如何下载的MemoryStream到一个文件？(How to download memorystre

我用写作下面的示例代码和下载内存流在C＃中的文件。

MemoryStream memoryStream = new MemoryStream();
TextWriter textWriter = new StreamWriter(memoryStream);
textWriter.WriteLine("Something");           
byte[] bytesInStream = new byte[memoryStream.Length];
memoryStream.Write(bytesInStream, 0, bytesInStream.Length);
memoryStream.Close();          
Response.Clear();
Response.ContentType = "application/force-download";
Response.AddHeader("content-disposition",
                   "attachment; filename=name_you_file.xls");
Response.BinaryWrite(bytesInStream);
Response.End();

我收到以下错误：

指定参数超出有效值的范围。
参数名：偏移

可能是什么原因？

Answer 1:

在你的代码，你将数据复制到阵列中的点，在TextWriter的可能没有刷新数据。这将（）发生在你的flush（）或当您关闭它。

看看这个工程：

MemoryStream memoryStream = new MemoryStream();
TextWriter textWriter = new StreamWriter(memoryStream);
textWriter.WriteLine("Something");   
textWriter.Flush(); // added this line
byte[] bytesInStream = memoryStream.ToArray(); // simpler way of converting to array
memoryStream.Close(); 

Response.Clear();
Response.ContentType = "application/force-download";
Response.AddHeader("content-disposition", "attachment;    filename=name_you_file.xls");
Response.BinaryWrite(bytesInStream);
Response.End();

Answer 2:

您在这里逻辑做错了什么。首先，你写一些文字到MemoryStream ，然后你写一个空数组到同流。我假设你正在试图流的内容复制到bytesInStream阵列。您可以通过调用创建数组memoryStream.ToArray()

或者，可以通过直接将数据写入流，以避免阵列复制的响应输出流使用MemoryStream.CopyTo 。更换你BinaryWrite使用该调用：

 memoryStream.Position = 0;
 memoryStream.CopyTo(Response.OutputStream);

注：该流在开始明确定位，因为CopyTo将当前位置复制。

Answer 3:

OK，既然一个明显得到downvoted提供只是一个工作的例子，让我解释：

首先，你不这样做

textWriter.Flush()

并期望的TextWriter的内容已经被刷新到的MemoryStream。

然后，你不这样做

memoryStream.Position = 0

并期望从位置0将MemoryStream被“写”。

然后，你做

memoryStream.Write(bytesInStream, 0, bytesInStream.Length);

但实际上你的意思是

memoryStream.Read(bytesInStream, 0, CInt(memoryStream.Length))

你也错过了长度很长，而读操作使用一个整数，这样你就可以得到一个异常那里。

因此，这是你的代码最小修改为“工作”（我它复制到VB工程）

Imports System.Web
Imports System.Web.Services

Public Class TextHandler
    Implements System.Web.IHttpHandler

    Sub ProcessRequest(ByVal context As HttpContext) Implements IHttpHandler.ProcessRequest

        'context.Response.ContentType = "text/plain"
        'context.Response.Write("Hello World!")


        Dim memoryStream As New System.IO.MemoryStream()
        Dim textWriter As System.IO.TextWriter = New System.IO.StreamWriter(memoryStream)
        textWriter.WriteLine("Something")
        textWriter.Flush()

        memoryStream.Position = 0
        Dim bytesInStream As Byte() = New Byte(memoryStream.Length - 1) {}
        'memoryStream.Write(bytesInStream, 0, bytesInStream.Length)
        memoryStream.Read(bytesInStream, 0, CInt(memoryStream.Length))

        memoryStream.Close()
        context.Response.Clear()
        context.Response.ContentType = "application/force-download"
        context.Response.AddHeader("content-disposition", "attachment; filename=name_you_file.txt")
        context.Response.BinaryWrite(bytesInStream)
        context.Response.End()
    End Sub

    ReadOnly Property IsReusable() As Boolean Implements IHttpHandler.IsReusable
        Get
            Return False
        End Get
    End Property

End Class

然后使用

Content-Type: application/force-download

意思是

“我，web服务器，我要骗你（浏览器），这个文件是什么，所以你不会把它作为一个PDF / Word文档/ MP3 /不管，并提示用户保存神秘的文件保存到磁盘代替”。这是一个肮脏的黑客打破可怕的，当客户端没有做“保存到磁盘”。

...

