Question

我继承了这个网站并且存在文件下载问题。 .pdf，.doxs，.txt等文件作为映像保存在Sql中。数据列表控件与a href控件一起使用以查看/下载它但它不起作用。我意识到a href控件不适合使用，但不确定使用什么控件。

这是aspx标记：

<asp:DataList ID="DataList2" runat="server" DataSourceID="SqlDataSource2" DataKeyField="fileId">
   <ItemTemplate>
     <a href='<%# "~/UserControls/FileFetch.ashx?fileId=" + Convert.ToString(Eval("fileId")) %>' target="_blank">
       <%# Convert.ToString(Eval("fileName"))%></a>
   </ItemTemplate>
</asp:DataList>
<asp:SqlDataSource ID="SqlDataSource2" runat="server" ConnectionString="<%$ ConnectionStrings:ClubSiteDB %>"
  SelectCommand="SELECT [fileId], [fileName], [postedBy] FROM [FilesLibrary]">                
</asp:SqlDataSource>

一个名为FileFetch.ashx的帮助文件用于获取文件：

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

using System;
using System.Web;
using System.Data.SqlClient;
using System.Data;
using System.IO;

public class FileFetch : IHttpHandler
{
    const int BUFFERSIZE = 1024;

    public bool IsReusable
    {
       get
       {
           return true;
       }
    }

    public void ProcessRequest(HttpContext context)
    {
       HttpResponse response = context.Response;
       HttpRequest request = context.Request;
       response.ContentType = "response.ContentType";
       response.Cache.SetCacheability(HttpCacheability.Public);
       response.BufferOutput = false;
       writeSingleImage(Convert.ToInt32(request.QueryString["fileId"]), response.OutputStream);
       response.End();
    }

    public void writeSingleImage(int fileId, Stream output)
    {
        string cxnstr = System.Configuration.ConfigurationManager.ConnectionStrings["ClubSiteDB"].ConnectionString;
        SqlConnection connection = new SqlConnection(cxnstr);
        string query;
        query = "SELECT fileData FROM dbo.FilesLibrary where fileId=@fileId";

        SqlCommand command = new SqlCommand(query, connection);
        SqlParameter param0 = new SqlParameter("@fileId", SqlDbType.Int);
        param0.Value = fileId;
        command.Parameters.Add(param0);
        connection.Open();

        byte[] d = ((byte[])(command.ExecuteScalar()));
        output.Write(d, 0, d.Length);
        connection.Close();
   }

}

Answer 1

我将对此进行一次尝试，并说您需要将Anchor标记更改为以下内容：

<a href='<%# Page.ResolveUrl("~/UserControls/FileFetch.ashx?fileId=" + Convert.ToString(Eval("fileId"))) %>' target="_blank">

Page.ResolveUrl方法的MSDN链接为here。页面从Control继承，因此链接引用Control.ResolveUrl的原因。

我刚刚看到另一种方法是将runat="server"添加到Anchor标记，以将其转换为服务器控件。

从数据库下载文件不起作用

1 个答案: