异步示例客户端套接字循环接收

Question

我想循环接收来自服务器的新消息。但是当我使用下面的代码时，它会在 while 循环中的 receiveDone 处停止。而且它没有收到来自服务器的任何消息。如何更改以下代码或编写新代码，接收消息并在屏幕上弹出消息。

// State object for receiving data from remote device.  
public class StateObject {  
    // Client socket.  
    public Socket workSocket = null;  
    // Size of receive buffer.  
    public const int BufferSize = 256;  
    // Receive buffer.  
    public byte[] buffer = new byte[BufferSize];  
    // Received data string.  
    public StringBuilder sb = new StringBuilder();  
}  

public class AsynchronousClient {  
    // The port number for the remote device.  
    private const int port = 1200;  

    // ManualResetEvent instances signal completion.  
    private static ManualResetEvent connectDone =   
        new ManualResetEvent(false);  
    private static ManualResetEvent sendDone =   
        new ManualResetEvent(false);  
    private static ManualResetEvent receiveDone =   
        new ManualResetEvent(false);  

    // The response from the remote device.  
    private static String response = String.Empty;  

    private static void StartClient() {  
        // Connect to a remote device.  
        try {  
            // Establish the remote endpoint for the socket.    
            IPAddress ipAddress = IPAddress.Parse("127.0.0.1"); 
            IPEndPoint remoteEP = new IPEndPoint(ipAddress, port);  

            // Create a TCP/IP socket.  
            Socket client = new Socket(AddressFamily.InterNetwork,  
                SocketType.Stream, ProtocolType.Tcp);  

            // Connect to the remote endpoint.  
            client.BeginConnect( remoteEP,   
                new AsyncCallback(ConnectCallback), client);  
            connectDone.WaitOne();  

            // Send data to the remote device.  
            Send(client,"HELLO");  
            sendDone.WaitOne();

            while(true)
            {
                Receive(client);
                receiveDone.WaitOne();

                if(!string.IsNullOrWhiteSpace(response))
                    Console.WriteLine(response);
            }

            // Release the socket.  
            client.Shutdown(SocketShutdown.Both);  
            client.Close();  
        } catch (Exception e) {  
            Console.WriteLine(e.ToString());  
        }  
    }  

    private static void ConnectCallback(IAsyncResult ar) {  
            // Retrieve the socket from the state object.  
            Socket client = (Socket) ar.AsyncState;  

            // Complete the connection.  
            client.EndConnect(ar);  

            Console.WriteLine("Socket connected to {0}",  
                client.RemoteEndPoint.ToString());  

            // Signal that the connection has been made.  
            connectDone.Set();  
    }  

    private static void Receive(Socket client) {  
            // Create the state object.  
            StateObject state = new StateObject();  
            state.workSocket = client;  

            // Begin receiving the data from the remote device.  
            client.BeginReceive( state.buffer, 0, StateObject.BufferSize, 0,  
                new AsyncCallback(ReceiveCallback), state);  
    }  

    private static void ReceiveCallback(IAsyncResult ar) {  
            // Retrieve the state object and the client socket   
            // from the asynchronous state object.  
            StateObject state = (StateObject) ar.AsyncState;  
            Socket client = state.workSocket;  

            // Read data from the remote device.  
            int bytesRead = client.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));  

                // Get the rest of the data.  
                client.BeginReceive(state.buffer,0,StateObject.BufferSize,0,  
                    new AsyncCallback(ReceiveCallback), state);  
            } 
            else
            {  
                // All the data has arrived; put it in response.  
                if (state.sb.Length > 1) {  
                    response = state.sb.ToString();
                }

                // Signal that all bytes have been received.  
                receiveDone.Set();  
            }  
    }  

    private static void Send(Socket client, 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.  
        client.BeginSend(byteData, 0, byteData.Length, 0,  
            new AsyncCallback(SendCallback), client);  
    }  

    private static void SendCallback(IAsyncResult ar) {  
            // Retrieve the socket from the state object.  
            Socket client = (Socket) ar.AsyncState;  

            // Complete sending the data to the remote device.  
            int bytesSent = client.EndSend(ar);  
            Console.WriteLine("Sent {0} bytes to server.", bytesSent);  

            // Signal that all bytes have been sent.  
            sendDone.Set();  
    }  

    public static int Main(String[] args) {  
        StartClient();  
        return 0;  
    }  
}  

以上代码来自msdn。我仔细阅读了网站上的所有内容，但没有答案。

Answer 1

您遇到异常并退出程序。尝试以下修复：

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Net;
using System.Net.Sockets;
using System.Threading;


namespace ConsoleApplication48
{
    class Program
    {
        public class StateObject {  
            // Client socket.  
            public Socket workSocket = null;  
            // Size of receive buffer.  
            public const int BufferSize = 256;  
            // Receive buffer.  
            public byte[] buffer = new byte[BufferSize];  
            // Received data string.  
            public StringBuilder sb = new StringBuilder(); 
        }


        public class AsynchronousClient
        {
            // The port number for the remote device.  
            private const int port = 1200;

