c#基于socket编程实现简单多人聊天程序

首先直接上代码链接,欢迎修改与指正:https://github.com/yinyoupoet/chatRoomTest
代码、可运行程序、详细设计文档、使用说明等都在里面啦

然后再上图你们感受下:
这是服务器
这是同时开了两个客户端

客户端本来想做个在线列表的,就在那空出来的那块,因为时间原因做出了半成品但是还有bug,就没上传了。

下面讲一下设计思路。(如果是新手不懂下面的术语也没关系,我在代码的注释里会写的很清楚,可以先大致了解一下)
多人聊天用p2p不太好,就是用c/s模式了。服务器设置好监听套接字,绑定监听的IP地址和端口,然后一直监听该端口就行了。
客户端首先需要连接上服务器,所以设置的IP和端口(要连接的服务器的IP和端口)必须是得和服务器一样的,不然肯定连接不上。
然后客户端连接上后,服务器将其用户名与客户端的套接字绑定好,然后保存在一个Dictionary里面。以后客户端发送的消息由服务器直接向该数组中所有套接字转发即可。

代码有点长,而且是winform,所以不好放代码,本程序是用vs2013写的,必须装了.NET Fragment 4.5以上框架的windows 64位系统才能运行程序。

不过把代码放在最后,供github抽风进不去时看看,注释很详细,我也是从完全不懂抄别人的慢慢找资料学会的。只放了后台代码,界面的不好放这了,不过一般都可根据命名和截图猜得出。建议还是直接去github里面下载下来,看的更舒服。

服务器端:

using System;
using System.Collections.Generic;
using System.ComponentModel;
using System.Data;
using System.Drawing;
using System.Linq;
using System.Net;
using System.Net.Sockets;
using System.Text;
using System.Windows.Threading;
using System.Threading;
using System.Threading.Tasks;
using System.Windows.Forms;
using System.IO;
using System.Security.Cryptography;


//参考网址:  http://www.tuicool.com/articles/RBJFRn
//参考网址:  http://zhangxuefei.site/p/59

namespace chatRoomServer
{

    public partial class Form1 : Form
    {
        public Form1()
        {
            InitializeComponent();
            ipadr = IPAddress.Loopback;
        }

        //保存多个客户端的通信套接字
        public static Dictionary<String, Socket> clientList = null;
        //申明一个监听套接字 
        Socket serverSocket = null;
        //设置一个监听标记
        Boolean isListen = true;
        //开启监听的线程
        Thread thStartListen;
        //默认一个主机监听的IP
        IPAddress ipadr;
        //将endpoint设置为成员字段
        IPEndPoint endPoint;


        private void btnStart_Click(object sender, EventArgs e)
        {
            if (serverSocket == null)
            {
                try
                {
                    isListen = true;
                    clientList = new Dictionary<string, Socket>();



                    //实例监听套接字

                    //参考网址:http://blog.csdn.net/sight_/article/details/8138802
                    //int socket(int domain, int type, int protocol);
                    //  domain:   协议域,又名协议族。常用的协议族有,AF_INET、AF_INET6、AF_LOCAL(或称AF_UNIX,Unix域socket)、AF_ROUTE等等。
                    //协议族决定了socket的地址类型,在通信中必须采用对应的地址,如AF_INET决定了要用ipv4地址(32位的)与端口号(16位的)的组合、AF_UNIX决定了要用一个绝对路径名作为地址。
                    //  type:     指定socket类型,。常用的socket类型有,SOCK_STREAM、SOCK_DGRAM、SOCK_RAW、SOCK_PACKET、SOCK_SEQPACKET等等
                    //  protocol:   指定协议。常用的协议有,IPPROTO_TCP、IPPTOTO_UDP、IPPROTO_SCTP、IPPROTO_TIPC等
                    //并不是上面的type和protocol可以随意组合的,如SOCK_STREAM不可以跟IPPROTO_UDP组合。当protocol为0时,会自动选择type类型对应的默认协议
                    serverSocket = new Socket(AddressFamily.InterNetwork, SocketType.Stream, ProtocolType.Tcp);     //AddressFamily.InterNetwork代表IPV4地址,不包含IPV6   参考网址:http://bbs.csdn.net/topics/390283656?page=1

