Содержание

1 A session-aware base page
2 Look for Variables
3 Look for Session and Application Variables
4 Session item added!

A session-aware base page

   <source lang="csharp">

C# version using System; using System.Web; public class SmartSessionPage : System.Web.UI.Page {

   private const string MYKEY = "mykey";
   public string MyKey
   {
       get
       {
           return (string)Session[MYKEY];
       }
       set
       {
           Session[MYKEY] = value;
       }
   }

} VB version Imports Microsoft.VisualBasic Imports System Imports System.Web Public Class SmartSessionPage

   Inherits System.Web.UI.Page
   Private Const MYSESSIONKEY As String = "mykey"
   Public Property MyKey() As String
       Get
           Return CType(Session(MYSESSIONKEY), String)
       End Get
       Set(ByVal value As String)
           Session(MYSESSIONKEY) = value
       End Set
   End Property

End Class</source>

Look for Variables

   <source lang="csharp">

<% @ Page Language="VB" %> <html> <head>

  <title>Look for Variables</title>

</head> <body>

Look for Session and Application Variables

 <%
   Dim Book, Chapter, Publisher, Author As String
   Book = Session("Book")
   Chapter = Session("Chapter")
   Publisher = Application("Publisher")
   Author = Application("Author")
   
   If (Book = Nothing) Then
     Response.Write("Book: Unknown 
")
   Else
     Response.Write("Book: " & Book & "
")
   End If
   If (Chapter = Nothing) Then
     Response.Write("Chapter: Unknown 
")
   Else
     Response.Write("Chapter: " & Chapter & "
")
   End If
   If (Publisher = Nothing) Then
     Response.Write("Publisher: Unknown 
")
   Else
     Response.Write("Publisher: " & Publisher & "
")
   End If
   If (Author = Nothing) Then
     Response.Write("Author: Unknown 
")
   Else
     Response.Write("Author: " & Author & "
")
   End If
 %>

</body> </html></source>

Retrieve the value of an item that you have stored in Session state.

   <source lang="csharp">

<%@ 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">

   void Page_Load()
   {
       lblMessage.Text = Session["message"].ToString();
   }

</script> <html xmlns="http://www.w3.org/1999/xhtml" > <head id="Head1" runat="server">

   <title>Session Get</title>

</head> <body>

   <form id="form1" runat="server">

   <asp:Label
       id="lblMessage"
       Runat="server" />

   </form>

</body> </html></source>

Save value in text box to session and read it back (VB.net/C#)

   <source lang="csharp">

<%@Page Language="VB" %> <script runat="server">

  sub Submit_Click(Sender as Object,e as EventArgs)
     if tbName.Value <>""
        Session("Name ")=tbName.Value
        Response.Write("Hi " & Session("Name ")&"!")
     else
        Response.Write("You forgot to enter a name.")
     end if
  end sub

</script> <html> <body>

  <form runat="server">
     Please enter your name:
     <input type="text" id="tbName" runat="server"/>
     
     <asp:Button id="btSubmit" text="Submit" runat="server" OnClick="Submit_Click" />
  </form>

</body> </html> //////////////////////////// <%@ Page Language="VB" %> <script runat="server">

  sub Page_Load(Sender as Object,e as EventArgs)
     Label1.Text ="Welcome back " & Session("Name ") & "!"
  end sub

</script> <html><body>

  <form runat="server">
     <asp:Label id="Label1" runat="server"/>
  </form>

</body></html> ///////////////////////////// <%@ Page Language="C#" %> <script runat="server">

  void Page_Load(Object Sender, EventArgs e) {
     Label1.Text = "Welcome back " + Session["Name"] + "!";
  }

</script> <html><body>

  <form runat="server">
     <asp:Label id="Label1" runat="server"/>
  </form>

</body></html></source>

Save value to session object and read them back (VB.net)

   <source lang="csharp">

<%@Page Language="VB" %> <script runat="server">

  sub Page_Load(Sender as Object,e as EventArgs)
     dim strVariable as string
     Session("Name")="A "
     Session("FavoriteColor")="Blue "
     Session("EyeColor")="Brown "
     Session("AMessage")="Welcome to my world "
     Session("ASPNET")="asp.net "
     for each strVariable in Session.Contents
        Label1.Text +="" & strVariable &":" & _
        Session(strVariable)&"
"
     next
  end sub

