下面利用ashx文件可以方便實現從數據庫中讀取圖片並顯示在datagrid當中
//---------------------------------------BindImage.aspx ----------------------------------------
<%@ Page language="c#" Codebehind="BindImage.aspx.cs" AutoEventWireup="false" Inherits="ShowImage.BindImg" %>
<HTML>
<HEAD>
<title>BindImg</title>
</HEAD>
<body>
<form id="Form1" method="post" runat="server">
<FONT face="宋體">
<asp:DataGrid id="MyDataGrid" runat="server" AutoGenerateColumns="False" Width="632px">
<AlternatingItemStyle BackColor="Beige"></AlternatingItemStyle>
<HeaderStyle HorizontalAlign="Center"></HeaderStyle>
<Columns>
<asp:TemplateColumn HeaderText="Photo">
<ItemTemplate>
<img src='<%# "GetImage.ashx?ID="+DataBinder.Eval(Container.DataItem,"EmployeeID")%>'>
</ItemTemplate>
</asp:TemplateColumn>
<asp:BoundColumn DataField="LastName" HeaderText="Last Name"></asp:BoundColumn>
<asp:BoundColumn DataField="FirstName" HeaderText="First Name"></asp:BoundColumn>
<asp:BoundColumn DataField="title" HeaderText="Title"></asp:BoundColumn>
</Columns>
</asp:DataGrid></FONT>
</form>
</body>
</HTML>
<%@ Page language="c#" Codebehind="BindImage.aspx.cs" AutoEventWireup="false" Inherits="ShowImage.BindImage" %>
//------------------------------------BindImage.aspx.cs ---------------------------------------------
P>using System;
using System.Data;
using System.Drawing;
using System.Web; using System.Data.SqlClient;
namespace ShowImage
{
///
/// BindImg 的摘要說明。
///
public class BindImage: System.Web.UI.Page
{
protected System.Web.UI.WebControls.DataGrid MyDataGrid;
private void Page_Load(object sender, System.EventArgs e)
{
// 在此處放置用戶代碼以初始化頁面
if(!Page.IsPostBack)
{
SqlConnection conn = new SqlConnection(@"Server=shoutor/mydb;database=northwind;uid=sa;Pwd=shoutor");
try
{
conn.Open();
SqlCommand cmd = new SqlCommand("select employeeID,lastname,firstname,title from employees",conn);
SqlDataReader reader = cmd.ExecuteReader();
MyDataGrid.DataSource = reader;
MyDataGrid.DataBind();
}
finally
{
conn.Close();
}
}
}
#region Web 窗體設計器生成的代碼
override protected void OnInit(EventArgs e)
{
//
// CODEGEN: 該調用是 ASP.NET Web 窗體設計器所必需的。
//
InitializeComponent();
base.OnInit(e);
}
///
/// 設計器支持所需的方法 - 不要使用代碼編輯器修改
/// 此方法的內容。
///
private void InitializeComponent()
{
this.Load += new System.EventHandler(this.Page_Load);
}
#endregion
}
}
//-----------------------------GetImage.ashx ---------------------------------------
<%@ WebHandler Language="C#" Class="ShowImage.GetImage" CodeBehind="GetImage.ashx.cs" %>
//--------------------------------GetImage.ashx.cs----------------------------------
using System;
using System.Web;
using System.Data;
using System.Data.SqlClient;
using System.Drawing;
using System.Drawing.Imaging;
using System.IO;
namespace ShowImage
{
///
/// GetImg 的摘要說明。
///
public class GetImage : IHttpHandler
{
public void ProcessRequest(HttpContext context)
{
string id = (string)context.Request["id"];
if(id!=null)
{
MemoryStream stream = new MemoryStream();
SqlConnection conn = new SqlConnection(@"Server=;database=;uid=;Pwd=");
Bitmap bm = null;
Image image = null;
try
{
conn.Open();
SqlCommand cmd = new SqlCommand("select photo from employees where employeeid='"+id+"'",conn);
byte[] blob = (byte[])cmd.ExecuteScalar();
stream.Write (blob,78,blob.Length-78);
bm = new Bitmap(stream);
int width=48;
int height = (int)(width*((double)bm.Height/(double)bm.Width));
// GetThumbnailImage生成縮略圖
image = bm.GetThumbnailImage(width,height,null,IntPtr.Zero);
context.Response.ContentType = "image/jpeg";
image.Save(context.Response.OutputStream,ImageFormat.Jpeg);
}
finally
{
if(image!=null)
image.Dispose();
if(bm!=null)
bm.Dispose();
stream.Close();
conn.Close();
}
}
}
public bool IsReusable
{
get
{
return true;
}
}
}
}
ProcessRequest使用了空架類庫的易用的Image.GetThumbnailImage方法來把位圖縮小到寬度為48像素，同時保持圖象的長寬比。可以使用類似的技術來創建顯示來自其他數據庫圖象的DataGrid。基本的思想是使用模板列來輸出一個引用某個HTTP處理句柄的<img>標簽，並在查詢字符串中包含唯一標識圖片所在的記錄的信息。之後，HTTP處理句柄使用ADO.NET來獲取圖象數據位，並使用GDI+(圖象設備接口+)來構建圖象。