                    //端点
                    /*  在IPEndPoint类中有两个很有用的构造函数:
                        public IPEndPoint(long, int); 
                        public IPEndPoint(IPAddress, int);
                        它们的作用就是用指定的地址和端口号初始化IPEndPoint类的新实例。
                     * 参考网址:http://www.cnblogs.com/Medeor/p/3546359.html
                     */
                    //IPAddress ipadr = IPAddress.Parse("192.168.1.100");
                    //如果txtIP里面有值,就选择填入的IP作为服务器IP,不填的话就默认是本机的

                    endPoint = new IPEndPoint(ipadr, 8080);     //IPAddress.loopback是本地环回接口,其实是虚拟接口,物理不存在的  参考网址:http://baike.sogou.com/v7893363.htm?fromTitle=loopback


                    //绑定
                    //把一个地址族的特定地址给socket
                    //int bind(int sockfd, const struct sockaddr *addr, socklen_t addrlen);
                    //sockfd:   即socket描述字,它是通过socket()函数创建了,唯一标识一个socket。bind()函数就是将给这个描述字绑定一个名字。
                    //*addr:    一个const struct sockaddr *指针,指向要绑定给sockfd的协议地址。这个地址结构根据地址创建socket时的地址协议族的不同而不同
                    //addrlen:  对应的是地址的长度
                    //通常服务器在启动的时候都会绑定一个众所周知的地址(如ip地址+端口号),用于提供服务,客户就可以通过它来接连服务器;
                    //而客户端就不用指定,有系统自动分配一个端口号和自身的ip地址组合。
                    //这就是为什么通常服务器端在listen之前会调用bind(),而客户端就不会调用,而是在connect()时由系统随机生成一个。
                    //参考网址:http://blog.csdn.net/sight_/article/details/8138802

                    //但是这里的bind不是上面的bind,是.NET里面的一个bind,使 Socket 与一个本地终结点相关联。 命名空间:System.Net.Sockets  程序集:System(在 system.dll 中)
                    //给套接字绑定一个端点,其实差不多用上面的那种bind也能实现
                    //参考网站: https://msdn.microsoft.com/zh-cn/library/system.net.sockets.socket.bind(VS.80).aspx
                    //10.127.221.248
                    try
                    {
                        serverSocket.Bind(endPoint);



                        //设置最大连接数
                        //如果作为一个服务器,在调用socket()、bind()之后就会调用listen()来监听这个socket,如果客户端这时调用connect()发出连接请求,服务器端就会接收到这个请求。
                        //int listen(int sockfd, int backlog);
                        //listen函数的第一个参数即为要监听的socket描述字,第二个参数为相应socket可以排队的最大连接个数。
                        //socket()函数创建的socket默认是一个主动类型的,listen函数将socket变为被动类型的,等待客户的连接请求。
                        serverSocket.Listen(100);


                        thStartListen = new Thread(StartListen);
                        thStartListen.IsBackground = true;
                        thStartListen.Start();

                        //这里有点不一样,原文用的是  txtMsg.Dispatcher.BeginInvoke

                        /*Invoke在线程中等待Dispatcher调用指定方法,完成后继续下面的操作。
                         * BeginInvoke不必等待Dispatcher调用制定方法,直接继续下面的操作。
                         * 参考网址: https://zhidao.baidu.com/question/1175146013330422099.html?qbl=relate_question_1&word=Dispatcher.BeginInvoke%B5%C4%CF%E0%CD%AC%BA%AF%CA%FD
                         * 更好的参考网址:http://www.cnblogs.com/lsgsanxiao/p/5523282.html
                        **/
                        txtMsg.BeginInvoke(new Action(() =>
                        {
                            txtMsg.Text += "服务启动成功...
";
                        }));
                    }
                    catch (Exception eg)
                    {
                        MessageBox.Show("输入的IP地址无效,请重新输入!");
                        txtMsg.BeginInvoke(new Action(() =>
                        {
                            txtMsg.Text += "服务启动失败...
";
                        }));


                        if (serverSocket != null)
                        {
                            serverSocket.Close();
                            thStartListen.Abort();  //将监听进程关掉

                            BroadCast.PushMessage("Server has closed", "", false, clientList);
                            foreach (var socket in clientList.Values)
                            {
                                socket.Close();
                            }
                            clientList.Clear();

                            serverSocket = null;
                            isListen = false;