            // ManualResetEvent instances signal completion.  
            private static ManualResetEvent connectDone =
                new ManualResetEvent(false);
            private static ManualResetEvent sendDone =
                new ManualResetEvent(false);
            private static ManualResetEvent receiveDone =
                new ManualResetEvent(false);

            // The response from the remote device.  
            private static String response = String.Empty;

            private static void StartClient()
            {
                // Connect to a remote device.  
                try
                {
                    string LocalHostName = Dns.GetHostName();
                    IPHostEntry LocalHostIPEntry = Dns.GetHostEntry(LocalHostName); ;

                    IPAddress ipAddress = LocalHostIPEntry.AddressList.Where(x => !x.IsIPv6LinkLocal).FirstOrDefault();
                    IPEndPoint remoteEP = new IPEndPoint(ipAddress, port);

                    // Create a TCP/IP socket.  
                    Socket client = new Socket(ipAddress.AddressFamily,
                        SocketType.Stream, ProtocolType.Tcp);

                    // Connect to the remote endpoint.  
                    client.BeginConnect(remoteEP,
                        new AsyncCallback(ConnectCallback), client);
                    connectDone.WaitOne();

                    // Send data to the remote device.  
                    Send(client, "HELLO");
                    sendDone.WaitOne();

                    while (true)
                    {
                        Receive(client);
                        receiveDone.WaitOne();

                        if (!string.IsNullOrWhiteSpace(response))
                            Console.WriteLine(response);
                    }

                    // Release the socket.  
                    client.Shutdown(SocketShutdown.Both);
                    client.Close();
                }
                catch (Exception e)
                {
                    Console.WriteLine(e.ToString());
                }
            }

            private static void ConnectCallback(IAsyncResult ar)
            {
                // Retrieve the socket from the state object.  
                Socket client = (Socket)ar.AsyncState;

                // Complete the connection.  
                client.EndConnect(ar);

                Console.WriteLine("Socket connected to {0}",
                    client.RemoteEndPoint.ToString());

                // Signal that the connection has been made.  
                connectDone.Set();
            }

            private static void Receive(Socket client)
            {
                // Create the state object.  
                StateObject state = new StateObject();
                state.workSocket = client;

                // Begin receiving the data from the remote device.  
                client.BeginReceive(state.buffer, 0, StateObject.BufferSize, 0,
                    new AsyncCallback(ReceiveCallback), state);
            }

            private static void ReceiveCallback(IAsyncResult ar)
            {
                // Retrieve the state object and the client socket   
                // from the asynchronous state object.  
                StateObject state = (StateObject)ar.AsyncState;
                Socket client = state.workSocket;

                // Read data from the remote device.  
                int bytesRead = client.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));

                    Send(client, "HELLO");

                    // Get the rest of the data.  
                    client.BeginReceive(state.buffer, 0, StateObject.BufferSize, 0,
                        new AsyncCallback(ReceiveCallback), state);
                }
                else
                {
                    // All the data has arrived; put it in response.  
                    if (state.sb.Length > 1)
                    {
                        response = state.sb.ToString();
                    }

                    // Signal that all bytes have been received.  
                    receiveDone.Set();
                }
            }

            private static void Send(Socket client, 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.  
                client.BeginSend(byteData, 0, byteData.Length, 0,
                    new AsyncCallback(SendCallback), client);
            }

            private static void SendCallback(IAsyncResult ar)
            {
                // Retrieve the socket from the state object.  
                Socket client = (Socket)ar.AsyncState;

                // Complete sending the data to the remote device.  
                int bytesSent = client.EndSend(ar);
                Console.WriteLine("Sent {0} bytes to server.", bytesSent);

                // Signal that all bytes have been sent.  
                sendDone.Set();
            }
            public static void AcceptCallback(IAsyncResult ar) {  
                // Signal the main thread to continue.  

                // Get the socket that handles the client request.  
                TcpListener  listener = (TcpListener) ar.AsyncState;  
                Socket handler = listener.Server.EndAccept(ar);  

                // Create the state object.  
                StateObject state = new StateObject();  
                state.workSocket = handler;  
                handler.BeginReceive( state.buffer, 0, StateObject.BufferSize, 0,  
                    new AsyncCallback(ListenerReadCallback), state);  
            }  

            public static void ListenerReadCallback(IAsyncResult ar) {  
                String content = String.Empty;  

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

                // Read data from the client socket.   
                int bytesRead = handler.EndReceive(ar);  

                if (bytesRead > 0) {  

                        handler.BeginSend(state.buffer, 0, bytesRead, 0,  
                           new AsyncCallback(ListenerSendCallback), handler);  
                } 
                // Not all data received. Get more.  
                handler.BeginReceive(state.buffer, 0, StateObject.BufferSize, 0,  
                new AsyncCallback(ListenerReadCallback), state);    
            }
            private static void ListenerSendCallback(IAsyncResult ar) {
                Socket handler = (Socket)ar.AsyncState; 
                int bytesSent = handler.EndSend(ar);  
            }
            static void Main(string[] args)
            {
                TcpListener listener = new TcpListener(IPAddress.Any, 1200);
                listener.Start();
                listener.Server.BeginAccept(   
                    new AsyncCallback(AcceptCallback),  
                    listener );
                StartClient();

            }
        }
    }

}