利用HTTP处理句柄，定制DataGrid

Posted on 2005-07-10 16:27 如是如是阅读(482) 评论(0) 编辑收藏举报

1、显示数据库中的图片；
2、利用global.asax的Session_Start来记录登陆者信息；

global.asax.cs 代码：

protected void Session_Start(Object sender, EventArgs e)

{

SqlConnection connection =new SqlConnection("user id=sa;data source=localhost;persist security info=True;initial catalog=NetManager;password=xiayc");

/*SQLCom,Str_IpAddr,Str_Brow,Str_Option*/

string strBrow,strIpAddr,strOption;

strIpAddr=Request.UserHostAddress ;

if (Request.UserAgent.IndexOf("MSIE")> -1 )

{

strBrow="Internet Explore"+Request.Browser.Version ;

}

else

{

strBrow=Request.Browser.Browser + Request.Browser.Version;

}

if (Request.UserAgent.IndexOf("Windows NT 5.2")> -1)

{

strOption = "Windows 2003 ";

}

else

{

if (Request.UserAgent.IndexOf("Windows NT 5.1")> -1)

{

strOption = "Windows XP ";

}

else

{

if (Request.UserAgent.IndexOf("Windows NT 5.0")> -1)

{

strOption ="Windows 2000 ";

}

else

{

strOption = Request.Browser.Platform;

}

DateTime datetime=new DateTime() ;

datetime =DateTime.UtcNow;

datetime = DateTime.Now;

string s =datetime.ToString ("d");

datetime = DateTime.Parse(s);

}

webform1.aspx.cs代码

25-38行为添加代码

using System;
2

using System.Collections;
3

using System.ComponentModel;
4

using System.Data;
5

using System.Drawing;
6

using System.Web;
7

using System.Web.SessionState;
8

using System.Web.UI;
9

using System.Web.UI.WebControls;
10

using System.Web.UI.HtmlControls;
11

using System.Data.SqlClient;
12

namespace WebApplication1
14

{
15

/// <summary>
16

/// WebForm1 的摘要说明。
17

/// </summary>
18

public class WebForm1 : System.Web.UI.Page
19

{
20

protected System.Web.UI.WebControls.DataGrid DataGrid1;
21

private void Page_Load(object sender, System.EventArgs e)
23

{
24

// 在此处放置用户代码以初始化页面
25

if (!IsPostBack){
26

SqlConnection connection = new SqlConnection("user id=sa;data source=localhost;persist security info=True;initial catalog=Northwind;password=xiayc");
27

try
28

{
29

connection.Open();
30

SqlCommand command = new SqlCommand("select EmployeeID,LastName,FirstName,Title FROM Employees",connection);
31

SqlDataReader reader = command.ExecuteReader();
32

DataGrid1.DataSource =reader;
33

DataGrid1.DataBind ();
34

}
35

finally{
36

connection.Close ();
37

}
38

}
39

}
41

#region Web 窗体设计器生成的代码
43

override protected void OnInit(EventArgs e)
44

{
45

//
46

// CODEGEN: 该调用是 ASP.NET Web 窗体设计器所必需的。
47

//
48

InitializeComponent();
49

base.OnInit(e);
50

}
51

/// <summary>
53

/// 设计器支持所需的方法 - 不要使用代码编辑器修改
54

/// 此方法的内容。
55

/// </summary>
56

private void InitializeComponent()
57

{
58

this.Load += new System.EventHandler(this.Page_Load);
59

}
61

#endregion
62

private void DataGrid1_SelectedIndexChanged(object sender, System.EventArgs e)
64

{
65

}
67

}
68

}
69

webform1.aspx html代码：

<%@ Page language="c#" Codebehind="WebForm1.aspx.cs" AutoEventWireup="false" Inherits="WebApplication1.WebForm1" %>
2

<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.0 Transitional//EN" >
3

<HTML>
4

<HEAD>
5

<title>WebForm1</title>
6

</HEAD>
11

<body MS_POSITIONING="GridLayout">
12

<form id=Form1 method=post runat="server"><FONT face=宋体><asp:datagrid id=DataGrid1 style="Z-INDEX: 101; LEFT: 56px; POSITION: absolute; TOP: 48px" runat="server" Width="328px" Height="192px" AutoGenerateColumns="False">
13

<Columns>
14

<asp:TemplateColumn HeaderText="照片">
15

<ItemTemplate>
16

<img src='<%# "ImageGrabber.ashx?id=" + DataBinder.Eval(Container.DataItem,"EmployeeID") %>' border="0">
17

</ItemTemplate>
18

</asp:TemplateColumn>
19

<asp:BoundColumn DataField="LastName" HeaderText="Last Name"></asp:BoundColumn>
20

<asp:BoundColumn DataField="FirstName" HeaderText="First Name"></asp:BoundColumn>
21

</Columns>
22

</asp:datagrid></FONT></form>
23

</body>
24

</HTML>
25

注意 14行-17行为DataGrid的模板行，该模板行输出一个典型的<img>标签
<img src='ImageGrabber.ashx?id=1'>

ImageGrabber.ashx是一个HTTP处理句柄。当被调用时，它ProcessRequest方法从查询字符串中截获雇员ID,
并使用它执行自己的数据库查询。这次查询获取相应记录的Photo域，利用它创建一个位图，并把位图流作为JPEG传递给客户端。

ImageGrabber.ashx代码：
仅一行：
<%@ WebHandler language="c#" Class="WebApplication1.ImageGrabber" Codebehind="ImageGrabber.ashx.cs" %>

ImageGrabber.ashx.cs代码：

using System;
2

using System.IO;
3

using System.Web;
4

using System.Drawing;
5

using System.Drawing.Imaging ;
6

using System.Data.SqlClient;
7

namespace WebApplication1
9

{
10

/// <summary>
11

/// ImageGrabber 的摘要说明。
12

/// </summary>
13

public class ImageGrabber:IHttpHandler
14

{
15

public void ProcessRequest(HttpContext context)
16

{
17

string id = (string) context.Request["id"];
18

if (id !=null)
19

{
20

MemoryStream stream =new MemoryStream() ;
21

SqlConnection connection = new SqlConnection ("user id=sa;data source=localhost;persist security info=True;initial catalog=Northwind;password=xiayc");
22

Bitmap bitmap=null;
23

Image image=null;
24

try
26

{
27

connection.Open();
28

SqlCommand command =new SqlCommand ("SELECT Photo from Employees WHERE EmployeeID = '" + id +"'" ,connection);
29

byte[] blob =(byte[]) command.ExecuteScalar();
31

stream.Write (blob,78,blob.Length-78);
32

bitmap=new Bitmap(stream);
33

int width =48;
35

int height = (int)(width*((double) bitmap.Height /(double) bitmap.Width ));
36

image =bitmap.GetThumbnailImage(width,height,null,IntPtr.Zero );
37

context.Response.ContentType="image/jpeg";
40

image.Save (context.Response.OutputStream,ImageFormat.Jpeg );
41

}
44

finally
45

{
46

if (image !=null)
47

image.Dispose();
48

if (bitmap !=null)
49

bitmap.Dispose();
50

stream.Close();
51

connection.Close();
52

}
54

}
55

}
56

public bool IsReusable
58

{
59

get {return true;}
60

}
61

}
62

}
63

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利用HTTP处理句柄，定制DataGrid