                        }
                    }


                }
                catch(SocketException ex)
                {
                    MessageBox.Show(ex.ToString());
                }
            }

        }



        //线程函数,封装一个建立连接的通信套接字
        private  void StartListen()
        {
            isListen = true;
            //default()只是设置为一个初始值,这里应该为null  参考网址:https://stackoverflow.com/questions/28720717/why-default-in-c-sharp-tcpclient-clientsocket-defaulttcpclient
            Socket clientSocket = default(Socket);      

            while (isListen)
            {
                try
                {
                    //参考网址: http://bbs.csdn.net/topics/30100253
                    //  int accept(int sockfd, void *addr, int *addrlen); 
                    //注意这个serverSocket,它是用来监听的套接字,当有用户连接上端口后会返回一个新的套接字也就是这里的clientSocket,sercerSocket还是在那儿继续监听的
                    //详细参考网址:http://www.360doc.com/content/13/0908/17/13253385_313070996.shtml
                    //返回值是一个新的套接字描述符,它代表的是和客户端的新的连接,这个socket相当于一个客户端的socket,包含的是客户端的ip和port
                    //但是它也继承字本地的监听套接字,因此它也有服务器的ip和port信息
                    if (serverSocket == null)   //如果服务停止,即serverSocket为空了,那就直接返回
                    {
                        return;
                    }
                    clientSocket = serverSocket.Accept();   //这个方法返回一个通信套接字,并用这个套接字进行通信,错误时返回-1并设置全局错误变量
                }
                catch (SocketException e)
                {
                    File.AppendAllText("E:\Exception.txt", e.ToString() + "
StartListen
" + DateTime.Now.ToString() + "
");
                }

                //TCP是面向字节流的
                Byte[] bytesFrom = new Byte[4096];
                String dataFromClient = null;

                if (clientSocket != null && clientSocket.Connected)
                {
                    try
                    {
                        //Socket.Receive() 参考网址:http://blog.csdn.net/cpcpc/article/details/7245420
                        //public int Receive(  byte[] buffer,  int offset,   int size,  SocketFlags socketFlags )  
                        //buffer  是byte类型的数组,存储收到的数据的位置
                        //offset  是buffer中存储所接收数据的位置
                        //size    要接收的字节数
                        //socketFlags  socketFlages值的按位组合

                        Int32 len = clientSocket.Receive(bytesFrom);    //获取客户端发来的信息,返回的就是收到的字节数,并且把收到的信息都放在bytesForm里面

                        if (len > -1)
                        {
                            String tmp = Encoding.UTF8.GetString(bytesFrom, 0, len);  //将字节流转换成字符串
                            /*try
                            {
                                dataFromClient = EncryptionAndDecryption.TripleDESDecrypting(tmp);      //数据加密传输
                            }
                            catch (Exception e)
                            {

                            }
                             catch (Exception e)
                            {

                            }*/
                            dataFromClient = tmp;
                            Int32 sublen = dataFromClient.LastIndexOf("$");
                            if (sublen > -1)
                            {
                                dataFromClient = dataFromClient.Substring(0, sublen);   //获取用户名

                                if (!clientList.ContainsKey(dataFromClient))
                                {
                                    clientList.Add(dataFromClient, clientSocket);   //如果用户名不存在,则添加用户名进去

                                    //BroadCast是下面自己定义的一个类,是用来将消息对所有用户进行推送的
                                    //PushMessage(String msg, String uName, Boolean flag, Dictionary<String, Socket> clientList)
                                    BroadCast.PushMessage(dataFromClient + "Joined", dataFromClient, false, clientList);

                                    //HandleClient也是一个自己定义的类,用来负责接收客户端发来的消息并转发给所有的客户端
                                    //StartClient(Socket inClientSocket, String clientNo, Dictionary<String, Socket> cList)
                                    HandleClient client = new HandleClient(txtMsg);

                                    client.StartClient(clientSocket, dataFromClient, clientList);

                                    txtMsg.BeginInvoke(new Action(() =>
                                    {
                                        txtMsg.Text += dataFromClient + "连接上了服务器
" + DateTime.Now + "
";
                                    }));
                                }
                                else
                                {
                                    //用户名已经存在
                                    clientSocket.Send(Encoding.UTF8.GetBytes("#" + dataFromClient + "#"));
                                }
                            }
                        }
                    }
                    catch (Exception ep)
                    {
                        File.AppendAllText("E:\Exception.txt", ep.ToString() + "
		" + DateTime.Now.ToString() + "
");
                    }



