StateManagedCollection StateManagedCollection StateManagedCollection StateManagedCollection Class

定义

为管理 IStateManager 对象的所有强类型集合提供基类。Provides a base class for all strongly typed collections that manage IStateManager objects.

public ref class StateManagedCollection abstract : System::Collections::IList, System::Web::UI::IStateManager
public abstract class StateManagedCollection : System.Collections.IList, System.Web.UI.IStateManager
type StateManagedCollection = class
    interface IList
    interface ICollection
    interface IEnumerable
    interface IStateManager
Public MustInherit Class StateManagedCollection
Implements IList, IStateManager
继承
StateManagedCollectionStateManagedCollectionStateManagedCollectionStateManagedCollection
派生
实现

示例

下面的代码示例演示如何从StateManagedCollection派生一个强类型化集合类以包含IStateManager对象。The following code example demonstrates how to derive a strongly typed collection class from StateManagedCollection to contain IStateManager objects. 在此示例中, CycleCollection派生了包含抽象CycleBicycle (可以是或Tricycle对象) 的实例。In this example, the CycleCollection is derived to contain instances of the abstract Cycle class, which can be either Bicycle or Tricycle objects. 类实现接口, 因为它将CycleColor属性的值存储在视图状态中。 IStateManager CycleThe Cycle class implements the IStateManager interface because it stores the value of the CycleColor property in view state.

namespace Samples.AspNet.CS.Controls {

    using System;
    using System.Security.Permissions;
    using System.Collections;
    using System.ComponentModel;
    using System.Drawing;           
    using System.Web;
    using System.Web.UI;            
    //////////////////////////////////////////////////////////////
    //
    // The strongly typed CycleCollection class is a collection
    // that contains Cycle class instances, which implement the
    // IStateManager interface.
    //
    //////////////////////////////////////////////////////////////
    [AspNetHostingPermission(SecurityAction.Demand, 
        Level=AspNetHostingPermissionLevel.Minimal)]
    public sealed class CycleCollection : StateManagedCollection {
        
        private static readonly Type[] _typesOfCycles 
            = new Type[] { typeof(Bicycle), typeof(Tricycle) };

        protected override object CreateKnownType(int index) {
            switch(index) {
                case 0:
                    return new Bicycle();
                case 1:
                    return new Tricycle();                    
                default:
                    throw new ArgumentOutOfRangeException("Unknown Type");
            }            
        }

        protected override Type[] GetKnownTypes() {
            return _typesOfCycles;
        }

        protected override void SetDirtyObject(object o) {
            ((Cycle)o).SetDirty();
        }

    }
    //////////////////////////////////////////////////////////////
    //
    // The abstract Cycle class represents bicycles and tricycles.
    //
    //////////////////////////////////////////////////////////////
    public abstract class Cycle : IStateManager {

        protected internal Cycle(int numWheels) : this(numWheels, "Red"){ }
        
        protected internal Cycle(int numWheels, String color) {    
            numberOfWheels = numWheels;
            CycleColor = color;
        }
        
        private int numberOfWheels = 0;
        public int NumberOfWheels {
            get { return numberOfWheels; }
        }
        
        public string CycleColor {
            get { 
                object o = ViewState["Color"];
                return (null == o) ? String.Empty : o.ToString() ;
            }
            set {
                ViewState["Color"] = value;            
            }        
        }

        internal void SetDirty() {
            ViewState.SetDirty(true);
        }
        
        // Because Cycle does not derive from Control, it does not 
        // have access to an inherited view state StateBag object.
        private StateBag viewState;
        private StateBag ViewState {
            get {
                if (viewState == null) {
                    viewState = new StateBag(false);
                    if (isTrackingViewState) {
                        ((IStateManager)viewState).TrackViewState();
                    }
                }
                return viewState;
            }
        }

        // The IStateManager implementation.
        private bool isTrackingViewState;
        bool IStateManager.IsTrackingViewState {
            get {
                return isTrackingViewState;
            }
        }

        void IStateManager.LoadViewState(object savedState) {
            object[] cycleState = (object[]) savedState;
            
