/**//// <summary>
        /// 该值指示控件是否已经初始化
        /// </summary>
        protected bool Initialized
        {
            get
            {
                return initialized;
            }
        }

       public string DataMember
       {
           get
           {
               object member = ViewState["DataMember"];
               if (member == null)
                   return string.Empty;
               else
                   return (string)member;
           }
           set
           {
               ViewState["DataMember"] = value;
               this.OnDataPropertyChanged();
           }
       }

        /**//// <summary>
        /// 为数据绑定控件提供数据源
        /// </summary>
       public IEnumerable DataSource
       {
           get
           {
               return dataSource;
           }
           set
           {
               if ((value is IEnumerable) || (value is IListSource) || (value == null))
                   dataSource = value;
               else
                   throw new Exception("错误的数据源类型");
               OnDataPropertyChanged();
           }
       }

        /**//// <summary>
        /// 数据源控件的 ID 属性
        /// </summary>
        [DefaultValue(""), IDReferenceProperty(typeof(DataSourceControl))]
        public virtual string DataSourceID
        {
            get
            {
                object dataSourceID = ViewState["DataSourceID"];
                if (dataSourceID != null)
                {
                    return (string)dataSourceID;
                }
                return string.Empty;
            }
            set
            {
                this.ViewState["DataSourceID"] = value;
                this.OnDataPropertyChanged();
            }
        }

        /**//// <summary>
        /// 获取是否设置 DataSourceID 属性的值
        /// </summary>
        protected bool IsBoundUsingDataSourceID
        {
            get
            {
                return (DataSourceID.Length > 0);
            }
        }

        /**//// <summary>
        /// 是否需要绑定到其指定的数据源
        /// </summary>
        protected bool RequiresDataBinding
        {
            get
            {
                return requiresDataBinding;
            }
            set
            {
                requiresDataBinding = value;
            }
        }

        /**//// <summary>
        /// 用于检索数据的 DataSourceSelectArguments 对象。默认为 Empty 值
        /// </summary>
        protected DataSourceSelectArguments SelectArguments
        {
            get
            {
                if (selectArguments == null)
                {
                    selectArguments = CreateDataSourceSelectArguments();
                }
                return selectArguments;
            }
        }

       /**//// <summary>
        /// 创建空的 DataSourceSelectArguments 对象
        /// </summary>
        /// <returns></returns>
        protected virtual DataSourceSelectArguments CreateDataSourceSelectArguments()
        {
            return DataSourceSelectArguments.Empty;
        }

       /**//// <summary>
       /// 如果设置了 DataSourceID 属性且数据绑定控件标记为需要绑定，则调用 DataBind 方法
        /// OnPreRender中调用
       /// </summary>
       protected void EnsureDataBound()
       {
           if (RequiresDataBinding && (DataSourceID.Length > 0))
           {
               DataBind();
           }
       }

       

       /**//// <summary>
       /// 在某一基数据源标识属性更改后，将数据绑定控件重新绑定到其数据
       /// </summary>
       protected virtual void OnDataPropertyChanged()
       {
           if (initialized)
           {
               RequiresDataBinding = true;
           }
           currentViewValid = false;
       }

     // 从容器中获取DataControl
       private Control FindControl(Control control, string controlID)
        {
            Control namingContainer = control;
            Control dataControl = null;
            if (control != control.Page)
            {
                while ((dataControl == null) && (namingContainer != control.Page))
                {
                    namingContainer = namingContainer.NamingContainer;
                    if (namingContainer == null)
                    {
                        throw new HttpException("DataBoundControlHelper_NoNamingContainer");
                    }
                    dataControl = namingContainer.FindControl(controlID);
                }
                return dataControl;
            }
            return control.FindControl(controlID);
        }

        /**//// <summary>
        /// 检索与数据绑定控件关联的 IDataSource 接口
        /// </summary>
        /// <returns></returns>
       protected virtual IDataSource GetDataSource()
       {
           if (this.currentDataSource != null)
           {
               return currentDataSource;
           }

           //获取数据源控件
           IDataSource source = null;
           string controlID = DataSourceID;
           if (controlID.Length != 0)
           {
               Control control = FindControl(this, controlID);
               source = control as IDataSource;
           }
           return source;
       }

        private DataSourceView ConnectToDataSourceView()
        {

            if (!currentViewValid || base.DesignMode)
            {
                
                if ((currentView != null) && currentViewIsFromDataSourceID)
                {
                    currentView.DataSourceViewChanged -= new EventHandler(this.OnDataSourceViewChanged);
                }

                this.currentDataSource = GetDataSource();