                }
            }

        }








        private void btnStop_Click(object sender, EventArgs e)
        {
            if (serverSocket != null)
            {
                serverSocket.Close();
                thStartListen.Abort();  //将监听进程关掉

                BroadCast.PushMessage("Server has closed", "", false, clientList);
                foreach (var socket in clientList.Values)
                {
                    socket.Close();
                }
                clientList.Clear();

                serverSocket = null;
                isListen = false;
                txtMsg.Text += "服务停止,断开所有客户端连接	"+DateTime.Now.ToString()+"
";
            }
        }

        private void Form1_Load(object sender, EventArgs e)
        {
            try
            {
                clientList = new Dictionary<string, Socket>();
                serverSocket = new Socket(AddressFamily.InterNetwork,SocketType.Stream,ProtocolType.Tcp);//实例,监听套接字
                //IPAddress ipadr = IPAddress.Parse("192.168.1.100");

                endPoint = new IPEndPoint(ipadr,8080);//端点
                serverSocket.Bind(endPoint);//绑定
                serverSocket.Listen(100);   //设置最大连接数
                thStartListen = new Thread(StartListen);
                thStartListen.IsBackground = true;
                thStartListen.Start();
                txtMsg.BeginInvoke(new Action(() =>
                {
                    txtMsg.Text += "服务启动成功...
";
                }
                ));
                labIPnow.BeginInvoke(new Action(() => {
                    labIPnow.Text = endPoint.Address.ToString();
                }));
            }
            catch (SocketException ep)
            {
                MessageBox.Show(ep.ToString());
            }
        }

        private void Form1_FormClosed(object sender, FormClosedEventArgs e)
        {
            if (serverSocket != null)
            {
                BroadCast.PushMessage("Server has closed", "", false, clientList);
                foreach (var socket in clientList.Values)
                {
                    socket.Close();
                }
                clientList.Clear();
                serverSocket.Close();
                serverSocket = null;
                isListen = false;
                txtMsg.Text += "服务停止
";
            }

        }

        //重置监听的IP地址
        private void btnResetIp_Click(object sender, EventArgs e)
        {

                //如果txtIP里面有值,就选择填入的IP作为服务器IP,不填的话就默认是本机的
                if (!String.IsNullOrWhiteSpace(txtIP.Text.ToString().Trim()))
                {
                    try
                    {
                        ipadr = IPAddress.Parse(txtIP.Text.ToString().Trim());
                        btnStop_Click(sender, e);
                        txtMsg.BeginInvoke(new Action(() =>
                        {
                            txtMsg.Text += "服务器重启中,请稍候...
";
                        }));

                        btnStart_Click(sender, e);


                        labIPnow.BeginInvoke(new Action(() =>
                        {
                            labIPnow.Text = endPoint.Address.ToString();
                        }));
                    }
                    catch (Exception ep)
                    {
                        MessageBox.Show("请输入正确的IP后重试");
                    }
                }
                else
                {
                    MessageBox.Show("请输入重置后的IP地址后重试!");
                }


        }

        private void btnRcv_Click(object sender, EventArgs e)
        {
            if (ipadr == IPAddress.Loopback)
            {
                MessageBox.Show("当前已经处于默认状态,无需修改");
            }
            else
            {
                ipadr = IPAddress.Loopback;
                btnStop_Click(sender, e);
                txtMsg.BeginInvoke(new Action(() =>
                {
                    txtMsg.Text += "服务器重启中,请稍候...
";
                }));
                btnStart_Click(sender, e);
                labIPnow.BeginInvoke(new Action(() =>
                {
                    labIPnow.Text = endPoint.Address.ToString();
                }));
            }
        }

        private void btnClear_Click(object sender, EventArgs e)
        {
            txtMsg.BeginInvoke(new Action(() =>
            {
                txtMsg.Text = "-----------已清屏-----------
";
            }));
        }


