我正在尝试使用 c# 开发服务器/客户端异步套接字。我已经遵循了MSDN链接上的指南。在我的例子中，套接字服务器侦听特定的端点，许多客户端可以一次连接到服务器，客户端可以与服务器通信，服务器可以与客户端通信。假设客户端 1 和客户端 2 与服务器连接，客户端 1 可以向服务器发送消息，服务器可以发送到客户端 1，客户端 2 的情况也是如此。现在我希望客户端应该能够通过服务器相互通信。例如;客户端 2 想要与客户端 1 通信，因为客户端 2 将向服务器发送消息(此消息将包含一些预设字符;)，然后服务器将从客户端 2 接收文本，并将获取客户端 1 的处理程序并将此消息发送到客户端 1，客户端 1 将响应服务器，现在我想将客户端 1 针对该消息的响应发送到客户端 2， 但我不知道该怎么做，因为客户端 1 通过自己的处理程序与服务器进行通信，我在这里被打动了，将非常感谢帮助！！ 我的代码如下：
using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading;
using System.Threading.Tasks;
using System.Net;
using System.Net.Sockets;
namespace SocketServer
{
// State object for reading client data asynchronously
public class StateObject
{
// Client socket.
public Socket workSocket = null;
// Size of receive buffer.
public const int BufferSize = 1024;
// Receive buffer.
public byte[] buffer = new byte[BufferSize];
// Received data string.
public StringBuilder sb = new StringBuilder();
public int clientNumber;
}
public class AsyncSocketServer
{
public static ManualResetEvent allDone = new ManualResetEvent(false);
public static Dictionary<int, StateObject> Clients = new Dictionary<int, StateObject>();
public static int connectedClient = 0;
public AsyncSocketServer()
{
}
public static void startListening() {
Byte[] bytes = new Byte[1024];
int Port = 1122;
IPAddress IP = IPAddress.Parse("127.0.0.1");
IPEndPoint EP = new IPEndPoint(IP, Port);
Socket listner = new Socket(IP.AddressFamily, SocketType.Stream, ProtocolType.Tcp);
try
{
listner.Bind(EP);
listner.Listen(100);
while (true)
{
allDone.Reset();
Console.WriteLine("Waiting for the Connection......");
listner.BeginAccept(new AsyncCallback(AcceptCallBack), listner);
allDone.WaitOne();
}
}
catch(Exception e)
{
Console.WriteLine("Exception Occured ! in start listening method "+e.ToString());
}
Console.WriteLine("nPress ENTER to continue...");
Console.Read();
}
public static void AcceptCallBack(IAsyncResult ar)
{
connectedClient++;
Console.WriteLine("client number " + connectedClient);
allDone.Set();
Socket listner = (Socket) ar.AsyncState;
Socket handler = listner.EndAccept(ar);
StateObject state = new StateObject();
state.clientNumber = connectedClient;
Clients.Add(connectedClient, state);
Console.WriteLine("total clients {0}",Clients.Count());
state.workSocket = handler;
handler.BeginReceive(state.buffer, 0, StateObject.BufferSize,0,new AsyncCallback(ReadCallBack),state);
}
public static void ReadCallBack(IAsyncResult ar)
{
String content = String.Empty;
// Retrieve the state object and the handler socket
// from the asynchronous state object.
try {
StateObject state = (StateObject) ar.AsyncState;
state.sb.Clear();
Socket handler = state.workSocket;
// Read data from the client socket.
int bytesRead = handler.EndReceive(ar);
if (bytesRead > 0) {
// There might be more data, so store the data received so far.
state.sb.Append(Encoding.ASCII.GetString(
state.buffer,0,bytesRead));
// Check for end-of-file tag. If it is not there, read
// more data.
content = state.sb.ToString();
if (content.Substring(0, 3) == "cmd") {
foreach (StateObject Client in Clients.Values) {
if (Client.clientNumber == 1) {
Console.WriteLine("value is "+Client.clientNumber);
if (isClientConnected(Client.workSocket)){
Send(Client.workSocket, "did you receive my message");
//now client number 1 will response through its own handler, but i want to get response of
//client number 1 and return this response to client number 2
}
else {
string responsemsg = "client number " + Client.clientNumber + " is disconnected !";
Console.WriteLine(responsemsg);
Send(handler,responsemsg);
}
}
}
}
Console.WriteLine("Read {0} bytes from client {1} socket. n Data : {2}",
content.Length, state.clientNumber,content);
// Echo the data back to the client.
if (isClientConnected(handler))
{
Send(handler, content);
}
handler.BeginReceive(state.buffer, 0, StateObject.BufferSize, 0, new AsyncCallback(ReadCallBack), state);
}
}
catch (SocketException e)
{
//once if any client disconnected then control will come into this block
Console.WriteLine("Socket Exception Occured in Read Call Back : " + e.Message.ToString());
}
catch (Exception e)
{
//once if any client disconnected then control will come into this block
Console.WriteLine("Exception Occured in Read Call Back : " + e.Message.ToString());
}
}
private static void Send(Socket handler, String data)
{
// Convert the string data to byte data using ASCII encoding.
byte[] byteData = Encoding.ASCII.GetBytes(data);
// Begin sending the data to the remote device.
handler.BeginSend(byteData, 0, byteData.Length, 0,
new AsyncCallback(SendCallback), handler);
}
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());
}
}
public static bool isClientConnected(Socket handler){
return handler.Connected;
}
public static int Main(string[] args)
{
startListening();
return 0;
}
}
}
对于任何复杂的基于套接字的应用程序，我建议使用像 DotNetty 这样的套接字库来抽象传输层，并允许您专注于应用程序逻辑。 查看他们的SecureChat示例，它可能与您尝试实现的目标非常相似。
我提出了一个 DotNetty 服务器的快速示例，它允许您通过让客户端向服务器注册，然后让服务器在客户端之间路由消息来在客户端之间发送命令。
using System;
using System.Collections.Concurrent;
using System.Threading;
using System.Threading.Tasks;
using DotNetty.Transport.Channels;
using Newtonsoft.Json;
using System.IO;
namespace MultiClientSocketExample
{
public enum Command
{
Register = 1, // Register a new client
SendToClient = 2, // Send a message from one client to antoher
DoClientAction = 3 // Replace this with your client-to-client command
}
// Envelope for all messages handled by the server
public class Message
{
public string ClientId { get; set; }
public Command Command { get; set; }
public string Data { get; set; }
}
// Command for seding a message from one client to antoher.
