GridView中显示数据库里的图片

GridView中显示数据库里的图片

很多人开始有这个疑问，GridView控件中的ImageField没有DataField属性，那么如何才能绑定到SQL Server中的Image Field？自从DynamicImage控件从beta2中消失后，这就成了个问题。但是，ASP.NET2.0随之也给我们带来了另外一种解决方案，那就是方便地利用HttpHandler(.ashx)动态显示数据库中的图片，这点在VS2005中提供了PersonalWebSite等模版中已经给出方案：通过ashx动态获取数据库中的某条图片数据，然后在GridView等控件的自定义模版中安置一个Image控件，并设置Image控件的ImageUrl属性为类似 XXX.ashx?photoId=1 即可显示图片。

下面为Handler.ashx的代码：

<%@ WebHandler Language="C#" Class="Handler" %>using System;using System.Data;using System.Data.SqlClient;using System.IO;using System.Web;using System.Configuration;public class Handler : IHttpHandler ...{        public bool IsReusable ...{        get ...{            return true;        }    }    public void ProcessRequest(HttpContext context) ...{        // Set up the response settings        context.Response.ContentType = "image/jpeg";        context.Response.Cache.SetCacheability(HttpCacheability.Public);        context.Response.BufferOutput = false;        int photoId = -1;        Stream stream = null;        if (context.Request.QueryString["PhotoID"] != null &&            context.Request.QueryString["PhotoID"] != "") ...{            photoId = Convert.ToInt32(context.Request.QueryString["PhotoID"]);            stream = GetPhoto(photoId);        }        const int buffersize = 1024 * 16;        byte[] buffer = new byte[buffersize];        int count = stream.Read(buffer, 0, buffersize);        while (count > 0) ...{            context.Response.OutputStream.Write(buffer, 0, count);            count = stream.Read(buffer, 0, buffersize);        }    }    public Stream GetPhoto(int photoId) ...{        SqlConnection myConnection = new SqlConnection(            ConfigurationManager.ConnectionStrings["Personal"].ConnectionString);        SqlCommand myCommand = new SqlCommand            ("SELECT [BytesOriginal] FROM [Photos] WHERE [PhotoID]=@PhotoID",            myConnection);        myCommand.CommandType = CommandType.Text;        myCommand.Parameters.Add(new SqlParameter("@PhotoID", photoId));        myConnection.Open();        object result = myCommand.ExecuteScalar();                try ...{            return new MemoryStream((byte[])result);        }        catch (ArgumentNullException e) ...{            return null;        }        finally ...{            myConnection.Close();        }    }}

然后在GridView中自定义模版列：

<asp:TemplateField>    <ItemTemplate>        <asp:Image ID="Image1" runat="server"        ImageUrl='<%# "Handler.ashx?PhotoID=" + Eval("PhotoID") %>' />    </ItemTemplate></asp:TemplateField>

这样即可在GridView中动态显示数据库中image类型图片数据了。其实VS2005自带的Stater Kit很有用的，另外，还有其他几个Club Web Site Starter Kit等，都可以在asp.net上载过来看看。