    }


    //该类专门负责接收客户端发来的消息,并转发给所有的客户端
    public class HandleClient
    {
        Socket clientSocket;
        String clNo;
        Dictionary<String, Socket> clientList = new Dictionary<string, Socket>();
        TextBox txtMsg;
        public HandleClient() { }
        public HandleClient(TextBox tb) 
        {
            txtMsg = tb;
        }


        public void StartClient(Socket inClientSocket, String clientNo, Dictionary<String, Socket> cList)
        {
            clientSocket = inClientSocket;
            clNo = clientNo;
            clientList = cList;

            Thread th = new Thread(Chat);
            th.IsBackground = true;
            th.Start();
        }

        private void Chat()
        {
            Byte[] bytesFromClient = new Byte[4096];
            String dataFromClient;
            String msgTemp = null;
            Byte[] bytesSend = new Byte[4096];
            Boolean isListen = true;

            while (isListen)
            {
                try
                {
                    if (clientSocket == null || !clientSocket.Connected)
                    {
                        return;
                    }
                    if (clientSocket.Available > 0)
                    {
                        Int32 len = clientSocket.Receive(bytesFromClient);
                        if (len > -1)
                        {
                            dataFromClient = Encoding.UTF8.GetString(bytesFromClient, 0, len);
                            if (!String.IsNullOrWhiteSpace(dataFromClient))
                            {
                                dataFromClient = dataFromClient.Substring(0, dataFromClient.LastIndexOf("$"));   //这里的dataFromClient是消息内容,上面的是用户名
                                if (!String.IsNullOrWhiteSpace(dataFromClient))
                                {
                                    BroadCast.PushMessage(dataFromClient, clNo, true, clientList);
                                    msgTemp = clNo + ":" + dataFromClient + "		" + DateTime.Now.ToString();
                                    String newMsg = msgTemp;
                                    File.AppendAllText("E:\MessageRecords.txt", newMsg + "
", Encoding.UTF8);
                                }
                                else
                                {
                                    isListen = false;
                                    clientList.Remove(clNo);
                                    txtMsg.BeginInvoke(new Action(() =>
                                    {
                                        txtMsg.Text += clNo+ "已断开与服务器连接
" + DateTime.Now + "
";
                                    }));
                                    BroadCast.PushMessage(clNo + "已下线
","",false,clientList);
                                    clientSocket.Close();
                                    clientSocket = null;
                                }
                            }

                        }
                    }
                }
                catch (Exception e)
                {
                    isListen = false;
                    clientList.Remove(clNo);


                    clientSocket.Close();
                    clientSocket = null;
                    File.AppendAllText("E:\Exception.txt",e.ToString()+"
Chat
"+DateTime.Now.ToString()+"
");
                }
            }

        }

    }

    //向所有客户端发送信息
    public class BroadCast
    {
        //flag是用来判断传进来的msg前面是否需要加上uName:,也就是判断是不是系统信息,是系统信息的话就设置flag为false
        public static void PushMessage(String msg, String uName, Boolean flag, Dictionary<String, Socket> clientList)
        {
            foreach (var item in clientList)
            {
                Socket brdcastSocket = (Socket)item.Value;
                String msgTemp = null;
                Byte[] castBytes = new Byte[4096];
                if (flag == true)
                {
                    msgTemp = uName + ":" + msg + "		" + DateTime.Now.ToString();
                    castBytes = Encoding.UTF8.GetBytes(msgTemp);
                }
                else
                {
                    msgTemp = msg + "		" + DateTime.Now.ToString();
                    castBytes = Encoding.UTF8.GetBytes(msgTemp);
                }
                try
                {
                    brdcastSocket.Send(castBytes);
                }
                catch (Exception e)
                {
                    brdcastSocket.Close();
                    brdcastSocket = null;
                    File.AppendAllText("E:\Exception.txt",e.ToString()+"
PushMessage
"+DateTime.Now.ToString()+"
");
                    continue;
                }
            }
        }
    }

}

客户端:

using System;
using System.Collections.Generic;
using System.ComponentModel;
using System.Data;
using System.Drawing;
using System.Linq;
using System.Net;
using System.Net.Sockets;
using System.Runtime.InteropServices;
using System.Text;
using System.Threading;
using System.Threading.Tasks;
using System.Windows.Forms;


//参考代码:http://www.tuicool.com/articles/RBJFRn
namespace chatRoomClient
{
    public partial class Form1 : Form
    {
        public Form1()
        {
            InitializeComponent();
            ipadr = IPAddress.Loopback;
        }

