Question

对于我的项目，我试图在客户端中截取屏幕截图并通过套接字将其发送到服务器。我用一个循环来截取，直到手动停止。但是虽然拍摄截图很好，但是在发送一些图像后只变成主图像的一半而一些图像已经满了的客户端：
我正在截取这个截图

bmpScreenshot = new Bitmap(Screen.PrimaryScreen.Bounds.Width, Screen.PrimaryScreen.Bounds.Height, PixelFormat.Format32bppArgb);
gfxScreenshot = Graphics.FromImage(bmpScreenshot);
gfxScreenshot.CopyFromScreen(Screen.PrimaryScreen.Bounds.X, Screen.PrimaryScreen.Bounds.Y, 0, 0, Screen.PrimaryScreen.Bounds.Size, CopyPixelOperation.SourceCopy);
bmpScreenshot.Save(path + i + ".png");
ClientService.SendFile(path + i + ".png");
i++;

，SendFile方法是

public static void SendFile(string fileName)
        {
            try
            {
                IPAddress[] ipAddress = Dns.GetHostAddresses("localhost");
                IPEndPoint ipEnd = new IPEndPoint(ipAddress[0], 5656);
                Socket clientSock = new Socket(AddressFamily.InterNetwork, SocketType.Stream, ProtocolType.IP);

                string filePath = "";

                fileName = fileName.Replace("\\", "/");
                while (fileName.IndexOf("/") > -1)
                {
                    filePath += fileName.Substring(0, fileName.IndexOf("/") + 1);
                    fileName = fileName.Substring(fileName.IndexOf("/") + 1);
                }

                byte[] fileNameByte = Encoding.ASCII.GetBytes(fileName);
                if (fileNameByte.Length > 600 * 1024)
                {
                    showMsg = "File size is more than 600kb, please try with small file.";
                    return;
                }

                byte[] fileData = File.ReadAllBytes(filePath + fileName);
                byte[] clientData = new byte[4 + fileNameByte.Length + fileData.Length];
                byte[] fileNameLen = BitConverter.GetBytes(fileNameByte.Length);

                fileNameLen.CopyTo(clientData, 0);
                fileNameByte.CopyTo(clientData, 4);
                fileData.CopyTo(clientData, 4 + fileNameByte.Length);

                clientSock.Connect(ipEnd);
                clientSock.Send(clientData);
                clientSock.Close();

            }
            catch (Exception ex)
            {
                if (ex.Message == "No connection could be made because the target machine actively refused it")
                    showMsg = "File Sending fail. Because server is not running.";
                else
                    showMsg = "File Sending fail." + ex.Message;
            }
        }

服务器

IPEndPoint ipEnd;
    Socket sock;
    public ServerService()
    {
        ipEnd = new IPEndPoint(IPAddress.Any, 5656);
        sock = new Socket(AddressFamily.InterNetwork, SocketType.Stream, ProtocolType.IP);
        sock.Bind(ipEnd);
    }

    public static string receivedPath;
    internal void StartServer()
    {
        try
        {
            sock.Listen(100);

            Socket clientSock = sock.Accept();

            byte[] clientData = new byte[1024 * 5000];

            int receivedBytesLen = clientSock.Receive(clientData);

            int fileNameLen = BitConverter.ToInt32(clientData, 0);
            string fileName = Encoding.ASCII.GetString(clientData, 4, fileNameLen);

            BinaryWriter bWrite = new BinaryWriter(File.Open(receivedPath + "/" + fileName, FileMode.Append)); ;
            bWrite.Write(clientData, 4 + fileNameLen, receivedBytesLen - 4 - fileNameLen);

            bWrite.Close();
            clientSock.Close();
        }
        catch (Exception ex)
        {
            ShowMsg = "Something is wrong." + ex.Message;
        }
    }

我该如何解决这个问题？

Answer 1

Receive仅保证（其中之一）：

至少返回1个字节
发出EOF信号（非正字节）
发出错误信号

仅拨打Receive一次是不够的。您需要在循环中将其称为，直到：

您已阅读所有想要的数据

你得到了EOF

您收到错误

在你的情况下，我建议你想：

准确读取4个字节（可能需要循环）以获取名称长度n

然后准确读取n个字节以读取名称

然后阅读，直到您获得EOF（来自Receive的非阳性结果）

另外：您可能希望使用基于Stream的API来进行文件访问（包括读取和写入），而不是File.ReadAllBytes或BinaryWriter。

读取完全 n字节的情况类似于：

public void ReceiveExactly(Socket socket, byte[] buffer, int offset, int count) { int read; while(count > 0 && (read = socket.Receive(buffer, offset, count, SocketFlags.None)) > 0) { offset += read; count -= read; } if(count != 0) throw new EndOfStreamException(); }

通过套接字发送数据是不完整的

1 个答案: