c#:发送文件，混合成功文件和损坏文件

Question

我在互联网上进行了一些研究后编写了该代码，以通过同一网络中的计算机发送文件。但是，有时它会发送损坏或质量低下的文件(如果文件是图片)。你能检查一下吗？注意:我只想发送 10MB 大小的文件。

Server

class Server
{
    IPEndPoint end;
    Socket sock;

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

    public static string path;
    public static string MsgCurrent = "Stopped";

    public void StartServer()
    {
        try
        {
            MsgCurrent = "Starting...";
            sock.Listen(100);
            MsgCurrent = "Works and looks for files";
            Socket clientSock = sock.Accept();
            byte[] clientData = new byte[1024 * 1024 * 10]; //count per byte
            int receivedByteLen = clientSock.Receive(clientData);
            MsgCurrent = "Receiving file ...";
            int fNameLen = BitConverter.ToInt32(clientData, 0);
            string fName = Encoding.ASCII.GetString(clientData, 4, fNameLen);
            BinaryWriter write = new BinaryWriter(File.Open(path + "/" + fName, FileMode.Append));
            write.Write(clientData, 4 + fNameLen, receivedByteLen - 4 - fNameLen);
            MsgCurrent = "Saving file....";
            write.Close();
            clientSock.Close();
            MsgCurrent = "The file was received";
        }
        catch
        {
            MsgCurrent = "Error, the file was not received";
        }
    }
}

Client

 class Client
{
    public static string ipsendf;//added
    public static string MsgCurrent = "Idle";
    public static void SendFile(string fName)
    {
        try
        {
            IPAddress ip = IPAddress.Parse(ipsendf); //127.0.0.1 in "" as string
            IPEndPoint end = new IPEndPoint(ip, 5656);
            Socket sock = new Socket(AddressFamily.InterNetwork, SocketType.Stream, ProtocolType.IP);

            string path = "";
            fName = fName.Replace("\\", "/");
            while (fName.IndexOf("/") > -1)
            {
                path += fName.Substring(0, fName.IndexOf("/") + 1);
                fName = fName.Substring(fName.IndexOf("/") + 1);
            }
            byte[] fNameByte = Encoding.ASCII.GetBytes(fName);
            if (fNameByte.Length > 10 * 1024 * 1024) //count per byte
            {
                //MsgCurrent = "File is greater than 850 kb";
                MsgCurrent = "File is greater than 10MB";
                return;
            }
            MsgCurrent = "Buffering...";
            byte[] fileData = File.ReadAllBytes(path + fName);
            byte[] clientData = new byte[4 + fNameByte.Length + fileData.Length];
            byte[] fNameLen = BitConverter.GetBytes(fNameByte.Length);
            fNameLen.CopyTo(clientData, 0);
            fNameByte.CopyTo(clientData, 4);
            fileData.CopyTo(clientData, 4 + fNameByte.Length);
            MsgCurrent = "Connecting to server ...";
            sock.Connect(end);
            MsgCurrent = "File sending ...";
            sock.Send(clientData);

            MsgCurrent = "Disconnecting...";
            sock.Close();
            MsgCurrent = "The file was sent ..";
        }
        catch (Exception ex)
        {
            //do nothing
        }
    }
}

Answer 1

套接字的默认接收大小为 8,192 字节 (for reference)。因此，从您的代码看来，您只是在服务器上读取消息的前 8,192 个字节。

您可以增加该缓冲区大小以匹配您分配的 10MB clientData 缓冲区的大小，例如，在 .Accept() 之后和 接收()..

clientSock.ReceiveBufferSize = 1024 * 1024 * 10;

或者，通过检查是否还有任何内容需要读取并继续填充本地缓冲区来分 block 接收。不过，您可能会在本地网络上处理潜在的大量消息，但一般来说，分 block 是正常的处理方式。

此外，您在服务器中写入文件时使用了 FileMode.Append，而我认为您需要 FileMode.Create。否则，如果您两次发送同一个文件，您将得到一个 20MB 的文件，而不是 10MB 的文件。