【转】结合ashx来在DataGrid中显示从数据库中读出的图片
下面利用ashx文件可以方便实现从数据库中读取图片并显示在datagrid当中
1.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="宋体">
<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>
2.BindImage.aspx.cs
using System;
using System.Data;
using System.Drawing;
using System.Web; using System.Data.SqlClient;
namespace ShowImage
{
///
/// BindImg 的摘要说明。
///
public class BindImage: System.Web.UI.Page
{
protected System.Web.UI.WebControls.DataGrid MyDataGrid;
private void Page_Load(object sender, System.EventArgs e)
{
// 在此处放置用户代码以初始化页面
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();
}
}
}
Web 窗体设计器生成的代码
}
}
3.GetImage.ashx
<%@ WebHandler Language="C#" Class="ShowImage.GetImage" CodeBehind="GetImage.ashx.cs" %>4.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 的摘要说明。
///
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生成缩略图
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;
}
}
}
}
1.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="宋体"> <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>using System;using System.Data;using System.Drawing;using System.Web; using System.Data.SqlClient; namespace ShowImage{ /// /// BindImg 的摘要说明。 /// public class BindImage: System.Web.UI.Page { protected System.Web.UI.WebControls.DataGrid MyDataGrid; private void Page_Load(object sender, System.EventArgs e) { // 在此处放置用户代码以初始化页面 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(); } } } Web 窗体设计器生成的代码 }}<%@ WebHandler Language="C#" Class="ShowImage.GetImage" CodeBehind="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 的摘要说明。 /// 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生成缩略图 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使用了空架类库的易用的Image.GetThumbnailImage方法来把位图缩小到宽度为48像素，同时保持图象的长宽比。可以使用类似的技术来创建显示来自其他数据库图象的DataGrid。基本的思想是使用模板列来输出一个引用某个HTTP处理句柄的<img>标签，并在查询字符串中包含唯一标识图片所在的记录的信息。之后，HTTP处理句柄使用ADO.NET来获取图象数据位，并使用GDI+(图象设备接口+)来构建图象。
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