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書名： ASP.NET 3.5 Application Architecture and Design
作者名： Vivek Thakur
本章字?jǐn)?shù)： 366字
更新時間： 2021-05-28 17:47:11

Sample Project using Code-Behind

Here is an example of the same guestbook application being coded using code-behind classes:

using System;
using System.Data;
using System.Data.OleDb;
using System.Web;
using System.Web.UI;
using System.Web.UI.WebControls;
using System.Web.UI.HtmlControls;
namespace Chapter2.CodeBehindStyle
{
public partial class Default : System.Web.UI.Page
{
protected void btnComments_Click(object sender, EventArgs e)
{
LoadComments();
}
/// <summary>
/// Load all comments from the Access DB
/// </summary>
private void LoadComments()
{
string AppPath = System.AppDomain.CurrentDomain. BaseDirectory.ToString();
string sCon = @"Provider=Microsoft.JET.OLEDB.4.0; Data Source=" + AppPath + "/App_Data/Guestbook.mdb";
using (OleDbConnection cn = new OleDbConnection(sCon))
{
string sQuery = @"SELECT * FROM Guestbook order by EntryDate desc";
OleDbCommand cmd = new OleDbCommand(sQuery, cn);
OleDbDataAdapter da = new OleDbDataAdapter(cmd);
DataSet ds = new DataSet();
cn.Open();
da.Fill(ds);
rptComments.DataSource = ds;
rptComments.DataBind();
}
}
}//end class
}//end namespace

In the code above we are simply loading all guestbook entries in the LoadComments() method and binding it to a repeater (rptComments) in the code-behind partial class file.

Here is the ASPX form:

<%@ Page Language="C#" AutoEventWireup="true" CodeBehind="Default.aspx.cs" Inherits="Chapter2.CodeBehindStyle.Default" %>
<html>
<head>
<title>Chapter 2: Code-behind sample in ASP.NET</title>
</head>
<body>
<form id="form1" runat="server">
<div>
<asp:Button ID="btnComments" runat="server" Text="View All Comments" OnClick="btnComments_Click" />
<h1>Guestbook Entries</h1>
<asp:Repeater id="rptComments" runat="server">
<ItemTemplate>
Name: <%# Eval("FullName")%>
<br>
Email: <%# Eval("EmailID")%>
<br>
Website: <%# Eval("Website")%>
<br>
Dated: <%# Eval("EntryDate")%>
<br>
Comments: <%# Eval("Comments")%>
</ItemTemplate>
</asp:Repeater>
</div>
</form>
</body>
</html>

As you can see, we don't have any C# or VB.NET coding in the ASPX pages; all of the managed code is in the code-behind class. Also note that the declaration of any server side control is put in a separate designer.cs file, which is auto-generated after parsing the ASPX markup file. So we have a clean logical separation of the declarative ASPX controls placement (HTML part) and the actual managed code in the code-behind partial classes. Here is a diagrammatic representation of this 1-tier 1-layer style having 2 sub-layers in the main UI layer:

UI Layer

From the given diagram, we can see that we still have one single physical DLL, but the UI code itself is logically separated into two layers—one in the markup code and the other in the code-behind file. Note that, as explained in the beginning of this chapter, this architecture is 1-tier from the application's viewpoint, but overall it is still 3-tier if we consider the client browser as the presentation tier, and the database as the data tier. We are only focusing on the application tier, which houses the UI layer in the above examples.

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ASP.NET 3.5 Application Architecture and Design

Sample Project using Code-Behind