</script> <html><body>

  <form runat="server">
     <asp:Label id="Label1" runat="server"/>
  </form>

</body></html></source>

Session counter and application counter (C#)

   <source lang="csharp">

<%@ Page Language="C#" AutoEventWireup="true" CodeFile="Default.aspx.cs" Inherits="_Default" %> <!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd"> <html xmlns="http://www.w3.org/1999/xhtml" > <head runat="server">

   <title>Chapter 8: Counter</title>

</head> <body>

   <form id="form1" runat="server">

       <asp:Label ID="lblSessionClicks" runat="server"></asp:Label>

       

       <asp:Label ID="lblApplicationClicks" runat="server"></asp:Label>

<asp:Button ID="btnPost" runat="server" OnClick="btnPost_Click" Text="Post" />

   </form>

</body> </html> File: Default.aspx.cs using System; using System.Data; using System.Configuration; using System.Web; using System.Web.Security; using System.Web.UI; using System.Web.UI.WebControls; using System.Web.UI.WebControls.WebParts; using System.Web.UI.HtmlControls; public partial class _Default : System.Web.UI.Page {

   int sessionCount;
   protected void Page_Load(object sender, EventArgs e)
   {
       if (Session["Count"] == null)
       {
           sessionCount = 0;
       }
       else
       {
           sessionCount = Convert.ToInt32(Session["Count"]);
       }
   }
   protected void btnPost_Click(object sender, EventArgs e)
   {
       sessionCount++;
       Session["Count"] = sessionCount;
       lblSessionClicks.Text = "You have clicked the button " + sessionCount + " times.";
       Application.Lock();
       int applicationCount = Convert.ToInt32(Application["HitCount"]);
       applicationCount++;
       Application["HitCount"] = applicationCount;
       Application.UnLock();
       lblApplicationClicks.Text = "All users have clicked the button " + applicationCount + " times.";
   }

}

File: Global.asax <%@ Application Language="C#" %> <script runat="server">

   void Application_Start(object sender, EventArgs e) 
   {
       // Code that runs on application startup
       Application.Add("HitCount", 0);
   }
   
   void Application_End(object sender, EventArgs e) 
   {
       //  Code that runs on application shutdown
   }
       
   void Application_Error(object sender, EventArgs e) 
   { 
       // Code that runs when an unhandled error occurs
   }
   void Session_Start(object sender, EventArgs e) 
   {
       // Code that runs when a new session is started
   }
   void Session_End(object sender, EventArgs e) 
   {
       // Code that runs when a session ends. 
       // Note: The Session_End event is raised only when the sessionstate mode
       // is set to InProc in the Web.config file. If session mode is set to StateServer 
       // or SQLServer, the event is not raised.
   }

</script></source>

Session counter and application counter (VB)

   <source lang="csharp">

<%@ Page Language="VB" AutoEventWireup="false" CodeFile="Default.aspx.vb" Inherits="_Default" %> <!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd"> <html xmlns="http://www.w3.org/1999/xhtml" > <head runat="server">

   <title>Chapter 8: Counter</title>

</head> <body>

   <form id="form1" runat="server">

       <asp:Label ID="lblSessionClicks" runat="server"></asp:Label>

       

       <asp:Label ID="lblApplicationClicks" runat="server"></asp:Label>

<asp:Button ID="btnPost" runat="server" Text="Post" />

   </form>

</body> </html> File: Default.aspx.vb Partial Class _Default

   Inherits System.Web.UI.Page
   Dim iSessionCount As Integer
   Protected Sub Page_Load(ByVal sender As Object, _
           ByVal e As System.EventArgs) Handles Me.Load
       If Session("Count") Is Nothing Then
           iSessionCount = 0
       Else
           iSessionCount = CType(Session("Count"), Integer)
       End If
   End Sub
   Protected Sub btnPost_Click(ByVal sender As Object, ByVal e As System.EventArgs) Handles btnPost.Click
       iSessionCount += 1
       lblSessionClicks.Text = "You have clicked the button " & iSessionCount & " times."
       Application.Lock()
       Dim iApplicationCount As Integer = CType(Application("HitCount"), Integer)
       iApplicationCount += 1
       Application("HitCount") = iApplicationCount
       Application.UnLock()
       lblApplicationClicks.Text = "All users have clicked the button " & iApplicationCount & " times."
   End Sub
   Protected Sub Page_PreRender(ByVal sender As Object, ByVal e As System.EventArgs) Handles Me.PreRender
       Session("Count") = iSessionCount
   End Sub

