使用GridView绑定图片的方法，不需要在服务器端生成图片

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。


<%@ WebHandler Language="C#" Class="GetPicture" %>




using System;


using System.Web;


using System.IO;


using System.Data.SqlClient;






public class GetPicture : IHttpHandler ...{






public void ProcessRequest (HttpContext context) ...{


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


context.Response.Cache.SetCacheability(HttpCacheability.Public);


context.Response.BufferOutput = false;




Stream stream = null;




if (context.Request.QueryString["PhotoID"] != null &&


context.Request.QueryString["PhotoID"] != "")




...{


string photoId = context.Request.QueryString["PhotoID"];


stream = GetPhoto(photoId);


}


else


return;




const int buffersize = 1024 * 16;


byte[] buffer = new byte[buffersize];


if (stream == null || stream.Length < 1)


return;


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(string fileTypeID)...{


SqlConnection myConnection = new SqlConnection("Integrated Security=SSPI;Initial Catalog=WebWindows;Data Source=guosong");


SqlCommand myCommand = myConnection.CreateCommand();


myCommand.CommandText = "GetFileTypeIcon";


myCommand.CommandType = System.Data.CommandType.StoredProcedure;




myCommand.Parameters.Add(new SqlParameter("@fileTypeID", fileTypeID));


myConnection.Open();


object result = myCommand.ExecuteScalar();






try...{


return new MemoryStream((byte[])result);


}




catch (ArgumentNullException e)...{


return null;


}




finally...{


myConnection.Close();


}


}








public bool IsReusable ...{




get ...{


return false;


}


}




}

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