewState();
}
}
#endregion
internal void SetDirty()
{
_viewState.SetDirty(true);
}
[
Category("Behavior"),
DefaultValue(""),
Description("城市"),
NotifyParentProperty(true),
]
public String City //主要这里的ViewState 为我们自定义的
{
get { return ViewState["City"] != null ? (string)ViewState["City"] : String.Empty; }
set { ViewState["City"] = value; }
}
}
