HttpSessionState.Add(String, Object) 方法

定义

向会话状态集合添加一个新项。Adds a new item to the session-state collection.

public:
 void Add(System::String ^ name, System::Object ^ value);
public void Add (string name, object value);
member this.Add : string * obj -> unit
Public Sub Add (name As String, value As Object)

参数

name
String

要添加到会话状态集合的项的名称。The name of the item to add to the session-state collection.

value
Object

要添加到会话状态集合的项的值。The value of the item to add to the session-state collection.

示例

下面的示例演示如何使用Add方法将值存储在会话状态中。The following example shows how to store values in session state by using the Add method. 它还演示了如何使用Remove方法删除会话状态中的值。It also shows how to remove values in session state by using the Remove method. Repeater控件用于在网页上显示内容会话状态。A Repeater control is used to display the contents session state on the Web page. 方法用于循环访问会话状态集合并Repeater填充控件。 GetEnumeratorThe GetEnumerator method is used to iterate through the session-state collection and populate the Repeater control.

重要

此示例具有一个接受用户输入的文本框,这是一个潜在的安全威胁。This example has a text box that accepts user input, which is a potential security threat. 默认情况下,ASP.NET 网页验证用户输入是否不包含脚本或 HTML 元素。By default, ASP.NET Web pages validate that user input does not include script or HTML elements. 有关详细信息,请参阅脚本侵入概述For more information, see Script Exploits Overview.

<%@ Page Language="C#" %>

<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">

<script runat="server">

    protected void Button1_Click(object sender, EventArgs e)
    {
        // If both name and value are specified
        // use the Add method to add the item to session-state.
        if (!String.IsNullOrEmpty(TextBox1.Text) &
            !String.IsNullOrEmpty(TextBox2.Text))
        {
            string itemName = Server.HtmlEncode(TextBox1.Text);
            string itemValue = Server.HtmlEncode(TextBox2.Text);
            Session.Add(itemName, itemValue);
            // Refresh the Repeater control.
            RefreshRepeater();
        }
    }

    protected void RefreshRepeater()
    {
        // Use the GetEnumerator method to 
        // iterate through the session-state.
        ArrayList values = new ArrayList();
        System.Collections.IEnumerator ie = Session.GetEnumerator();
        string currentSessionItemName;
        while (ie.MoveNext())
        {
            currentSessionItemName = (string)ie.Current;
            values.Add(new SessionDataDisplay(currentSessionItemName,
                Session[currentSessionItemName].ToString()));
            
        }
        // Bind values ArrayList to Repeater control.
        Repeater1.DataSource = values;
        Repeater1.DataBind();
    }
    
    public class SessionDataDisplay
    {
        private string _name;
        private string _value;

        public SessionDataDisplay(string name, string value)
        {
            this._name = name;
            this._value = value;
        }
        public string Name
        {
            get { return _name; }
        }
        public string Value
        {
            get { return _value; }
        }
    }

    protected void Repeater1_ItemCommand(object source, RepeaterCommandEventArgs e)
    {
        // Determine which item to remove and
        // use the Remove method to remove it.
        RepeaterItem itemToRemove = e.Item;
        string sessionItemToRemove = 
            ((Label)itemToRemove.FindControl("Label1")).Text;
        Session.Remove(sessionItemToRemove);
        // Refresh the Repeater control.
        RefreshRepeater();
    }
</script>

<html xmlns="http://www.w3.org/1999/xhtml" >
<head runat="server">
    <title>HttpSessionState Example</title>
</head>
<body>
    <form id="form1" 
          runat="server" 
          defaultbutton="Button1" 
          defaultfocus="TextBox1">
    <div>
        Name
        <asp:TextBox ID="TextBox1"
                     runat="server"></asp:TextBox>
        <br />
        Value
        <asp:TextBox ID="TextBox2" 
                     runat="server"></asp:TextBox>
        <asp:Button ID="Button1" 
                    runat="server" 
                    OnClick="Button1_Click" 
                    Text="Add" />
        <br />
        <asp:Repeater ID="Repeater1" runat="server" OnItemCommand="Repeater1_ItemCommand">
          <ItemTemplate>
             <br />
                SessionState Item Name:  
                <asp:Label ID="Label1" 
                           runat="server" 
                           Text='<%# DataBinder.Eval(Container.DataItem, "Name") %>'/>,
                SessionState Item Value: 
                <asp:Label ID="Label2" 
                           runat="server" 
                           Text='<%# DataBinder.Eval(Container.DataItem, "Value") %>'/>
                <asp:Button ID="RemoveItem" 
                            Text="Remove" 
                            runat="server" />
          </ItemTemplate>
        </asp:Repeater>
    
