C# TCP退出Accept阻塞的兩種方法

方法一：將偵聽套接字強行關掉，這樣會使Accept引發異常，從而達到退出阻塞的目的。

方法二：先拆除循環條件，再給監聽端口發送一條自定義命令，解析成功后，Accept自然退出阻塞。

后臺代碼：

using System;using System.Text;using System.Windows;using System.Threading;using System.Net;using System.Net.Sockets;namespace SocketBlockingInterrupt{    public partial class MainWindow : Window    {        bool bIsExecute;        TcpListener listener;//監聽套接字        SynchronizationContext synContext;        public MainWindow()        {            InitializeComponent();            synContext = SynchronizationContext.Current;            btnStop.IsEnabled = false;        }        PRivate void btnStart_Click(object sender, RoutedEventArgs e)        {            bIsExecute = true; //建立循環條件            btnStart.IsEnabled = false;            btnStop.IsEnabled = true;            //開啟監聽線程            Thread t = new Thread(new ThreadStart(ListenThread));            t.IsBackground = true;            t.Start();        }        void ListenThread()        {            ipEndPoint localEP = new IPEndPoint(IPAddress.Any, 9000);            listener = new TcpListener(localEP);            listener.Start();         //啟動監聽，非阻塞            synContext.Post(updateUI, "監聽線程：正在監聽中...");            while (bIsExecute) //循環條件            {                byte[] recvBuff = new byte[512];                //捕獲異常，強行退出Accept阻塞                try                {                    synContext.Post(updateUI, "監聽線程：Accept正在阻塞中...");                    TcpClient client = listener.AcceptTcpClient();     // 等待連接（阻塞）                    synContext.Post(updateUI, "監聽線程：收到連接請求，已退出Accept阻塞");                    int recvByte = client.Client.Receive(recvBuff);// 建立連接                    // 解析命令                    byte[] buff = new byte[recvByte];                    for (int i = 0; i < recvByte; i++ ) { buff[i] = recvBuff[i]; }                    string exitByt = Encoding.ASCII.GetString(buff);                    if (exitByt == "Exit")                    {                        synContext.Post(updateUI, "監聽線程：收到數據" + exitByt);                        break;                    }                }                catch (SocketException ex)                {                    synContext.Post(updateUI, "監聽線程：發生異常，Accept阻塞被強行退出：" + ex.Message);                    break;                }            }            synContext.Post(updateUI, "監聽線程：已成功退出監聽");        }        private void btnStop_Click(object sender, RoutedEventArgs e)        {            bIsExecute = false; //此處拆除循環條件            //方法1：直接停止監聽套接字，引發異常從而強行使Accept退出阻塞。            //---------------------------------------------            //if (listener != null)            //{            //    listener.Stop();            //}            //---------------------------------------------                        //方法2：主動發送一條數據，使Accept自然地退出阻塞。            //---------------------------------------------            TcpClient tcpClient = new TcpClient();            tcpClient.Connect("127.0.0.1",9000);            NetworkStream ns = tcpClient.GetStream();            if (ns.CanWrite)            {                Byte[] sendBytes = Encoding.ASCII.GetBytes("Exit");                ns.Write(sendBytes, 0, sendBytes.Length);                lbMsg.Items.Add("發送退出命令成功！");            }            else            {                lbMsg.Items.Add("發送退出命令失敗！");                return;            }            ns.Close();            tcpClient.Close();            //---------------------------------------------            btnStart.IsEnabled = true;            btnStop.IsEnabled = false;        }        void updateUI(object o)        {            string str = (string)o;            lbMsg.Items.Add(str);        }    }}
WPF前臺代碼：
<Window x:Class="SocketBlockingInterrupt.MainWindow"        xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"        xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"        Title="MainWindow" Height="350" Width="525">    <Grid>        <Button Content="開始偵聽" Height="23" HorizontalAlignment="Left" Margin="12,12,0,0" Name="btnStart" VerticalAlignment="Top" Width="75" Click="btnStart_Click" />        <Button Content="結束偵聽" Height="23" HorizontalAlignment="Left" Margin="108,12,0,0" Name="btnStop" VerticalAlignment="Top" Width="75" Click="btnStop_Click" />        <ListBox Height="258" HorizontalAlignment="Left" Margin="12,41,0,0" Name="lbMsg" VerticalAlignment="Top" Width="479" />    </Grid></Window>