利用HTTP处理句柄，定制DataGrid

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

 1 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
13 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    
22        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
40        }
41
42        Web 窗体设计器生成的代码#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        
52        /**//// <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
60        }
61        #endregion
62
63        private void DataGrid1_SelectedIndexChanged(object sender, System.EventArgs e)
64        {
65        
66        }
67    }
68}
69

webform1.aspx html代码：

 1 <% @ 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 < meta  content ="Microsoft Visual Studio .NET 7.1"  name =GENERATOR >
 7 < meta  content =C#  name =CODE_LANGUAGE >
 8 < meta  content =JavaScript  name =vs_defaultClientScript >
 9 < meta  content =http://schemas.microsoft.com/intellisense/ie5  name =vs_targetSchema >
10    </ 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：

 1 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
 8 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
25                try
26                {
27                    connection.Open();
28                    SqlCommand command =new SqlCommand ("SELECT Photo from Employees WHERE EmployeeID = '" + id +"'" ,connection);
29                    
30                    byte[] blob =(byte[]) command.ExecuteScalar();
31                    stream.Write (blob,78,blob.Length-78);
32                    bitmap=new Bitmap(stream);
33
34                    int width =48;
35                    int height = (int)(width*((double) bitmap.Height /(double) bitmap.Width ));
36                    image =bitmap.GetThumbnailImage(width,height,null,IntPtr.Zero );
37
38
39                    context.Response.ContentType="image/jpeg";
40                    image.Save (context.Response.OutputStream,ImageFormat.Jpeg );
41
42                 
43                }
44                finally
45                {
46                    if (image !=null)
47                        image.Dispose();
48                    if (bitmap !=null)
49                        bitmap.Dispose();
50                    stream.Close();
51                    connection.Close();
52
53                }
54            }
55        }
56
57        public bool IsReusable
58        {
59            get {return true;}
60        }
61    }
62}
63