    </div>
    </form>
</body>
</html>
<%@ Page Language="VB" %>

<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">

<script runat="server">

    Protected Sub Button1_Click(ByVal sender As Object, ByVal e As System.EventArgs)

        ' If both name and value are specified
        ' use the Add method to add the item to session-state.
        If (Not String.IsNullOrEmpty(TextBox1.Text) And _
            Not String.IsNullOrEmpty(TextBox2.Text)) Then
            
            Dim itemName As String = Server.HtmlEncode(TextBox1.Text)
            Dim itemValue As String = Server.HtmlEncode(TextBox2.Text)
            Session.Add(itemName, itemValue)
            ' Refresh the Repeater control.
            RefreshRepeater()
            
        End If        
    End Sub
    
    Protected Sub RefreshRepeater()
        
        ' Use the GetEnumerator method to 
        ' iterate through the session-state.
        Dim values As ArrayList = New ArrayList()
        Dim ie As System.Collections.IEnumerator = Session.GetEnumerator()
        Dim currentSessionItemName As String
        While (ie.MoveNext())
            
            currentSessionItemName = CType(ie.Current, String)
            values.Add(New SessionDataDisplay(currentSessionItemName, _
                Session(currentSessionItemName).ToString()))
        End While
        ' Bind values ArrayList to Repeater control.
        Repeater1.DataSource = values
        Repeater1.DataBind()
        
    End Sub
    
    Public Class SessionDataDisplay
        
        Private _name As String
        Private _value As String
        
        Public Sub New(ByVal name As String, ByVal value As String)
            
            Me._name = name
            Me._value = value
            
        End Sub
        Public ReadOnly Property Name() As String
            Get
                Return _name
            End Get
        End Property
        
        Public ReadOnly Property Value() As String
            Get
                Return _value
            End Get
        End Property
        
    End Class

    Protected Sub Repeater1_ItemCommand(ByVal source As Object, _
           ByVal e As System.Web.UI.WebControls.RepeaterCommandEventArgs)

        ' Determine which item to remove and
        ' use the Remove method to remove it.
        Dim itemToRemove As RepeaterItem = e.Item
        Dim sessionItemToRemove As String = _
            CType(itemToRemove.FindControl("Label1"), Label).Text
        Session.Remove(sessionItemToRemove)
        ' Refresh the Repeater control.
        RefreshRepeater()
    End Sub
</script>

<html xmlns="http://www.w3.org/1999/xhtml" >
<head runat="server">
    <title>HttpSessionState Example</title>
</head>
<body>
    <form id="form1" 
          runat="server" 
          defaultbutton="Button1" 
          defaultfocus="TextBox1">
    <div>
        Name
        <asp:TextBox ID="TextBox1"
                     runat="server"></asp:TextBox>
        <br />
        Value
        <asp:TextBox ID="TextBox2" 
                     runat="server"></asp:TextBox>
        <asp:Button ID="Button1" 
                    runat="server" 
                    OnClick="Button1_Click" 
                    Text="Add" />
        <br />
        <asp:Repeater ID="Repeater1" runat="server" OnItemCommand="Repeater1_ItemCommand">
          <ItemTemplate>
             <br />
                SessionState Item Name:  
                <asp:Label ID="Label1" 
                           runat="server" 
                           Text='<%# DataBinder.Eval(Container.DataItem, "Name") %>'/>,
                SessionState Item Value: 
                <asp:Label ID="Label2" 
                           runat="server" 
                           Text='<%# DataBinder.Eval(Container.DataItem, "Value") %>'/>
                <asp:Button ID="RemoveItem" 
                            Text="Remove" 
                            runat="server" />
          </ItemTemplate>
        </asp:Repeater>
    
    </div>
    </form>
</body>
</html>

注解

如果参数引用现有的会话状态项, 则使用指定value的覆盖现有项。 nameIf the name parameter refers to an existing session state item, the existing item is overwritten with the specified value.

适用于

另请参阅