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当用户登录时，我的代码使用System.Web.HttpContext.Current.Session["customer_ref"]在HandleUserLogin()内设置Session变量。可以从@Page访问会话变量，但不能从基础类访问会话变量
我这样做是在下面的类，SessionManager：
SessionManager.cs
using System;
using System.Collections.Generic;
using System.Linq;
using System.Web;
/// <summary>
/// Summary description for Session
/// </summary>
public class SessionManager
{
public string customer_ref;
public bool logged_in = false;
public SessionManager()
{
//
// NULL REFERENCE EXCEPTION CAUSED HERE
//
//
// Check to see if the user is logged in (is a customer reference set?)
if (System.Web.HttpContext.Current.Session["customer_ref"] != null)
{
// The user is logged in
logged_in = true;
}
}
public bool HandleUserLogin(string username, string password)
{
if ((!string.IsNullOrEmpty(username)) && (!string.IsNullOrEmpty(password)))
{
// Check that the username and password are valid
if ((!string.IsNullOrEmpty(username)) && (password == "password"))
{
// Generate a new session ID
// TODO: Find out how to.
// Set the session variables
System.Web.HttpContext.Current.Session["customer_ref"] = username;
// Set the variables of this Session object for future use
this.customer_ref = username;
// Set the logged in status to true
this.logged_in = true;
return true;
}
else
{
// Username and password are incorrect
return false;
}
}
// The username or password was not entered
return false;
}
public void HandleUserLogout()
{
System.Web.HttpContext.Current.Session["customer_ref"] = null;
// Unset the variables in the SessionManager object
this.customer_ref = string.Empty;
// Set the logged in status to false
this.logged_in = false;
}
}
一旦会话变量设置，我很高兴地能够表明它在页面上使用下面的代码和我设置它的值很好地显示。
<%@ Page Language="C#" AutoEventWireup="true" CodeFile="Default.aspx.cs" Inherits="_Default" EnableSessionState="True" %>
<!DOCTYPE html>
<html>
<head>
</head>
<body>
<%
//
// WRITE THE CUSTOMER REFERENCE FROM THE SESSION
//
Response.Write(System.Web.HttpContext.Current.Session["customer_ref"]);
%>
</body>
</html>
但是，我不能从所谓的dashboard.aspx另一个页面访问它，因为它抛出一个NullReferenceException当我打电话给我的SessionManager()类试图在构造访问会话变量。
下面是dashboard.aspx代码，dashboard.aspx.cs：
dashboard.aspx
<%@ Page Language="C#" AutoEventWireup="true" CodeFile="dashboard.aspx.cs" Inherits="dashboard" MasterPageFile="~/Design.master" EnableSessionState="True" %>
<asp:Content ID="customer" ContentPlaceHolderID="CustomerInfo" runat="server">
<div class="customer_name"><% Response.Write(customer.customer_name); %></div>
<div class="customer_account_number">Account number: <% Response.Write(customer.customer_ref); %></div>
</asp:Content>
<asp:Content ID="outstanding_orders" ContentPlaceHolderID="Content" runat="server">
<div class="content_left_title_wrapper">
<h2 class="content_left_title">Your Outstanding Orders</h2>
</div>
<table id="outstanding_orders" cellpadding="0" cellspacing="0">
<colgroup span="4"></colgroup>
<colgroup span="1" class="view_link_col"></colgroup>
<tr>
<th><div>Order Number</div></th>
<th><div>Date Placed</div></th>
<th><div>Total Cost</div></th>
<th><div>Order Status</div></th>
<th></th>
</tr>
<%
// Loop through all of the outstanding orders for the customer
foreach (OrderSummary order_item in outstanding_orders)
{
%>
<tr>
<td><div><% Response.Write(order_item.order_number); %></div></td>
<td><div><% Response.Write(order_item.uk_order_date); %></div></td>
<td><div>£<% Response.Write(order_item.order_total); %></div></td>
<td><div>Incomplete</div></td>
<td><div><a href="orderlines.aspx?orderno=<% Response.Write(order_item.order_number); %>" class="order_detail_link">Detail<br /><img src="images/design/view_order_arrow.png" /></a></div></td>
</tr>
<%
}
%>
</table>
</asp:Content>
dashboard.aspx.cs
using System;
using System.Collections.Generic;
using System.Linq;
using System.Web;
using System.Web.UI;
using System.Web.UI.WebControls;
using IBMU2.UODOTNET;
using System.Xml.Linq;
public partial class dashboard : System.Web.UI.Page
{
// Get the users session
SessionManager session = new SessionManager();
// Create a new connection to the database
ReflexDatabase db_con = new ReflexDatabase();
// Blank list to hold the orders
public List<OrderSummary> outstanding_orders = new List<OrderSummary>();
public XDocument test { get; set; }
public Customer customer;
// OnInit is called before the page loads (See internet for ASP.NET Page Lifecycle)
protected override void OnInit(EventArgs e)
{
if (session.logged_in == false)
{
// I've tried it here, and it won't redirect
Response.Redirect("default.aspx");
}
}
protected void Page_Load(object sender, EventArgs e)
{
try
{
// Create the customer as a Customer object
customer = new Customer(session.customer_ref);
// Query the TOELINE database
XDocument customer_orders = db_con.Query(String.Format("LIST TOEHEAD BY.DSND ORDERNO WITH CUSREF = \"{0}\" AND ORDERSTATUS < 50 ORDERNO DATEONFILE T.VAL.TO.INV ORDERSTATUS TOXML ELEMENTS", customer.customer_ref));
test = customer_orders;
// Use LINQ to pipe the data in to OrderSummary objects
var linqQuery = from n in customer_orders.Element("ROOT").Descendants("TOEHEAD")
select new OrderSummary
{
//order_number = n.Element("ORDERNO").Nodes()..ToString(),
order_number = n.Descendants("ORDERNO").First().Value,
us_order_date = n.Descendants("DATEONFILE").First().Value,
order_total = n.Descendants("T.VAL.TO.INV").First().Value
};
// Add all of the items to the list of orders outstanding for the customer
foreach (OrderSummary linqItem in linqQuery)
{
outstanding_orders.Add(linqItem);
}
}
finally
{
// Close the session to prevent hogging of sessions
db_con.CloseSession();
}
}
}
这里''
@WaqarJanjua请'SessionManager.cs'看到我有注意** NULL引用异常导致**，这是发生异常的地方。 – Luke 2012-08-16 18:32:28
在OnInit和PageLoad方法中创建SessionManager会话对象，而不是在Page级别创建。 – 2012-08-16 18:52:50