End Class

File: Global.asax <%@ Application Language="VB" %> <script runat="server">

   Sub Application_Start(ByVal sender As Object, ByVal e As EventArgs)
       " Code that runs on application startup
       Application.Add("HitCount", 0)
   End Sub
   
   Sub Application_End(ByVal sender As Object, ByVal e As EventArgs)
       " Code that runs on application shutdown
   End Sub
       
   Sub Application_Error(ByVal sender As Object, ByVal e As EventArgs)
       " Code that runs when an unhandled error occurs
   End Sub
   Sub Session_Start(ByVal sender As Object, ByVal e As EventArgs)
       " Code that runs when a new session is started
   End Sub
   Sub Session_End(ByVal sender As Object, ByVal e As EventArgs)
       " Code that runs when a session ends. 
       " Note: The Session_End event is raised only when the sessionstate mode
       " is set to InProc in the Web.config file. If session mode is set to StateServer 
       " or SQLServer, the event is not raised.
   End Sub

</script></source>

Setting and retrieving objects from the Session using State Service and a base page (C#)

   <source lang="csharp">

<%@ Page Language="C#" AutoEventWireup="true" CodeFile="Default.aspx.cs" Inherits="_Default" %> <!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.1//EN" "http://www.w3.org/TR/xhtml11/DTD/xhtml11.dtd"> <html xmlns="http://www.w3.org/1999/xhtml" > <head id="Head1" runat="server">

   <title>Session State</title>

</head> <body>

   <form id="form1" runat="server">

       <asp:TextBox ID="TextBox1" Runat="server"></asp:TextBox>
       <asp:Button ID="Button1" Runat="server" Text="Store in Session" 
        OnClick="Button1_Click" />
       

       <asp:HyperLink ID="HyperLink1" Runat="server" 
        NavigateUrl="NextPage.aspx">Next Page</asp:HyperLink>

   </form>

</body> </html> File: Default.aspx.cs using System; using System.Data; using System.Configuration; using System.Web; using System.Web.Security; using System.Web.UI; using System.Web.UI.WebControls; using System.Web.UI.WebControls.WebParts; using System.Web.UI.HtmlControls; public partial class _Default : SmartSessionPage {

   protected void Button1_Click(object sender, EventArgs e)
   {
       string[] names = TextBox1.Text.Split(" ");
       Person p = new Person();
       p.firstName = names[0];
       p.lastName = names[1];
       Session["myperson"] = p;
   }

} File: NextPage.aspx <%@ Page Language="C#" AutoEventWireup="true" CodeFile="NextPage.aspx.cs" Inherits="Retrieve" %> <!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd"> <html xmlns="http://www.w3.org/1999/xhtml" > <head runat="server">

   <title>Untitled Page</title>

</head> <body>

   <form id="form1" runat="server">

   </form>

</body> </html> File: NextPage.aspx.cs using System; using System.Data; using System.Configuration; using System.Collections; using System.Web; using System.Web.Security; using System.Web.UI; using System.Web.UI.WebControls; using System.Web.UI.WebControls.WebParts; using System.Web.UI.HtmlControls;

[Serializable] public class Person {

  public string firstName;
  public string lastName;
  public override string ToString()
  {
     return String.Format("Person Object: {0} {1}", firstName, lastName);
  }

} public class SmartSessionPage : System.Web.UI.Page {

   private const string MYPERSON = "myperson";
   public Person MyPerson
   {
       get
       {
           return (Person)Session[MYPERSON];
       }
       set
       {
           Session[MYPERSON] = value;
       }
   }

} public partial class Retrieve : SmartSessionPage {

   protected void Page_Load(object sender, EventArgs e)
   {
       Person p = MyPerson;
       Response.Write(p); //ToString will be called!
   }

}</source>

Setting and retrieving objects from the Session using State Service and a base page (VB)

   <source lang="csharp">

<%@ Page Language="VB" AutoEventWireup="false" CodeFile="Default.aspx.vb" Inherits="_Default" %> <!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.1//EN" "http://www.w3.org/TR/xhtml11/DTD/xhtml11.dtd"> <html xmlns="http://www.w3.org/1999/xhtml" > <head id="Head1" runat="server">

