我正在使用 Microsoft 提供的异步示例编写我的第一个 TCP 服务器。
https://msdn.microsoft.com/en-us/library/fx6588te(v=vs.110).aspx
示例中的所有内容均有效。我将其扩展为一个简单的聊天程序。但是我在执行这个程序的步骤时遇到了麻烦(可能是因为它的异步性质)。收到消息后,它会回显给客户端并关闭套接字。我看不到它返回到哪里重新打开套接字。
public static void StartListening() {
// Data buffer for incoming data.
byte[] bytes = new Byte[1024];
// Establish the local endpoint for the socket.
// The DNS name of the computer
// running the listener is "host.contoso.com".
IPHostEntry ipHostInfo = Dns.Resolve(Dns.GetHostName());
IPAddress ipAddress = ipHostInfo.AddressList[0];
IPEndPoint localEndPoint = new IPEndPoint(ipAddress, 11000);
// Create a TCP/IP socket.
Socket listener = new Socket(AddressFamily.InterNetwork,
SocketType.Stream, ProtocolType.Tcp );
// Bind the socket to the local endpoint and listen for incoming connections.
try {
listener.Bind(localEndPoint);
listener.Listen(100);
while (true) {
// Set the event to nonsignaled state.
allDone.Reset();
// Start an asynchronous socket to listen for connections.
Console.WriteLine("Waiting for a connection...");
listener.BeginAccept(
new AsyncCallback(AcceptCallback),
listener );
// Wait until a connection is made before continuing.
allDone.WaitOne();
}
} catch (Exception e) {
Console.WriteLine(e.ToString());
}
Console.WriteLine("\nPress ENTER to continue...");
Console.Read();
}
private static void SendCallback(IAsyncResult ar) {
try {
// Retrieve the socket from the state object.
Socket handler = (Socket) ar.AsyncState;
// Complete sending the data to the remote device.
int bytesSent = handler.EndSend(ar);
Console.WriteLine("Sent {0} bytes to client.", bytesSent);
handler.Shutdown(SocketShutdown.Both);
handler.Close();
} catch (Exception e) {
Console.WriteLine(e.ToString());
}
}
另外,socket一直开着不是很正常吗?
最佳答案
When a message is received, it echoes back to the client and closes the socket. I do not see where it goes back to re-open the socket.
那是因为它没有。通信完成,服务器接收、发送回复并完成该连接。它只是继续等待监听套接字上的新连接。你有一段时间(真的)。您将在接听电话中继续等待新的传入连接。您将为每个新客户端获得一个新套接字。
Also, is it not normal to leave the socket open
是的,监听套接字保持打开状态。它保持打开状态以继续使用 accept 接收新连接
可以在这里找到使用异步和等待编写回显服务器的更好方法:Using .Net 4.5 Async Feature for Socket Programming
关于用于简单聊天的 C# TCP 服务器,我们在Stack Overflow上找到一个类似的问题: https://stackoverflow.com/questions/31895500/