我有一个条形码扫描仪硬件设备，可以连续扫描经过的条形码，并通过它的tcpip端口发送数据。扫描仪安装在生产线上，并读取所有通过的条形码以进行验证。除了在连接时可能通过NetworkStream类发送的信息之外，没有任何信息发送到条形码扫描器。我实现了一个非常简单的接口来验证连接和接收设备发送的预期数据。显然，这段代码的问题是它只迭代了一定次数。无论循环选择如何，我都需要一个接收数据并继续接收数据的应用程序，直到我的代码选择停止关闭连接并停止接收数据。它必须始终在端口上查看来自设备的tcp ip服务器的传入数据。
public void readData()
{
int n = 1;
Byte[] data;
Int32 port = 51236;
TcpClient client = new TcpClient("192.168.0.70", port);
NetworkStream stream = client.GetStream();
String responseData = String.Empty;
try
{
while (n < 50)
{
data = new Byte[256]; //arbitrary length for now
// String to store the response ASCII representation.
// Read the first batch of the TcpServer response bytes.
Int32 bytes = stream.Read(data, 0, data.Length);
responseData = System.Text.Encoding.ASCII.GetString(data, 0, bytes);
m_upcCode = responseData;
n++;
}
}
catch (ArgumentNullException ArgEx)
{
m_upcCode = "ArgumentNullException: {0}" + ArgEx.Message.ToString();
}
catch (SocketException exSocket)
{
m_upcCode = "SocketException: {0}" + exSocket.Message.ToString();
}
}
我一直在浏览有关建立与tcp ip服务器的连接以及从服务器接收数据的大量帖子。我发现最有希望的帖子可能是Can a TCP c# client receive and send continuously/consecutively without sleep?。我只是在理解如何实现设计时遇到问题。我很高兴看到该帖子中的代码只需在表单上调用并实现，并在文本框中显示数据。接收的数据总是固定长度的12位数的条形码和a。除非传送带停止，否则数据不会停止。但是我们不希望因为线路暂停而关闭连接。 C# TCP Client listening for data还有一篇专门试图解决阅读条形码的帖子，但没有得到很多答复。
答案 0 :(得分：0)
完全取出柜台。当你执行读操作并返回零字节时，让线程暂时休眠，然后循环。
public void readData()
{
Byte[] data;
Int32 port = 51236;
TcpClient client = new TcpClient("192.168.0.70", port);
NetworkStream stream = client.GetStream();
String responseData = String.Empty;
try
{
while (true)
{
data = new Byte[256]; //arbitrary length for now
// String to store the response ASCII representation.
// Read the first batch of the TcpServer response bytes.
Int32 bytes = stream.Read(data, 0, data.Length);
if (bytes == 0){
System.Threading.Thread.Sleep(1000);
}
else {
responseData = System.Text.Encoding.ASCII.GetString(data, 0, bytes);
m_upcCode = responseData;
}
}
}
catch (ArgumentNullException ArgEx)
{
m_upcCode = "ArgumentNullException: {0}" + ArgEx.Message.ToString();
}
catch (SocketException exSocket)
{
m_upcCode = "SocketException: {0}" + exSocket.Message.ToString();
}
}
答案 1 :(得分：-1)
也许这段代码可以帮到你。 这是我为连接器（协议转换）应用程序编写的TCP服务器。它只能处理来自一个客户端的一个连接。它运行的是一个单独的线程，可以通过一些公共方法进行控制。它引发了与其他代码通信的事件。您可能需要更改某些代码（例如日志记录部分）。我希望它可以帮助你。
public class TCPServer : ITCPServer
{
private readonly IPEndPoint _ipEndPoint;
private TcpListener _tcpListener;
private TcpClient _tcpClient;
private bool _runServer;
private bool _connectToClient;
private NetworkStream _networkStream;
private volatile bool _isRunning;
public TCPServer(IPEndPoint ipEndpoint)
{
_ipEndPoint = ipEndpoint;
}
#region Properties
public bool IsRunning
{
get { return _isRunning; }
}
#endregion
#region Events
public event Action<byte[]> OnMessageReceived;
public event Action<string> OnConnectionOpened;
public event Action<string> OnConnectionClosed;
public event Action<LogLevel, string> OnLogMessage;
#endregion
#region Public Methods
public void Start()
{
_tcpListener = new TcpListener(_ipEndPoint);
_runServer = true;
_tcpListener.Start();
var thread = new Thread(RunServerEngine);
thread.Name = "TcpServer";
thread.Start();
while (!_isRunning)
{
}
var localEndpoint = (IPEndPoint)_tcpListener.LocalEndpoint;
RaiseOnLogMessage(LogLevel.Info, String.Format("Server started listening at ip address {0} on port {1}", localEndpoint.Address, localEndpoint.Port));
}
public void Stop()
{
_connectToClient = false;
_runServer = false;
}
public void SendMessage(byte[] message)
{
_networkStream.Write(message, 0, message.Length);
_networkStream.Flush();
}
public void DisconnectClient()
{
_connectToClient = false;
}
#endregion
#region Private Methods
private void RunServerEngine(Object obj)
{
try
{
_isRunning = true;
while (_runServer)
{
Thread.Sleep(250);
if (_tcpListener.Pending())
{
using (_tcpClient = _tcpListener.AcceptTcpClient())
{
var socketForClient = _tcpClient.Client;
_networkStream = new NetworkStream(socketForClient);
RaiseOnConnectionOpened((IPEndPoint)_tcpClient.Client.RemoteEndPoint);
_connectToClient = true;
while (_connectToClient)
{
if (CheckClientConnection() == false)
{
_connectToClient = false;
break;
}
if (_networkStream.DataAvailable)
{
var bytes = new Byte[1024];
_networkStream.Read(bytes, 0, 1024);
bytes = bytes.TakeWhile(b => b > 0).ToArray();
RaiseOnMessageReceived(bytes);
}
Thread.Sleep(100);
}
}
RaiseOnConnectionClosed();
}
}
RaiseOnLogMessage(LogLevel.Info, "Stopping TCP Server");
_tcpListener.Stop();
_isRunning = false;
RaiseOnLogMessage(LogLevel.Info, "TCP Server stopped");
}
catch (Exception ex)
{
RaiseOnLogMessage(LogLevel.Error, String.Format("Fatal error in TCP Server, {0}", ex.ToString()));
throw;
}
}
private bool CheckClientConnection()
{
var connected = true;
try
{
var pollResult = _tcpClient.Client.Poll(1, SelectMode.SelectRead);
var dataAvailable = _tcpClient.Client.Available;
connected = !(pollResult && _tcpClient.Client.Available == 0);
if (!connected)
{
RaiseOnLogMessage(LogLevel.Info, "Detected disconnection from client");
RaiseOnLogMessage(LogLevel.Info, String.Format("TCPServer.CheckClientConnection - connected: {0}, pollResult: {1}, dataAvailable: {2}", connected, pollResult, dataAvailable));
}
}
catch (SocketException ex)
{
RaiseOnLogMessage(LogLevel.Info, String.Format("Exception occurred in TCPServer.CheckClientConnection. Ex: {0}", ex.ToString()));
connected = false;
}
return connected;
}
private void RaiseOnMessageReceived(byte[] message)
{
if (OnMessageReceived != null)
{
try
{
OnMessageReceived(message);
}
catch (Exception ex)
{
RaiseOnLogMessage(LogLevel.Warning, ex.Message);
}
}
}
private void RaiseOnConnectionOpened(IPEndPoint remoteEndpoint)
{
if (OnConnectionOpened != null)
{
var msg = String.Format("Connected to client with ip address: {0}, port: {1}", remoteEndpoint.Address, remoteEndpoint.Port);
OnConnectionOpened(msg);
}
}
private void RaiseOnConnectionClosed()
{
if (OnConnectionClosed != null)
OnConnectionClosed("Disconnected from client");
}
private void RaiseOnLogMessage(LogLevel level, string message)
{
if (OnLogMessage != null)
OnLogMessage(level, message);
}
#endregion
}