Question

我必须使用TCP通信在项目中集成2个系统 - 开发了自定义协议。

通过协议发送的消息如下所示：

MsgLength - 10 positions (in chars, not bytes)
MessageType - 20 positions
Message Number - 9 positions
Timestamp - 19 positions
version - 2 positions
Body - variable (depending on first field)

我正在研究Socket编程，但我想知道等待完整的msg到达的最佳方法是什么。可能我需要将字节转换为剩余的字符数。因为套接字API仅适用于字节。

欢迎所有提示，代码示例，博客文章： - ）

编辑：这是我的第一个版本的代码，我使用的是Async方法，因为多个客户端可以同时连接。

  private static void Listen()
        {
            while (true)
            {
                //TcpClient client = _listener.AcceptTcpClient();
                allDone.Reset();
                _listener.BeginAcceptTcpClient(new AsyncCallback(AcceptCallback), _listener);
                allDone.WaitOne();
            }
        }


public static void AcceptCallback(IAsyncResult ar)
        {
            // Signal the main thread to continue.
            allDone.Set();

            // Get the socket that handles the client request.
            //TcpListener listener = (TcpListener)ar.AsyncState;
            TcpClient handler = _listener.EndAcceptTcpClient(ar);

            // Create the state object.
            StateObject state = new StateObject();
            state.client = handler;

            handler.GetStream().BeginRead(state.buffer, 0, StateObject.BufferSize, new AsyncCallback(ReadCallback), state);

        }

public static void ReadCallback(IAsyncResult ar)
        {
            String content = String.Empty;
            Encoding enc = Encoding.GetEncoding("ISO-8859-1");

            // Retrieve the state object and the handler socket
            // from the asynchronous state object.
            StateObject state = (StateObject)ar.AsyncState;
            TcpClient handler = state.client;

               int bytesRead = handler.GetStream().EndRead(ar);
        state.TotalHeaderBytesRead += bytesRead;

            if (bytesRead == 60)
            {
                string header = enc.GetString(state.buffer);
                Header h = HeaderParser.Parse(header);
                //todo read the body

                byte[] bodyBuffer = new byte[((HeaderPlaPo)h).Length - 60];
                state.buffer = bodyBuffer;
                handler.GetStream().BeginRead(state.buffer, 0, bodyBuffer.Length, new AsyncCallback(ReadBodyCallback), state);
                Logger.Log(string.Format("received header {0}", header), System.Diagnostics.TraceLevel.Info);
            }
            else
            {
                // Not all data of header received. Get more.
                handler.GetStream().BeginRead(state.buffer, 0, StateObject.BufferSize - state.TotalHeaderBytesRead, new AsyncCallback(ReadHeaderCallback), state);
            }
        }



public static void ReadBodyCallback(IAsyncResult ar)
        {
            Encoding enc = Encoding.GetEncoding("ISO-8859-1");

            // Retrieve the state object and the handler socket
            // from the asynchronous state object.
            StateObject state = (StateObject)ar.AsyncState;
            TcpClient handler = state.client;

            int bytesRead = handler.GetStream().EndRead(ar);
 int bytesRead = handler.GetStream().EndRead(ar);
        state.TotalBodyBytesRead += bytesRead;

        if (state.buffer.Length == state.TotalBodyBytesRead)

{ // todo我们收到了所有 string body = enc.GetString（state.buffer）; Logger.Log（string.Format（“received body {0}”，body），System.Diagnostics.TraceLevel.Info）; } 其他 { handler.GetStream（）。BeginRead（state.buffer，bytesRead，state.buffer.Length - state.TotalBodyBytesRead，ReadBodyCallback，state）; } }

公共类StateObject { //客户端套接字 public TcpClient client = null; //接收缓冲区的大小。 public static int BufferSize = 60; //接收缓冲区。 public byte [] buffer = new byte [BufferSize]; //收到数据字符串 public StringBuilder sb = new StringBuilder（）; //头 public Header标题; 公共身体; public Int32 TotalBodyBytesRead; public Int32 TotalHeaderBytesRead; }

此代码适用于发送数据并关闭连接的客户端，但是当使用连接的客户端多次发送时，数据不会被读取 - ＆gt;我应该在读完整个身体后关闭连接吗？

Answer 1

您没有提到您使用的语言，我用Java提供示例，如果您需要其他语言，请告诉我。无论如何，你需要在一次关闭中读取60（10 + 20 + 9 + 19 + 2）个字节。将10个第一个字节（字符）转换为整数，然后将该字节数读入byte []数组。

例如：

try
{
    byte[] buffer = new byte[60];
    mySocket.getInputStream().read(buffer, 0, 60);
    String header = buffer.toString();
    int length = Integer.parseInt(header.substring(0, 9));
    byte[] body = new byte[length];
    mySocket.getInputStream().read(body, 0, length);
}
catch (Exception e)
{
   e.printStackTrace();
}

编辑：改为C＃

 byte[] buffer = new byte[60];
 mySocket.Receive(buffer, 60, SocketFlags.None);
 // You should ckeck this, UTF7 or UTF8 or UNICODE, etc
 string header = Encoding.UTF7.GetString(buffer, 0, 60);
 int length = Convert.ToInt32(header.Substring(0, 10));
 byte[] body = new byte[length];
 int offset=0;
 // Keep reading the socket until all bytes has been received
 while (length > 0) 
 {
     int ret=mySocket.Receive(body, offset, length, SocketFlags.None);
     if (ret > 0) 
     {
        offset += ret;
        length -= ret;
     }
     else 
        if (ret == 0) 
        {
            // peer has close the socket
        }
        else
        {
           // there is an error in the socket.
        }

  }

等到完整的消息到达

1 个答案: