实现自己的视图状态类

.net 视图状态的管理是通过StateBag类来实现的,StateBag把视图存放在StateItem里,本人在了解源代码后,实现自己的视图状态管理类(功能跟.net的一样没有做改动)

 

 

以下是MyStateBag类的实现代码:

 

using System;using System.Collections;using System.Collections.Generic;using System.Collections.Specialized;using System.Text;

using System.Web.UI;

namespace MyControl.CourseOfStudy.MyViewState{    public sealed class MyStateBag:IStateManager    {        // Fields        private IDictionary bag;        private bool ignoreCase; //比较字符串时是否区分大小写        private bool marked;

        // Methods        public MyStateBag():this(false) //注意它的作用，语法        {        }

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

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

        /// <summary>        ///         /// </summary>        /// <param name="key"></param>        /// <param name="value"></param>        /// <returns></returns>        public MyStateItem Add(string key, object value)        {            if (string.IsNullOrEmpty(key))            {                throw new Exception("参数key为空！");            }

            //如果不需要更新的数据不要加入bag中,效率会不会更高？            MyStateItem item = this.bag[key] as MyStateItem;             if (item == null)            {                if ((value != null) || this.marked) //这里marked标志不是针对某个MyStateItem的，而是所有的                {                    item = new MyStateItem(value);                    this.bag.Add(key, item);                }            }            else if ((value == null) && !this.marked) //只有value为null 并且 marked=false时才移走,这说明放在bag中的item包含不需要更新的数据            {                this.bag.Remove(key);            }            else            {                item.Value = value;            }

            if ((item != null) && this.marked)            {                item.IsDirty = true;            }            return item;        }

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

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

        internal object SaveViewState()        {            ArrayList list = null;            if (this.bag.Count != 0)            {                IDictionaryEnumerator enumerator = this.bag.GetEnumerator();                while (enumerator.MoveNext())                {                    //或MyStateItem item = (MyStateItem)enumerator.Current;                    MyStateItem item = (MyStateItem)enumerator.Value;                    if (item.IsDirty)                    {                        if (list == null)                        {                            list = new ArrayList();//在这里才new而不在声明时new是考虑效率，因为如果bag.Count==0就没必要new了                        }                        list.Add(enumerator.Key);                        list.Add(item.Value);                    }                }            }            return list;        }

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

        #region IStateManager 成员

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

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

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

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

        public object this[string key]        {            get             {                if (string.IsNullOrEmpty(key))                {                    throw new Exception("参数key为空！");                }                MyStateItem item = this.bag[key] as MyStateItem;                if (item != null)                {                    return item.Value; //注意MyStateItem里的Value才是视图的值！！！                }                return null;            }            set            {                this.Add(key, value); //！！！            }        }

        #endregion    }}

 

以下是MyStateItem类的实现代码:

 

namespace MyControl.CourseOfStudy.MyViewState{    /// <summary>    /// 视图状态中所装的value,即key对应的value,因为.net框架需要判断每个value的isDirty,所以设计了MyStateItem类    /// </summary>    public sealed class MyStateItem    {        // Fields        private bool isDirty; //是否是脏数据（是否需要保存到视图状态）        private object value;

        // Methods        internal MyStateItem(object initialValue)        {            this.value = initialValue;            this.isDirty = false;        }

        // Properties        public bool IsDirty        {            get             {                 return this.isDirty;            }            set            {                this.isDirty = value;            }        }

        public object Value        {            get            {                return this.value;            }            set            {                this.value = value;            }        }    }}