   <title>Session State</title>

</head> <body>

   <form id="form1" runat="server">

       <asp:TextBox ID="TextBox1" Runat="server"></asp:TextBox>
       <asp:Button ID="Button1" Runat="server" Text="Store in Session" 
        OnClick="Button1_Click" />
       

       <asp:HyperLink ID="HyperLink1" Runat="server" 
        NavigateUrl="NextPage.aspx">Next Page</asp:HyperLink>

   </form>

</body> </html> File: Default.aspx.vb

Partial Class _Default

   Inherits SmartSessionPage
   Protected Sub Button1_Click(ByVal sender As Object, ByVal e As System.EventArgs) Handles Button1.Click
       Dim names As String()
       names = TextBox1.Text.Split(" "c) " " "c creates a char
       Dim p As New Person()
       p.firstName = names(0)
       p.lastName = names(1)
       Session("myperson") = p
   End Sub

End Class File: NextPage.aspx <%@ Page Language="VB" AutoEventWireup="false" CodeFile="NextPage.aspx.vb" Inherits="Retrieve" %> <!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd"> <html xmlns="http://www.w3.org/1999/xhtml" > <head runat="server">

   <title>Untitled Page</title>

</head> <body>

   <form id="form1" runat="server">

   </form>

</body> </html> File: NextPage.aspx.vb Imports Microsoft.VisualBasic Imports System Imports System.Web Partial Class Retrieve

   Inherits SmartSessionPage
   Protected Sub Page_Load(ByVal sender As Object, ByVal e As System.EventArgs) Handles Me.Load
       Dim p As Person = MyPerson
       Response.Write(p) " ToString will be called!
   End Sub

End Class

<Serializable()> _ Public Class Person

   Public firstName As String
   Public lastName As String
   Public Overrides Function ToString() As String
       Return String.Format("Person Object: {0} {1}", firstName, lastName)
   End Function

End Class Public Class SmartSessionPage

   Inherits System.Web.UI.Page
   Private Const MYSESSIONPERSONKEY As String = "myperson"
   Public Property MyPerson() As Person
       Get
           Return CType(Session(MYSESSIONPERSONKEY), Person)
       End Get
       Set(ByVal value As Person)
           Session(MYSESSIONPERSONKEY) = value
       End Set
   End Property

End Class</source>

Sorting a DataView stored in Session state.

   <source lang="csharp">

<%@ Page Language="C#" %> <%@ Import Namespace="System.Data" %> <%@ Import Namespace="System.Data.SqlClient" %> <%@ Import Namespace="System.Web.Configuration" %> <!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd"> <script runat="server">

   DataView dvProducts;
   void Page_Load()
   {
       dvProducts = (DataView)Session["Products"];
       if (dvProducts == null)
       {
           string conString = WebConfigurationManager.ConnectionStrings["Products"]. ConnectionString;
           SqlDataAdapter dad = new SqlDataAdapter("SELECT Id,Title,Director FROM Products", conString);
           DataTable dtblProducts = new DataTable();
           dad.Fill(dtblProducts);
           dvProducts = new DataView(dtblProducts);
           Session["Products"] = dvProducts;
       }
   }
   protected void grdProducts_Sorting(object sender, GridViewSortEventArgs e)
   {
       dvProducts.Sort = e.SortExpression;
   }
   void Page_PreRender()
   {
       grdProducts.DataSource = dvProducts;
       grdProducts.DataBind();
   }

</script> <html xmlns="http://www.w3.org/1999/xhtml" > <head id="Head1" runat="server">

   <title>Session DataView</title>

</head> <body>

    <form id="form1" runat="server">

    <asp:GridView
        id="grdProducts"
        AllowSorting="true"
        EnableViewState="false"
        OnSorting="grdProducts_Sorting"
        Runat="server" />
    

    <asp:LinkButton
        id="lnkReload"
        Text="Reload Page"
        Runat="server" />

    </form>

</body> </html></source>

Store user defined object in Session (C#)

   <source lang="csharp">

File: Default.aspx <%@ Page Language="C#" AutoEventWireup="true" CodeFile="Default.aspx.cs" Inherits="SessionStateExample" %> <!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.1//EN" "http://www.w3.org/TR/xhtml11/DTD/xhtml11.dtd"> <html xmlns="http://www.w3.org/1999/xhtml" > <head runat="server">