最后，你不正确编码的文件名，所以如果使用非ASCII字符的文件名，它会断章取义的文件名，这是非常有趣的，如果你恰巧是中国或俄罗斯和完全ASCII字符集之外运行。

原版的

这里一个快速摘自我的ajax处理程序之一。这是VB.NET，转换时，采取了长-1后事。

Sub ProcessRequest(ByVal context As HttpContext) Implements IHttpHandler.ProcessRequest
    Dim strFileName As String = "Umzugsmitteilung.doc"
    Dim strUID As String = context.Request.QueryString("ump_uid")
    context.Response.Clear()


    'If String.IsNullOrEmpty(strUID) Or fileData Is Nothing Then
    '    context.Response.Write("<script type=""text/javascript"">alert('File does not exist !')</script>")
    '    context.Response.End()
    'End If

    context.Response.ClearContent()

    'context.Response.AddHeader("Content-Disposition", "attachment; filename=" + strFileName)
    context.Response.AddHeader("Content-Disposition", GetContentDisposition(strFileName))

    'context.Response.ContentType = "application/msword"
    context.Response.ContentType = "application/octet-stream"

    GetUmzugsMitteilung(strUID)

    context.Response.End()
End Sub ' ProcessRequest



Public Shared Sub SaveWordDocumentToOutputStream(strUID As String, doc As Aspose.Words.Document)

    Using ms As System.IO.MemoryStream = New System.IO.MemoryStream()
        CreateWordDocumentFromTemplate(strUID, doc, ms)
        ms.Position = 0

        Dim bytes As Byte() = New Byte(ms.Length - 1) {}
        ms.Read(bytes, 0, CInt(ms.Length))

        System.Web.HttpContext.Current.Response.OutputStream.Write(bytes, 0, ms.Length)
        ms.Close()
    End Using ' ms

End Sub ' SaveWordDocumentToOutputStream





    Public Shared Function StripInvalidPathChars(str As String) As String
        If str Is Nothing Then
            Return Nothing
        End If

        Dim strReturnValue As String = ""

        Dim strInvalidPathChars As New String(System.IO.Path.GetInvalidPathChars())

        Dim bIsValid As Boolean = True
        For Each cThisChar As Char In str
            bIsValid = True

            For Each cInvalid As Char In strInvalidPathChars
                If cThisChar = cInvalid Then
                    bIsValid = False
                    Exit For
                End If
            Next cInvalid

            If bIsValid Then
                strReturnValue += cThisChar
            End If
        Next cThisChar

        Return strReturnValue
    End Function ' StripInvalidPathChars


    Public Shared Function GetContentDisposition(ByVal strFileName As String) As String
        ' http://stackoverflow.com/questions/93551/how-to-encode-the-filename-parameter-of-content-disposition-header-in-http
        Dim contentDisposition As String
        strFileName = StripInvalidPathChars(strFileName)

        If System.Web.HttpContext.Current IsNot Nothing AndAlso System.Web.HttpContext.Current.Request.Browser IsNot Nothing Then
            If (System.Web.HttpContext.Current.Request.Browser.Browser = "IE" And (System.Web.HttpContext.Current.Request.Browser.Version = "7.0" Or System.Web.HttpContext.Current.Request.Browser.Version = "8.0")) Then
                contentDisposition = "attachment; filename=" + Uri.EscapeDataString(strFileName).Replace("'", Uri.HexEscape("'"c))
            ElseIf (System.Web.HttpContext.Current.Request.Browser.Browser = "Safari") Then
                contentDisposition = "attachment; filename=" + strFileName
            Else
                contentDisposition = "attachment; filename*=UTF-8''" + Uri.EscapeDataString(strFileName)
            End If
        Else
            contentDisposition = "attachment; filename*=UTF-8''" + Uri.EscapeDataString(strFileName)
        End If

        Return contentDisposition
    End Function ' GetContentDisposition

Answer 4:

您正在使用一个很长的路字符串转换为字节。
你确定，你需要的任何数据流？为什么就是不使用编码？

Response.BinaryWrite(Encoding.UTF8.GetBytes("Something"))