            // In SaveViewState, an array of one element is created.
            // Therefore, if the array passed to LoadViewState has 
            // more than one element, it is invalid.
            if (cycleState.Length != 1) {
                throw new ArgumentException("Invalid Cycle View State");
            }
            
            // Call LoadViewState on the StateBag object.
            ((IStateManager)ViewState).LoadViewState(cycleState[0]);
        }

        // Save the view state by calling the StateBag's SaveViewState
        // method.
        object IStateManager.SaveViewState() {
            object[] cycleState = new object[1];

            if (viewState != null) {
                cycleState[0] = ((IStateManager)viewState).SaveViewState();
            }
            return cycleState;
        }

        // Begin tracking view state. Check the private variable, because 
        // if the view state has not been accessed or set, then it is not  
        // being used and there is no reason to store any view state.
        void IStateManager.TrackViewState() {
            isTrackingViewState = true;
            if (viewState != null) {
                ((IStateManager)viewState).TrackViewState();
            }
        }        
    }

    public sealed class Bicycle : Cycle {
    
        // Create a red Cycle with two wheels.
        public Bicycle() : base(2) {}    
    }
    
    public sealed class Tricycle : Cycle {
    
        // Create a red Cycle with three wheels.
        public Tricycle() : base(3) {}
    }

}
Imports System.Security.Permissions
Imports System.Collections
Imports System.ComponentModel
Imports System.Drawing
Imports System.Web
Imports System.Web.UI
 
Namespace Samples.AspNet.VB.Controls
    '////////////////////////////////////////////////////////////
    '
    ' The strongly typed CycleCollection class is a collection
    ' that contains Cycle class instances, which implement the
    ' IStateManager interface.
    '
    '////////////////////////////////////////////////////////////
    <AspNetHostingPermission(SecurityAction.Demand, _
        Level:=AspNetHostingPermissionLevel.Minimal)> _
                   Public NotInheritable Class CycleCollection
        Inherits StateManagedCollection

        Private Shared _typesOfCycles() As Type = _
            {GetType(Bicycle), GetType(Tricycle)}

        Protected Overrides Function CreateKnownType(ByVal index As Integer) As Object
            Select Case index
                Case 0
                    Return New Bicycle()
                Case 1
                    Return New Tricycle()
                Case Else
                    Throw New ArgumentOutOfRangeException("Unknown Type")
            End Select

        End Function


        Protected Overrides Function GetKnownTypes() As Type()
            Return _typesOfCycles

        End Function


        Protected Overrides Sub SetDirtyObject(ByVal o As Object)
            CType(o, Cycle).SetDirty()

        End Sub
    End Class
    '////////////////////////////////////////////////////////////
    '
    ' The abstract Cycle class represents bicycles and tricycles.
    '
    '////////////////////////////////////////////////////////////

    MustInherit Public Class Cycle
        Implements IStateManager


        Friend Protected Sub New(ByVal numWheels As Integer) 
            MyClass.New(numWheels, "Red")

        End Sub

        Friend Protected Sub New(ByVal numWheels As Integer, ByVal color As String) 
            numOfWheels = numWheels
            CycleColor = color

        End Sub

        Private numOfWheels As Integer = 0    
        Public ReadOnly Property NumberOfWheels() As Integer 
            Get
                Return numOfWheels
            End Get
        End Property 

        Public Property CycleColor() As String 
            Get
                Dim o As Object = ViewState("Color")
                If o Is Nothing Then 
                    Return String.Empty
                Else  
                    Return o.ToString()
                End If            
            End Get
            Set
                ViewState("Color") = value
            End Set
        End Property


        Friend Sub SetDirty() 
            ViewState.SetDirty(True)

        End Sub

        ' Because Cycle does not derive from Control, it does not 
        ' have access to an inherited view state StateBag object.
        Private cycleViewState As StateBag

        Private ReadOnly Property ViewState() As StateBag 
            Get
                If cycleViewState Is Nothing Then
                    cycleViewState = New StateBag(False)
                    If trackingViewState Then
                        CType(cycleViewState, IStateManager).TrackViewState()
                    End If
                End If
                Return cycleViewState
            End Get
        End Property

        ' The IStateManager implementation.
        Private trackingViewState As Boolean

        ReadOnly Property IsTrackingViewState() As Boolean _
            Implements IStateManager.IsTrackingViewState
            Get
                Return trackingViewState
            End Get
        End Property


        Sub LoadViewState(ByVal savedState As Object) _
            Implements IStateManager.LoadViewState
            Dim cycleState As Object() = CType(savedState, Object())

            ' In SaveViewState, an array of one element is created.
            ' Therefore, if the array passed to LoadViewState has 
            ' more than one element, it is invalid.
            If cycleState.Length <> 1 Then
                Throw New ArgumentException("Invalid Cycle View State")
            End If

            ' Call LoadViewState on the StateBag object.
            CType(ViewState, IStateManager).LoadViewState(cycleState(0))

        End Sub


        ' Save the view state by calling the StateBag's SaveViewState
        ' method.
        Function SaveViewState() As Object Implements IStateManager.SaveViewState
            Dim cycleState(0) As Object

            If Not (cycleViewState Is Nothing) Then
                cycleState(0) = _
                CType(cycleViewState, IStateManager).SaveViewState()
            End If
            Return cycleState

        End Function


        ' Begin tracking view state. Check the private variable, because 
        ' if the view state has not been accessed or set, then it is not being 
        ' used and there is no reason to store any view state.
        Sub TrackViewState() Implements IStateManager.TrackViewState
            trackingViewState = True
            If Not (cycleViewState Is Nothing) Then
                CType(cycleViewState, IStateManager).TrackViewState()
            End If

        End Sub
    End Class


    Public NotInheritable Class Bicycle
        Inherits Cycle


        ' Create a red Cycle with two wheels.
        Public Sub New()
            MyBase.New(2)

        End Sub
    End Class

    Public NotInheritable Class Tricycle
        Inherits Cycle


        ' Create a red Cycle with three wheels.
        Public Sub New()
            MyBase.New(3)

        End Sub
    End Class
End Namespace

注解

IStateManager ParameterCollection类是TreeNodeBindingCollection DataControlFieldCollection存储StyleCollection元素的所有强类型集合 (包括、、、和其他集合) 的基类。 StateManagedCollectionThe StateManagedCollection class is the base class for all strongly typed collections that store IStateManager elements, including DataControlFieldCollection, ParameterCollection, StyleCollection, TreeNodeBindingCollection, and others. StateManagedCollection集合管理其自己的状态以及它所包含的元素的状态。The StateManagedCollection collection manages its own state as well as the state of the elements it contains. 因此, 对的调用IStateManager.SaveViewState将保存集合的状态和集合当前包含的所有元素的状态。Therefore, a call to IStateManager.SaveViewState saves the state of the collection and the state of all the elements currently contained by the collection.

StateManagedCollection类派生时要考虑的最重要的方法是CreateKnownTypeGetKnownTypesOnValidate SetDirty、和SetDirtyObjectThe most important methods to consider when deriving from the StateManagedCollection class are CreateKnownType, GetKnownTypes, OnValidate, SetDirty, and SetDirtyObject. CreateKnownTypeGetKnownTypes方法用于为包含的元素的类型在视图状态中存储索引。The CreateKnownType and GetKnownTypes methods are used to store an index in view state for the type of a contained element. 存储索引 (而不是完全限定的类型名称) 可以提高性能。Storing an index rather than a fully qualified type name improves performance. 只要操作集合的元素, 就会调用方法,并根据业务规则验证元素。OnValidateThe OnValidate method is called whenever elements of the collection are manipulated, and validates the elements according to business rules. 目前, OnValidate方法的实现禁止null将对象存储在集合中; 但是, 你可以重写此方法以定义你自己在派生类型中的验证行为。Currently, the implementation of the OnValidate method prohibits null objects from being stored in the collection; however, you can override this method to define your own validation behavior in a derived type. SetDirty方法强制将整个集合序列化为视图状态, 而不只是序列化自上次加载后对状态所做的更改。The SetDirty method forces the entire collection to be serialized to view state, rather than just serializing changes made to state since the last time it was loaded. SetDirtyObject方法是一个抽象方法, 你可以实现此方法以在元素级别执行此相同行为。The SetDirtyObject method is an abstract method you can implement to perform this same behavior at the element level.