   <title>Untitled Page</title>

</head> <body>

   <form id="form1" runat="server">

  <asp:Label id="lblSession" 
             runat="server" 
             Width="472px" 
             Font-Size="Medium" 
             Font-Names="Verdana" 
             Font-Bold="True"></asp:Label>

   <asp:ListBox id="lstItems" 
                Width="208px" 
                Height="128px" 
                runat="server"></asp:ListBox>

   <asp:Button id="cmdMoreInfo" 
               Width="120px" 
               Text="More Information" 
               runat="server" 
     OnClick="cmdMoreInfo_Click"></asp:Button>
   

   

   <asp:Label id="lblRecord" 
              runat="server" 
              Width="272px" 
              Font-Size="Small" 
              Font-Names="Verdana" 
              Font-Bold="True"></asp:Label>

   </form>

</body> </html>

File: Default.aspx.cs using System; using System.Data; using System.Configuration; using System.Collections; using System.Web; using System.Web.Security; using System.Web.UI; using System.Web.UI.WebControls; using System.Web.UI.WebControls.WebParts; using System.Web.UI.HtmlControls; public partial class SessionStateExample : System.Web.UI.Page {

 protected void Page_Load(object sender, EventArgs e)
 {
   if (!this.IsPostBack)
   {
     Product piece1 = new Product("A","A Inc.", 7.9M);
     Product piece2 = new Product("B","B Inc.", 6.5M);
     Product piece3 = new Product("C","C Ltd.", 3.1M);
     Session["Product1"] = piece1;
     Session["Product2"] = piece2;
     Session["Product3"] = piece3;
     lstItems.Items.Add(piece1.Name);
     lstItems.Items.Add(piece2.Name);
     lstItems.Items.Add(piece3.Name);
   }
   lblSession.Text = "Session ID: " + Session.SessionID;
   lblSession.Text += "
Number of Objects: ";
   lblSession.Text += Session.Count.ToString();
   lblSession.Text += "
Mode: " + Session.Mode.ToString();
   lblSession.Text += "
Is Cookieless: ";
   lblSession.Text += Session.IsCookieless.ToString();
   lblSession.Text += "
Is New: ";
   lblSession.Text += Session.IsNewSession.ToString();
   lblSession.Text += "
Timeout (minutes): ";
   lblSession.Text += Session.Timeout.ToString();
 }
 protected void cmdMoreInfo_Click(object sender, EventArgs e)
 {
   if (lstItems.SelectedIndex == -1)
   {
     lblRecord.Text = "No item selected.";
   }
   else
   {
     string key = "Product" +(lstItems.SelectedIndex + 1).ToString();
     Product piece = (Product)Session[key];
     lblRecord.Text = "Name: " + piece.Name;
     lblRecord.Text += "
Manufacturer: ";
     lblRecord.Text += piece.Description;
     lblRecord.Text += "
Cost: " + piece.Cost.ToString("c");
   }
 }

}

class Product

{

   private string name;
   public string Name
   {
       get { return name; }
       set { name = value; }
   }
   private string description;
   public string Description
   {
       get { return description; }
       set { description = value; }
   }
   private decimal cost;
   public decimal Cost
   {
       get { return cost; }
       set { cost = value; }
   }
 public Product(string name, string description,
   decimal cost)
 {
   Name = name;
   Description = description;
   Cost = cost;
 }

}</source>

Using Session State

   <source lang="csharp">

Items stored in Session state are scoped to a particular user. You use Session state to store user preferences or other user-specific data across multiple page requests. Session state has no size limitations. Session state can represent more complex objects than simple strings of text. <%@ 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">

   void Page_Load()
   {
       Session["message"] = "Hello World!";
   }

</script> <html xmlns="http://www.w3.org/1999/xhtml" > <head id="Head1" runat="server">

   <title>Session Set</title>

</head> <body>

   <form id="form1" runat="server">

Session item added!

   </form>

</body> </html></source>

ASP.NET Tutorial/Sessions/Session Variables

Содержание

A session-aware base page

Look for Variables

Look for Session and Application Variables

Retrieve the value of an item that you have stored in Session state.

Save value in text box to session and read it back (VB.net/C#)

Save value to session object and read them back (VB.net)

Session counter and application counter (C#)

Session counter and application counter (VB)

Setting and retrieving objects from the Session using State Service and a base page (C#)

Setting and retrieving objects from the Session using State Service and a base page (VB)

Sorting a DataView stored in Session state.

Store user defined object in Session (C#)

Using Session State

Session item added!

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