ASP.NET Tutorial/Sessions/Session Variables

Содержание

1 A session-aware base page
2 Look for Variables
3 Retrieve the value of an item that you have stored in Session state.
4 Save value in text box to session and read it back (VB.net/C#)
5 Save value to session object and read them back (VB.net)
6 Session counter and application counter (C#)
7 Session counter and application counter (VB)
8 Setting and retrieving objects from the Session using State Service and a base page (C#)
9 Setting and retrieving objects from the Session using State Service and a base page (VB)
10 Sorting a DataView stored in Session state.
11 Store user defined object in Session (C#)
12 Using Session State

A session-aware base page

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

Look for Variables

<% @ Page Language="VB" %>
<html>
<head>
   <title>Look for Variables</title>
</head>
<body>
  <center><h1>Look for Session and Application Variables</h1></center><hr/>
  <%
    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 <br/>")
    Else
      Response.Write("Book: " & Book & "<br/>")
    End If
    If (Chapter = Nothing) Then
      Response.Write("Chapter: Unknown <br/>")
    Else
      Response.Write("Chapter: " & Chapter & "<br/>")
    End If
    If (Publisher = Nothing) Then
      Response.Write("Publisher: Unknown <br/>")
    Else
      Response.Write("Publisher: " & Publisher & "<br/>")
    End If
    If (Author = Nothing) Then
      Response.Write("Author: Unknown <br/>")
    Else
      Response.Write("Author: " & Author & "<br/>")
    End If
  %>
</body>
</html>

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

<%@ 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">
    <div>
    <asp:Label
        id="lblMessage"
        Runat="server" />
    </div>
    </form>
</body>
</html>

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

<%@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>

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

<%@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 +="<b>" & strVariable &"</b>:" & _
         Session(strVariable)&"<br>"
      next
   end sub
</script>
<html><body>
   <form runat="server">
      <asp:Label id="Label1" runat="server"/>
   </form>
</body></html>

Session counter and application counter (C#)

<%@ 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">
    <div>
        <asp:Label ID="lblSessionClicks" runat="server"></asp:Label><br />
        <br />
        <asp:Label ID="lblApplicationClicks" runat="server"></asp:Label><br />
        <br />
        <asp:Button ID="btnPost" runat="server" OnClick="btnPost_Click" Text="Post" />&nbsp;</div>
    </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>

Session counter and application counter (VB)

<%@ 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">
    <div>
        <asp:Label ID="lblSessionClicks" runat="server"></asp:Label><br />
        <br />
        <asp:Label ID="lblApplicationClicks" runat="server"></asp:Label><br />
        <br />
        <asp:Button ID="btnPost" runat="server" Text="Post" />&nbsp;</div>
    </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>

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

<%@ 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">
    <div>
        <asp:TextBox ID="TextBox1" Runat="server"></asp:TextBox>
        <asp:Button ID="Button1" Runat="server" Text="Store in Session" 
         OnClick="Button1_Click" />
        <br />
        <asp:HyperLink ID="HyperLink1" Runat="server" 
         NavigateUrl="NextPage.aspx">Next Page</asp:HyperLink>
    </div>
    </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">
    <div>
    
    </div>
    </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!
    }
}

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

<%@ 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">
    <div>
        <asp:TextBox ID="TextBox1" Runat="server"></asp:TextBox>
        <asp:Button ID="Button1" Runat="server" Text="Store in Session" 
         OnClick="Button1_Click" />
        <br />
        <asp:HyperLink ID="HyperLink1" Runat="server" 
         NavigateUrl="NextPage.aspx">Next Page</asp:HyperLink>
    </div>
    </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">
    <div>
    
    </div>
    </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

Sorting a DataView stored in Session state.

<%@ 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">
     <div>
     <asp:GridView
         id="grdProducts"
         AllowSorting="true"
         EnableViewState="false"
         OnSorting="grdProducts_Sorting"
         Runat="server" />
     <br />
     <asp:LinkButton
         id="lnkReload"
         Text="Reload Page"
         Runat="server" />
     </div>
     </form>
</body>
</html>

Store user defined object in Session (C#)

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">
      <div>
   
   <asp:Label id="lblSession" 
              runat="server" 
              Width="472px" 
              Font-Size="Medium" 
              Font-Names="Verdana" 
              Font-Bold="True"></asp:Label>
   <br /><br />
  <div >
  <table>
    <tr>
    <td>
    <asp:ListBox id="lstItems" 
                 Width="208px" 
                 Height="128px" 
                 runat="server"></asp:ListBox>
    </td>
    <td style="padding: 10px">
    <asp:Button id="cmdMoreInfo" 
                Width="120px" 
                Text="More Information" 
                runat="server" 
      OnClick="cmdMoreInfo_Click"></asp:Button>
    <br />
    <br />
    <asp:Label id="lblRecord" 
               runat="server" 
               Width="272px" 
               Font-Size="Small" 
               Font-Names="Verdana" 
               Font-Bold="True"></asp:Label>
    </td>    
    </tr>
  </table>
  </div>
  
  </div>
    </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 += "<br />Number of Objects: ";
    lblSession.Text += Session.Count.ToString();
    lblSession.Text += "<br />Mode: " + Session.Mode.ToString();
    lblSession.Text += "<br />Is Cookieless: ";
    lblSession.Text += Session.IsCookieless.ToString();
    lblSession.Text += "<br />Is New: ";
    lblSession.Text += Session.IsNewSession.ToString();
    lblSession.Text += "<br />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 += "<br />Manufacturer: ";
      lblRecord.Text += piece.Description;
      lblRecord.Text += "<br />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;
  }
}

Using Session State

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">
    <div>
    <h1>Session item added!</h1>
    </div>
    </form>
</body>
</html>

ASP.NET Tutorial/Sessions/Session Variables

Содержание

A session-aware base page

Look for 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

Навигация

Персональные инструменты

Пространства имён

Варианты

Просмотры

Ещё

Поиск

Разделы

Инструменты

Навигация