重要

StateManagedCollection将集合项的程序集限定类型名称存储在视图状态中。StateManagedCollection stores assembly-qualified type names of the collection items in view state. 站点访问者可以解码视图状态并检索类型名称。A site visitor could decode the view state and retrieve the type name. 如果此方案在您的网站中产生安全问题, 则您可以在将类型名称放入视图状态之前手动对其进行加密。If this scenario creates a security concern in your Web site, you can manually encrypt the type name before placing it in the view state.

构造函数

StateManagedCollection() StateManagedCollection() StateManagedCollection() StateManagedCollection()

初始化 StateManagedCollection 类的新实例。Initializes a new instance of the StateManagedCollection class.

属性

Count Count Count Count

获取 StateManagedCollection 集合中包含的元素的数量。Gets the number of elements contained in the StateManagedCollection collection.

方法

Clear() Clear() Clear() Clear()

StateManagedCollection 集合中删除所有项。Removes all items from the StateManagedCollection collection.

CopyTo(Array, Int32) CopyTo(Array, Int32) CopyTo(Array, Int32) CopyTo(Array, Int32)

从特定的数组索引开始,将 StateManagedCollection 集合的元素复制到数组中。Copies the elements of the StateManagedCollection collection to an array, starting at a particular array index.

CreateKnownType(Int32) CreateKnownType(Int32) CreateKnownType(Int32) CreateKnownType(Int32)

在派生类中替代时,创建实现 IStateManager 的类的实例。When overridden in a derived class, creates an instance of a class that implements IStateManager. 所创建对象的类型基于由 GetKnownTypes() 方法返回的集合的指定成员。The type of object created is based on the specified member of the collection returned by the GetKnownTypes() method.

Equals(Object) Equals(Object) Equals(Object) Equals(Object)

确定指定的对象是否等于当前对象。Determines whether the specified object is equal to the current object.

(Inherited from Object)
GetEnumerator() GetEnumerator() GetEnumerator() GetEnumerator()

返回循环访问 StateManagedCollection 集合的迭代器。Returns an iterator that iterates through the StateManagedCollection collection.

GetHashCode() GetHashCode() GetHashCode() GetHashCode()

作为默认哈希函数。Serves as the default hash function.

(Inherited from Object)
GetKnownTypes() GetKnownTypes() GetKnownTypes() GetKnownTypes()

在派生类中替代时,获取 StateManagedCollection 集合可以包含的 IStateManager 类型的数组。When overridden in a derived class, gets an array of IStateManager types that the StateManagedCollection collection can contain.

GetType() GetType() GetType() GetType()

获取当前实例的 TypeGets the Type of the current instance.

(Inherited from Object)
MemberwiseClone() MemberwiseClone() MemberwiseClone() MemberwiseClone()

创建当前 Object 的浅表副本。Creates a shallow copy of the current Object.

(Inherited from Object)
OnClear() OnClear() OnClear() OnClear()

在派生类中替代时,在 Clear() 方法从集合中删除所有项之前执行附加工作。When overridden in a derived class, performs additional work before the Clear() method removes all items from the collection.

OnClearComplete() OnClearComplete() OnClearComplete() OnClearComplete()

在派生类中替代时,在 Clear() 方法完成从集合中删除所有项之后执行附加工作。When overridden in a derived class, performs additional work after the Clear() method finishes removing all items from the collection.

OnInsert(Int32, Object) OnInsert(Int32, Object) OnInsert(Int32, Object) OnInsert(Int32, Object)

在派生类中替代时,在 IList.Insert(Int32, Object)IList.Add(Object) 方法向集合中添加项之前执行附加工作。When overridden in a derived class, performs additional work before the IList.Insert(Int32, Object) or IList.Add(Object) method adds an item to the collection.

OnInsertComplete(Int32, Object) OnInsertComplete(Int32, Object) OnInsertComplete(Int32, Object) OnInsertComplete(Int32, Object)

在派生类中替代时,在 IList.Insert(Int32, Object)IList.Add(Object) 方法向集合中添加项之后执行附加工作。When overridden in a derived class, performs additional work after the IList.Insert(Int32, Object) or IList.Add(Object) method adds an item to the collection.

OnRemove(Int32, Object) OnRemove(Int32, Object) OnRemove(Int32, Object) OnRemove(Int32, Object)

在派生类中替代时,在 IList.Remove(Object)IList.RemoveAt(Int32) 方法从集合中删除指定项之前执行附加工作。When overridden in a derived class, performs additional work before the IList.Remove(Object) or IList.RemoveAt(Int32) method removes the specified item from the collection.

OnRemoveComplete(Int32, Object) OnRemoveComplete(Int32, Object) OnRemoveComplete(Int32, Object) OnRemoveComplete(Int32, Object)

在派生类中替代时,在 IList.Remove(Object)IList.RemoveAt(Int32) 方法从集合中删除指定项之后执行附加工作。When overridden in a derived class, performs additional work after the IList.Remove(Object) or IList.RemoveAt(Int32) method removes the specified item from the collection.

OnValidate(Object) OnValidate(Object) OnValidate(Object) OnValidate(Object)

在派生类中替代时,验证 StateManagedCollection 集合的一个元素。When overridden in a derived class, validates an element of the StateManagedCollection collection.

SetDirty() SetDirty() SetDirty() SetDirty()

强制将整个 StateManagedCollection 集合序列化为视图状态。Forces the entire StateManagedCollection collection to be serialized into view state.

SetDirtyObject(Object) SetDirtyObject(Object) SetDirtyObject(Object) SetDirtyObject(Object)

在派生类中替代时,指示集合包含的 object 将其全部状态记录到视图状态,而不是仅记录更改信息。When overridden in a derived class, instructs an object contained by the collection to record its entire state to view state, rather than recording only change information.

ToString() ToString() ToString() ToString()

返回表示当前对象的字符串。Returns a string that represents the current object.

(Inherited from Object)

显式界面实现

ICollection.Count ICollection.Count ICollection.Count ICollection.Count

获取 StateManagedCollection 集合中包含的元素的数量。Gets the number of elements contained in the StateManagedCollection collection.

ICollection.IsSynchronized ICollection.IsSynchronized ICollection.IsSynchronized ICollection.IsSynchronized

获取指示 StateManagedCollection 集合是否已同步(线程安全)的值。Gets a value indicating whether the StateManagedCollection collection is synchronized (thread safe). 此方法在所有情况下均返回 falseThis method returns false in all cases.

ICollection.SyncRoot ICollection.SyncRoot ICollection.SyncRoot ICollection.SyncRoot

获取可用于同步对 StateManagedCollection 集合的访问的对象。Gets an object that can be used to synchronize access to the StateManagedCollection collection. 此方法在所有情况下均返回 nullThis method returns null in all cases.

IEnumerable.GetEnumerator() IEnumerable.GetEnumerator() IEnumerable.GetEnumerator() IEnumerable.GetEnumerator()

返回循环访问 StateManagedCollection 集合的迭代器。Returns an iterator that iterates through the StateManagedCollection collection.

IList.Add(Object) IList.Add(Object) IList.Add(Object) IList.Add(Object)

StateManagedCollection 集合中添加一个项。Adds an item to the StateManagedCollection collection.

IList.Clear() IList.Clear() IList.Clear() IList.Clear()

StateManagedCollection 集合中删除所有项。Removes all items from the StateManagedCollection collection.

IList.Contains(Object) IList.Contains(Object) IList.Contains(Object) IList.Contains(Object)

确定 StateManagedCollection 集合中是否包含特定值。Determines whether the StateManagedCollection collection contains a specific value.

IList.IndexOf(Object) IList.IndexOf(Object) IList.IndexOf(Object) IList.IndexOf(Object)

确定 StateManagedCollection 集合中的指定项的索引。Determines the index of a specified item in the StateManagedCollection collection.

IList.Insert(Int32, Object) IList.Insert(Int32, Object) IList.Insert(Int32, Object) IList.Insert(Int32, Object)

将项在指定索引处插入 StateManagedCollection 集合中。Inserts an item into the StateManagedCollection collection at the specified index.

IList.IsFixedSize IList.IsFixedSize IList.IsFixedSize IList.IsFixedSize

获取指示 StateManagedCollection 集合是否具有固定大小的值。Gets a value indicating whether the StateManagedCollection collection has a fixed size. 此方法在所有情况下均返回 falseThis method returns false in all cases.

IList.IsReadOnly IList.IsReadOnly IList.IsReadOnly IList.IsReadOnly

获取指示 StateManagedCollection 集合是否为只读的值。Gets a value indicating whether the StateManagedCollection collection is read-only.

IList.Item[Int32] IList.Item[Int32] IList.Item[Int32] IList.Item[Int32]

获取指定索引处的 IStateManager 元素。Gets the IStateManager element at the specified index.

IList.Remove(Object) IList.Remove(Object) IList.Remove(Object) IList.Remove(Object)

StateManagedCollection 集合中删除指定对象的第一个匹配项。Removes the first occurrence of the specified object from the StateManagedCollection collection.

IList.RemoveAt(Int32) IList.RemoveAt(Int32) IList.RemoveAt(Int32) IList.RemoveAt(Int32)

删除指定索引处的 IStateManager 元素。Removes the IStateManager element at the specified index.

IStateManager.IsTrackingViewState IStateManager.IsTrackingViewState IStateManager.IsTrackingViewState IStateManager.IsTrackingViewState

获取指示 StateManagedCollection 集合是否保存对其视图状态的更改的值。Gets a value indicating whether the StateManagedCollection collection is saving changes to its view state.

IStateManager.LoadViewState(Object) IStateManager.LoadViewState(Object) IStateManager.LoadViewState(Object) IStateManager.LoadViewState(Object)

还原 StateManagedCollection 集合以及其包含的 IStateManager 项的以前保存的视图状态。Restores the previously saved view state of the StateManagedCollection collection and the IStateManager items it contains.

IStateManager.SaveViewState() IStateManager.SaveViewState() IStateManager.SaveViewState() IStateManager.SaveViewState()

保存自页回发到服务器后对 StateManagedCollection 集合和该集合包含的每个 IStateManager 对象所做的更改。Saves the changes to the StateManagedCollection collection and each IStateManager object it contains since the time the page was posted back to the server.

IStateManager.TrackViewState() IStateManager.TrackViewState() IStateManager.TrackViewState() IStateManager.TrackViewState()

使 StateManagedCollection 集合及其包含的每个 IStateManager 对象跟踪对它们的视图状态所做的更改,以使它们可以在相同页的请求之间得以保持。Causes the StateManagedCollection collection and each of the IStateManager objects it contains to track changes to their view state so they can be persisted across requests for the same page.

扩展方法

Cast<TResult>(IEnumerable) Cast<TResult>(IEnumerable) Cast<TResult>(IEnumerable) Cast<TResult>(IEnumerable)

IEnumerable 的元素强制转换为指定的类型。Casts the elements of an IEnumerable to the specified type.

OfType<TResult>(IEnumerable) OfType<TResult>(IEnumerable) OfType<TResult>(IEnumerable) OfType<TResult>(IEnumerable)

根据指定类型筛选 IEnumerable 的元素。Filters the elements of an IEnumerable based on a specified type.

AsParallel(IEnumerable) AsParallel(IEnumerable) AsParallel(IEnumerable) AsParallel(IEnumerable)

启用查询的并行化。Enables parallelization of a query.

AsQueryable(IEnumerable) AsQueryable(IEnumerable) AsQueryable(IEnumerable) AsQueryable(IEnumerable)

IEnumerable 转换为 IQueryableConverts an IEnumerable to an IQueryable.

适用于

另请参阅