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我编写了一段简单的代码，可以从 url 下载文件。此代码在 Windows 7 中完美运行，以良好的速度下载文件并保持显示下载进度的进度条。但是，当我从 Windows XP SP2 运行相同的代码时，它会产生一个 .NET IOException ，对我来说它为什么不起作用是没有意义的。它以相同的方式开始，正确完成第一次读取，然后在第二次尝试从流中读取时抛出以下异常：

 System.IO.IOException: Unable to read data from the transport connection: An operation on a
 socket could not be performed because the system lacked sufficient buffer space or because a
 queue was full. ---> 

 System.Net.Sockets.SocketException: An operation on a socket could not be  
 performed because the system lacked sufficient buffer space or because a queue was full
 at System.Net.Sockets.Socket.Receive(Byte[] buffer, Int32 offset, Int32 size, SocketFlags socketFlags)

 at System.Net.Sockets.NetworkStream.Read(Byte[] buffer, Int32 offset, Int32 size)
 --- End of inner exception stack trace ---
 at System.Net.ConnectStream.Read(Byte[] buffer, Int32 offset, Int32 size)
 at ServicePackChk.SrvPackChk.DownLoadServicePack(Boolean bWindowsXP)
 at ServicePackChk.SrvPackChk.CheckServicePackStatus()
 at ServicePackChk.Form1.Form1_Load(Object sender, EventArgs e)
 at System.Windows.Forms.Form.OnLoad(EventArgs e)

代码 ：

        Uri uri;

        if (bWindowsXP)
            uri = new Uri("http://download.microsoft.com/download/d/3/0/d30e32d8-418a-469d-b600-f32ce3edf42d/WindowsXP-KB936929-SP3-x86-ENU.exe");
        else
            uri = null;

        WebRequest req = WebRequest.Create(uri);
        WebResponse resp = req.GetResponse();

        ProgBarForm pform = new ProgBarForm();

        updateEvent += new SrvPackChk.UpdateDownloaded(pform.UpdateProgBar);

        Stream stream = resp.GetResponseStream();
        ArrayList alBytes = new ArrayList();
        int nLen = (int)resp.ContentLength;


        pform.DownLoadSize = nLen;

        pform.Show();

        byte[] byExe = new byte[nLen];

        bool bMoreToDownload = true;

        FileStream fs = new FileStream(System.IO.Path.GetTempPath() + "XPSP3.exe", FileMode.Create);

        MessageBox.Show("Saving File to " + System.IO.Path.GetTempPath() + "XPSP3.exe");

        while (bMoreToDownload)
        {
            Application.DoEvents();

            int nRead = 0;

            nRead = stream.Read(byExe, 0, nLen);

            nDownloaded += nRead;

            updateEvent(nDownloaded);

            if (nDownloaded == nLen)
            {
                bMoreToDownload = false;
            }

            fs.Write(byExe, 0, nRead);
            fs.Flush();

            Application.DoEvents();
        }

        stream.Close();

        fs.Close();
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1 回答 1

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您下载的文件有超过 300 兆字节，您尝试从流中一口气读取。

您最好按块读取流，例如 4MByte 块。

于 2012-05-01T17:41:50.060 回答