ASP.NET Tutorial/Sessions/Session Variables — различия между версиями

Материал из .Net Framework эксперт
Перейти к: навигация, поиск
м (1 версия)
 
м (1 версия)
 
(нет различий)

Текущая версия на 11:57, 26 мая 2010

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>