大文件的下载（分批下载）

最新推荐文章于 2024-04-25 11:07:15 发布

原创最新推荐文章于 2024-04-25 11:07:15 发布 · 1.2k 阅读

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CC 4.0 BY-SA版权

文章标签：

#buffer #exception #integer #string #byte

本文介绍了一种在ASP.NET中实现文件下载的方法，通过解析请求中的文件名参数，读取指定路径下的文件并将其发送给客户端进行下载。文中特别关注了如何处理中文文件名的乱码问题。

可以在超链接处，链向此页，传递文件地址（filename），在load事件里面用到下面代码

Try

        '在此处放置初始化页的用户代码
        Dim strFileName As String = Request.QueryString("FileName")
            Dim toDownload As System.IO.FileInfo = New System.IO.FileInfo(Server.UrlDecode(strFileName))
            Const ChunkSize As Long = 10000'一次取多少字节
            Dim buffer(ChunkSize) As Byte

            Response.Clear()
            Dim iStream As System.IO.FileStream = System.IO.File.OpenRead(strFileName)
            Dim dataLengthToRead As Long = iStream.Length
            Dim tempfileName As String

tempfileName = HttpUtility.UrlEncode(toDownload.Name)'改变中文文件名乱码问题

            Response.ContentType = "application/octet-stream"
            Response.AddHeader("Content-Disposition", _
         "attachment; filename=" & tempfileName)
            While dataLengthToRead > 0 AndAlso Response.IsClientConnected
                Dim lengthRead As Integer = _
                    iStream.Read(buffer, 0, ChunkSize)'读取
                Response.OutputStream.Write(buffer, 0, lengthRead)'写到头里面
                Response.Flush()
                dataLengthToRead = dataLengthToRead - lengthRead
            End While
            Response.Close()

        Catch ex As Exception
            Response.Close()
        End Try