官术网_书友最值得收藏!

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

Sample Project using Code-Behind

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.

主站蜘蛛池模板: 墨玉县| 海口市| 霞浦县| 湟中县| 祁阳县| 汽车| 嘉兴市| 谷城县| 镇原县| 无锡市| 龙州县| 阿拉善右旗| 沽源县| 吴江市| 新密市| 郸城县| 潜江市| 中江县| 怀远县| 榆中县| 葫芦岛市| 阳东县| 射阳县| 高陵县| 佳木斯市| 藁城市| 柏乡县| 津市市| 辽中县| 甘洛县| 绥阳县| 平舆县| 贵港市| 甘南县| 昌乐县| 肥乡县| 中卫市| 合作市| 乐业县| 渭源县| 定日县|