// This would be serialized as JSON and stored in the 'Data' member of the Message object.
public class SendToClientCommand
{
public string DestinationClientId { get; set; } // The client to receive the message
public Command ClientCommand { get; set; } // The command for the destination client to execute
public string Data { get; set; } // The payload for the destination client
}
// An object for storing unhandled messages in a queue to be processed asynchronously
// This allows us to process messages and respond to the appropriate client,
// without having to do everything in the ChannelRead0 method and block the main thread
public class UnhandledMessage
{
private readonly Message message;
private readonly IChannelHandlerContext context;
public UnhandledMessage(Message message, IChannelHandlerContext context)
{
this.message = message;
this.context = context;
}
public Message Message => message;
public IChannelHandlerContext Context => context;
public Command Command => message.Command;
public string ClientId => message.ClientId;
public string Data => message.Data;
}
// A representation of the connected Clients on the server.
// Note: This is not the 'Client' class that would be used to communicate with the server.
public class Client
{
private readonly string clientId;
private readonly IChannelHandlerContext context;
public Client(string clientId, IChannelHandlerContext context)
{
this.clientId = clientId;
this.context = context;
}
public string ClientId => clientId;
public IChannelHandlerContext Context => context;
}
// The socket server, using DotNetty's SimpleChannelInboundHandler
// The ChannelRead0 method is called for each Message received
public class Server : SimpleChannelInboundHandler<Message>, IDisposable
{
private readonly ConcurrentDictionary<string, Client> clients;
private readonly ConcurrentQueue<UnhandledMessage> unhandledMessages;
private readonly CancellationTokenSource cancellation;
private readonly AutoResetEvent newMessage;
public Server(CancellationToken cancellation)
{
this.clients = new ConcurrentDictionary<string, Client>();
this.newMessage = new AutoResetEvent(false);
this.cancellation = CancellationTokenSource.CreateLinkedTokenSource(cancellation);
}
// The start method should be called when the server is bound to a port.
// Messages will be received, but will not be processed unless/until the Start method is called
public Task Start()
{
// Start a dedicated thread to process messages so that the ChannelRead operation does not block
return Task.Run(() =>
{
var serializer = JsonSerializer.CreateDefault(); // This will be used to deserialize the Data member of the messages
while (!cancellation.IsCancellationRequested)
{
UnhandledMessage message;
var messageEnqueued = newMessage.WaitOne(100); // Sleep until a new message arrives
while (unhandledMessages.TryDequeue(out message)) // Process each message in the queue, then sleep until new messages arrive
{
if (message != null)
{
// Note: This part could be sent to the thread pool if you want to process messages in parallel
switch (message.Command)
{
case Command.Register:
// Register a new client, or update an existing client with a new Context
var client = new Client(message.ClientId, message.Context);
clients.AddOrUpdate(message.ClientId, client, (_,__) => client);
break;
case Command.SendToClient:
Client destinationClient;
using (var reader = new JsonTextReader(new StringReader(message.Data)))
{
var sendToClientCommand = serializer.Deserialize<SendToClientCommand>(reader);
if (clients.TryGetValue(sendToClientCommand.DestinationClientId, out destinationClient))
{
var clientMessage = new Message { ClientId = message.ClientId, Command = sendToClientCommand.ClientCommand, Data = sendToClientCommand.Data };
destinationClient.Context.Channel.WriteAndFlushAsync(clientMessage);
}
}
break;
}
}
}
}
}, cancellation.Token);
}
// Receive each message from the clients and enqueue them to be procesed by the dedicated thread
protected override void ChannelRead0(IChannelHandlerContext context, Message message)
{
unhandledMessages.Enqueue(new UnhandledMessage(message, context));
newMessage.Set(); // Trigger an event so that the thread processing messages wakes up when a new message arrives
}
// Flush the channel once the Read operation has completed
public override void ChannelReadComplete(IChannelHandlerContext context)
{
context.Flush();
base.ChannelReadComplete(context);
}
// Automatically stop the message-processing thread when this object is disposed
public void Dispose()
{
cancellation.Cancel();
}
}
}
我尝试做同样的事情，也基于MSDN的相同代码 一个可能的解决方案是使用套接字列表：
List<Socket> clients = new List<Socket>();
然后，当客户端连接时，将客户端添加到列表中：
public void AcceptCallback(IAsyncResult ar)
{
// Signal the main thread to continue.
allDone.Set();
// Get the socket that handles the client request.
Socket listener = (Socket)ar.AsyncState;
Socket handler = listener.EndAccept(ar);
clients.Add(handler);
...
}
您必须知道连接的每个客户端的 id(句柄)，然后您可以向特定客户端发送一些消息：
public void SendToOne(string id,string message)
{
foreach (Socket s in clients)
{
if (s.Handle.ToString() == id)
{
Send(s, message);
}
}
}