        Socket clientSocket = null;
        static Boolean isListen = true;
        Thread thDataFromServer;
        IPAddress ipadr;

        private void btnSend_Click(object sender, EventArgs e)
        {
            SendMessage();
        }
        private void SendMessage()
        {
            if (String.IsNullOrWhiteSpace(txtSendMsg.Text.Trim()))
            {
                MessageBox.Show("发送内容不能为空哦~");
                return;
            }
            if (clientSocket != null && clientSocket.Connected)
            {
                Byte[] bytesSend = Encoding.UTF8.GetBytes(txtSendMsg.Text + "$");
                clientSocket.Send(bytesSend);
                txtSendMsg.Text  = "";
            }
            else
            {
                MessageBox.Show("未连接服务器或者服务器已停止,请联系管理员~");
                return;
            }
        }


        //每一个连接的客户端必须设置一个唯一的用户名,在服务器端是把用户名和套接字保存在Dictionary<userName,ClientSocket>中
        private void btnConnect_Click(object sender, EventArgs e)
        {
            if (String.IsNullOrWhiteSpace(txtName.Text.Trim()))
            {
                MessageBox.Show("请设置个用户名哦亲");
                return;
            }
            if (txtName.Text.Length>=17 && txtName.Text.ToString().Trim().Substring(0, 17).Equals("Server has closed"))
            {
                MessageBox.Show("该用户名中包含敏感词,请更换用户名后重试");
                return;
            }

            if (clientSocket == null || !clientSocket.Connected)
            {
                try
                {
                    clientSocket = new Socket(AddressFamily.InterNetwork, SocketType.Stream, ProtocolType.Tcp);
                    //参考网址: https://msdn.microsoft.com/zh-cn/library/6aeby4wt.aspx
                    // Socket.BeginConnect 方法 (String, Int32, AsyncCallback, Object)
                    //开始一个对远程主机连接的异步请求
                    /* string host,     远程主机名
                     * int port,        远程主机的端口
                     * AsyncCallback requestCallback,   一个 AsyncCallback 委托,它引用连接操作完成时要调用的方法,也是一个异步的操作
                     * object state     一个用户定义对象,其中包含连接操作的相关信息。 当操作完成时,此对象会被传递给 requestCallback 委托
                     */
                    //如果txtIP里面有值,就选择填入的IP作为服务器IP,不填的话就默认是本机的
                    if (!String.IsNullOrWhiteSpace(txtIP.Text.ToString().Trim()))
                    {
                        try
                        {
                            ipadr = IPAddress.Parse(txtIP.Text.ToString().Trim());
                        }
                        catch
                        {
                            MessageBox.Show("请输入正确的IP后重试");
                            return;
                        }
                    }
                    else
                    {
                        ipadr = IPAddress.Loopback;
                    }
                    //IPAddress ipadr = IPAddress.Parse("192.168.1.100");
                    clientSocket.BeginConnect(ipadr, 8080, (args) =>
                    {
                        if (args.IsCompleted)   //判断该异步操作是否执行完毕
                        {
                            Byte[] bytesSend = new Byte[4096];
                            txtName.BeginInvoke(new Action(() =>
                            {
                                bytesSend = Encoding.UTF8.GetBytes(txtName.Text.Trim() + "$");  //用户名,这里是刚刚连接上时需要传过去
                                if (clientSocket != null && clientSocket.Connected)
                                {
                                    clientSocket.Send(bytesSend);
                                    txtName.Enabled = false;    //设置为不能再改名字了
                                    txtSendMsg.Focus();         //将焦点放在
                                    thDataFromServer = new Thread(DataFromServer);
                                    thDataFromServer.IsBackground = true;
                                    thDataFromServer.Start();
                                }
                                else
                                {
                                    MessageBox.Show("服务器已关闭");
                                }

                            }));
                            txtIP.BeginInvoke(new Action(() =>
                            {
                                if (clientSocket != null && clientSocket.Connected)
                                {
                                    txtIP.Enabled = false;
                                }
                            }));
                        }
                    },null);
                }
                catch (SocketException ex)
                {
                    MessageBox.Show(ex.ToString());
                }
            }
            else
            {
                MessageBox.Show("你已经连接上服务器了");
            }
        }

        private void ShowMsg(String msg)
        {
            txtReceiveMsg.BeginInvoke(new Action(() =>
            {
                txtReceiveMsg.Text += Environment.NewLine + msg;    // 在 Windows 环境中,C# 语言 Environment.NewLine == "
" 结果为 true
                //txtReceiveMsg.ScrollToCaret();
            }));
        }

        //获取服务器端的消息
        private void DataFromServer()
        {
            ShowMsg("Connected to the Chat Server...");
            isListen = true;
            try
            {
                while (isListen)
                {
                    Byte[] bytesFrom = new Byte[4096];
                    Int32 len = clientSocket.Receive(bytesFrom);

                    String dataFromClient = Encoding.UTF8.GetString(bytesFrom, 0, len);
                    if (!String.IsNullOrWhiteSpace(dataFromClient))
                    {
                        //如果收到服务器已经关闭的消息,那么就把客户端接口关了,免得出错,并在客户端界面上显示出来
                        if (dataFromClient.ToString().Length >=17 && dataFromClient.ToString().Substring(0, 17).Equals("Server has closed"))
                        {
                            clientSocket.Close();
                            clientSocket = null;

                            txtReceiveMsg.BeginInvoke(new Action(() =>
                            {
                                txtReceiveMsg.Text += Environment.NewLine + "服务器已关闭";
                            }));

                            txtName.BeginInvoke(new Action(() =>
                            {
                                txtName.Enabled = true;
                            }));    //重连当然可以换用户名啦

                            txtIP.BeginInvoke(new Action(() =>
                            {

                                    txtIP.Enabled = true;

                            }));

                            thDataFromServer.Abort();   //这一句必须放在最后,不然这个进程都关了后面的就不会执行了

                            return;
                        }


                        if (dataFromClient.StartsWith("#") && dataFromClient.EndsWith("#"))
                        {
                            String userName = dataFromClient.Substring(1, dataFromClient.Length - 2);
                            this.BeginInvoke(new Action(() =>
                            {
                                MessageBox.Show("用户名:[" + userName + "]已经存在,请尝试其他用户名并重试");

                            }));
                            isListen = false;

                            txtName.BeginInvoke(new Action(() =>
                            {
                                txtName.Enabled = true;
                                clientSocket.Send(Encoding.UTF8.GetBytes("$"));
                                clientSocket.Close();
                                clientSocket = null;
                            }));
                            txtIP.BeginInvoke(new Action(() =>
                            {

                                    txtIP.Enabled = true;

                            }));

                        }
                        else
                        {
                            //txtName.Enabled = false;    //当用户名唯一时才禁止再次输入用户名
                            ShowMsg(dataFromClient);
                        }
                    }
                }
            }
            catch (SocketException ex)
            {
                isListen = false;
                if (clientSocket != null && clientSocket.Connected)
                {
                    //没有在客户端关闭连接,而是给服务器发送一个消息,在服务器端关闭连接
                    //这样可以将异常的处理放到服务器。客户端关闭会让客户端和服务器都抛异常
                    clientSocket.Send(Encoding.UTF8.GetBytes("$"));
                    MessageBox.Show(ex.ToString());
                }
            }
        }

        private void Form1_Activated(object sender, EventArgs e)
        {
            txtSendMsg.Focus();
        }

        private void Form1_FormClosed(object sender, FormClosedEventArgs e)
        {
            if (clientSocket != null && clientSocket.Connected)
            {
                clientSocket.Send(Encoding.UTF8.GetBytes("$"));
            }
        }

        private void btnBreak_Click(object sender, EventArgs e)
        {
            if (clientSocket != null && clientSocket.Connected)
            {
                thDataFromServer.Abort();
                clientSocket.Send(Encoding.UTF8.GetBytes("$"));

                clientSocket.Close();
                clientSocket = null;

                txtReceiveMsg.BeginInvoke(new Action(() =>
                {
                    txtReceiveMsg.Text += Environment.NewLine + "已断开与服务器的连接";

                }));

                txtName.BeginInvoke(new Action(() =>
                {
                    txtName.Enabled = true;
                }));    //重连当然可以换用户名啦
                txtIP.BeginInvoke(new Action(() =>
                {

                       txtIP.Enabled = true;

                }));


            }
        }

    }
}



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原文地址:https://www.cnblogs.com/yinyoupoet/p/13287590.html