                //从DataSource获取数据源
                if (this.currentDataSource == null)
                {
                    this.currentDataSource = new ReadOnlyDataSource(DataSource, DataMember);
                }

                DataSourceView view = this.currentDataSource.GetView(DataMember);
                currentViewIsFromDataSourceID = IsBoundUsingDataSourceID;
                currentView = view;
                
                if ((currentView != null) && currentViewIsFromDataSourceID)
                {
                    currentView.DataSourceViewChanged += new EventHandler(this.OnDataSourceViewChanged);
                }
                currentViewValid = true;
            }
            return currentView;
        }

        /**//// <summary>
        /// 获取数据源视图
        /// </summary>
        /// <returns></returns>
        protected virtual DataSourceView GetData()
        {
          return ConnectToDataSourceView();
        }

                if (this.currentDataSource == null)
                {
                    this.currentDataSource = new ReadOnlyDataSource(DataSource, DataMember);
                }

   public class ReadOnlyDataSource : IDataSource
    {
        
        private string _dataMember;
        private object _dataSource;
        private static string[] ViewNames = new string[0];

       
        event EventHandler IDataSource.DataSourceChanged
        {
            add
            {
            }
            remove
            {
            }
        }

        
        public ReadOnlyDataSource(object dataSource, string dataMember)
        {
            this._dataSource = dataSource;
            this._dataMember = dataMember;
        }

        DataSourceView IDataSource.GetView(string viewName)
        {
            IDataSource source = _dataSource as IDataSource;
            if (source != null)
            {
                return source.GetView(viewName);
            }
            return new ReadOnlyDataSourceView(this, this._dataMember,DataSourceHelper.ResolveDataSource(this._dataSource, this._dataMember));
        }

        ICollection IDataSource.GetViewNames()
        {
            return ViewNames;
        }

    }

 public class ReadOnlyDataSourceView : DataSourceView
    {

        private IEnumerable dataSource;

        public ReadOnlyDataSourceView(ReadOnlyDataSource owner, string name, IEnumerable dataSource)
            : base(owner, name)
        {
            this.dataSource=dataSource ;
        }

        protected override IEnumerable ExecuteSelect(DataSourceSelectArguments arguments)
        {
            arguments.RaiseUnsupportedCapabilitiesError(this);
            return dataSource;
        }

    }

        /**//// <summary>
        /// 将数据源绑定到控件
        /// </summary>
        public override void DataBind()
        {
            if (!IsBoundUsingDataSourceID)
            {
                OnDataBinding(EventArgs.Empty);
            }

            GetData().Select(CreateDataSourceSelectArguments(),
                OnDataSourceViewSelectCallback);
            RequiresDataBinding = false;
            MarkAsDataBound();
        }
        private void OnDataSourceViewSelectCallback(IEnumerable retrievedData)
        {
            if (IsBoundUsingDataSourceID)
            {
                OnDataBinding(EventArgs.Empty);
            }
            PerformDataBinding(retrievedData);
        }

        protected override void OnInit(EventArgs e)
        {
            base.OnInit(e);
            if (this.Page != null)
            {
                this.Page.PreLoad += new EventHandler(this.OnPagePreLoad);
                if (!base.IsViewStateEnabled && this.Page.IsPostBack)
                {
                    this.RequiresDataBinding = true;
                }
            }
        }

        private void OnPagePreLoad(object sender, EventArgs e)
        {
            initialized = true;
            if (Page != null)
            {
                Page.PreLoad -= new EventHandler(OnPagePreLoad);
                if (!Page.IsPostBack)
                {
                    RequiresDataBinding = true;
                }
                if ((Page.IsPostBack && base.IsViewStateEnabled) && (ViewState["DataBound"] == null))
                {
                    RequiresDataBinding = true;
                }
            }
        }

        protected override void OnPreRender(EventArgs e)
        {
            EnsureDataBound();
            base.OnPreRender(e);
        }

        protected override void OnLoad(EventArgs e)
        {
            this.initialized = true;
            this.ConnectToDataSourceView();
            if (this.Page != null && this.ViewState["DataBound"] == null)
            {
                if (!this.Page.IsPostBack)
                {
                    this.RequiresDataBinding = true;
                }
                else if (base.IsViewStateEnabled)
                {
                    this.RequiresDataBinding = true;
                }
            }
            base.OnLoad(e);
        }