Question

我正在尝试在VB.NET中下载附件，但收到如下错误：

无法转换类型为＆＃39; System.String＆＃39;的对象输入＆＃39; System.Byte []＆＃39;

我的代码：

Protected Sub DownloadFile(ByVal sender As Object, ByVal e As EventArgs)

    Dim id As Integer = Integer.Parse(TryCast(sender, LinkButton).CommandArgument)
    Dim bytes As Byte()
    Dim fileName As String, contentType As String
    strQry = "select file_name, license_doc, file_type from Driver_Mas where Id=" & Val(id)

    Reader = Osql.ExecuteRead(strQry)
    While Reader.Read
        bytes = DirectCast(Reader.Item("license_doc"), Byte())            
        contentType = Reader.Item("file_type").ToString()
        fileName = Reader.Item("file_name").ToString()
        Response.Clear()
        Response.Buffer = True
        Response.Charset = ""
        Response.Cache.SetCacheability(HttpCacheability.NoCache)
        Response.ContentType = contentType
        Response.AppendHeader("Content-Disposition", "attachment; filename=" + fileName)
        Response.BinaryWrite(bytes)
        Response.Flush()
        Response.End()
    End While
End Sub

Answer 1

您需要使用Encoding.GetBytes方法从字符串中获取字节。如有必要，您可以将UTF8更改为任何其他编码

bytes = Encoding.UTF8.GetBytes(Reader.Item("license_doc"))

下载附件。无法转换类型为＆＃39; System.String＆＃39;的对象输入＆＃39; System.Byte []＆＃39;

1 个答案: