C# 基于服务器的客户端相互直接通信(tcp连接)

实验内容：基于服务器的客户端相互直接通信

具体要求包括：

1，Server支持多客户访问；

2，C与S之间使用TCP连接；

3，C与C之间直接通信（不是通过S传递）。

4，C与C之间直接通信既可以使用TCP，也可以使用UDP。

5，可以使用Socket，也可以使用TcpClient/UdpClient等；

【实例截图】 

【核心代码】

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

namespace SyncChatClient
{
    public partial class Client : Form
    {
        private bool isExit = false;
        private TcpClient client;
        private BinaryReader br;
        private BinaryWriter bw;

        private List<User> userList = new List<User>();
        private TcpListener myListener;
        IPAddress localAddress;
        private static int myport;

        public Client()
        {
            InitializeComponent();
            Random r = new Random((int)DateTime.Now.Ticks);
            textBoxUserName.Text = "User"   r.Next(100, 999);
            listBoxOnline.HorizontalScrollbar = true;

            //---------------------c-c----------------------------------
            IPAddress[] addrIP = Dns.GetHostAddresses(Dns.GetHostName());
            localAddress = addrIP[0];

            while (true)
            {
                myport = r.Next(2049, 8888);
                try
                {
                    myListener = new TcpListener(localAddress, myport);
                    break;
                }
                catch
                {
                    //如果端口不可用
                }
            }
            myListener.Start();
            Thread myThread = new Thread(ListenClientConnect);
            myThread.IsBackground=true;
            myThread.Start();
        }

        //---------------------c-c----------------------------------
        private void ListenClientConnect()   
        {
            TcpClient newClient = null;
            while (true)
            {
                try
                {
                    newClient = myListener.AcceptTcpClient();
                }
                catch
                {
                    break;
                }
                User user = new User(newClient);
                Thread threadReceive = new Thread(ServerReceive);
                threadReceive.Start(user);
                threadReceive.IsBackground = true;
            }
        }

        //---------------------c-c----------------------------------
        private void ServerReceive(Object userState)    //客户端充当server的接收方法
        {
            User user = (User)userState ;//////////////////////////////////////////
            TcpClient client = user.client;
            while (isExit == false)
            {
                string receiveString = null;
                try
                {
                    receiveString = user.br.ReadString();
                    AddTalkMessage(receiveString);
                }
                catch
                {
                    if (isExit == false)
                    {
                        user.Close();
                        AddTalkMessage("接收信息失败");
                    }
                    break;
                }
            }
            user.Close();
        }

        private void buttonConnect_Click(object sender, EventArgs e)
        {
            buttonConnect.Enabled = false;
            try
            {
                client = new TcpClient(Dns.GetHostName(), 51888);
                AddTalkMessage("连接成功");
                NetworkStream networkStream = client.GetStream();
                br = new BinaryReader(networkStream);
                bw = new BinaryWriter(networkStream);
                SendMessage("Login,"   textBoxUserName.Text   ","   localAddress   ","   myport);
                Thread threadReceive = new Thread(new ThreadStart(ReceiveData));
                threadReceive.IsBackground = true;
                threadReceive.Start();
            }
            catch
            {
                AddTalkMessage("连接失败");
                buttonConnect.Enabled = true;
                return;
            }
            AddOnline("Server");           //添加在线者——Server
        }

        private void ReceiveData()    //客户端是client的接收方法
        {
            string receiveString = null;
            while (isExit == false)
            {
                try
                {
                    receiveString = br.ReadString();
                }
                catch
                {
                    if (isExit == false)
                    {
                        MessageBox.Show("与服务器失去联系。");
                    }
                    break;
                }
                string[] splitString = receiveString.Split(',');
                string command = splitString[0].ToLower();

                switch (command)
                {
                    case "login":
                        AddOnline(receiveString);
                        break;
                    case "logout":
                        RemoveUserName(splitString[1]);
                        break;
                    case "talk":
                        AddTalkMessage(splitString[1]   "对我说:" receiveString.Substring(splitString[0].Length   splitString[1].Length   2));
                        break;
                    default:
                        AddTalkMessage("什么意思啊："   receiveString);
                        break;
                }
            }
            Application.Exit();
        }

        private void SendMessage(string message)
        {
            try
            {
                bw.Write(message);
                bw.Flush();
            }
            catch
            {
                AddTalkMessage("发送失败！");
            }
        }

        private delegate void MessageDelegate(string message);

        private void AddTalkMessage(string message)
        {
            if (richTextBoxTalkInfo.InvokeRequired)
            {
                MessageDelegate d = new MessageDelegate(AddTalkMessage);
                richTextBoxTalkInfo.Invoke(d, new object[] { message });////////////
            }
            else
            {
                richTextBoxTalkInfo.AppendText(message   Environment.NewLine);
                richTextBoxTalkInfo.ScrollToCaret();
            }
        }

        private delegate void AddOnlineDelegate(string message);

        private void AddOnline(string message)  //把新用户添加道listBox并储存在userList中（保存ip端口）
        {
            if (message == "Server")
            {
                if (listBoxOnline.InvokeRequired)
                {
                    AddOnlineDelegate d = new AddOnlineDelegate(ToAddOnline);
                    listBoxOnline.Invoke(d, message);
                }
                else
                {
                    ToAddOnline(message);
                }
                User u = new User("Server", Dns.GetHostName(), 51888);
                userList.Add(u);
                return;
            }

            string[] splitString = message.Split(',');
            int port1;

            if (listBoxOnline.InvokeRequired)
            {
                AddOnlineDelegate d = new AddOnlineDelegate(ToAddOnline);
                listBoxOnline.Invoke(d, splitString[1]);
            }
            else
            {
                ToAddOnline(splitString[1]);
            }
            port1 = int.Parse(splitString[3]);
            User user = new User(splitString[1], splitString[2], port1);
            userList.Add(user);           
        }

        private void ToAddOnline(string message)
        {

            listBoxOnline.Items.Add(message);
            listBoxOnline.SelectedIndex = listBoxOnline.Items.Count - 1;
            listBoxOnline.ClearSelected();
        }

        private delegate void RemoveUserNameDelegate(string userName);

        private void RemoveUserName(string userName)
        {
            if (listBoxOnline.InvokeRequired)
            {
                RemoveUserNameDelegate d = RemoveUserName;
                listBoxOnline.Invoke(d, userName);
            }
            else
            {
                listBoxOnline.Items.Remove(userName);
                listBoxOnline.SelectedIndex = listBoxOnline.Items.Count - 1;
                listBoxOnline.ClearSelected();
            }
        }

        private void buttonSend_Click(object sender, EventArgs e)
        {
            if (listBoxOnline.SelectedIndex != -1)
            {
                SendMessage("Talk,"   listBoxOnline.SelectedItem   ","   textBoxSend.Text);
                AddTalkMessage("我对"   listBoxOnline.SelectedItem   "说："   textBoxSend.Text);
                textBoxSend.Clear();
            }
            else
            {
                MessageBox.Show("请先在[当前在线]中选择一个对话者");
            }
        }

        private void Client_FormClosing(object sender, FormClosingEventArgs e)
        {
            if (client != null)
            {
                SendMessage("Logout,"   textBoxUserName.Text);
                isExit = true;
                br.Close();
                bw.Close();
                client.Close();
            }
        }

        private void Client_KeyPress(object sender, KeyPressEventArgs e)
        {
            if (e.KeyChar == (Char)Keys.Return)
            {
                buttonSend.PerformClick();
            }
        }

        private void buttonTcpSend_Click(object sender, EventArgs e)
        {
            User myUser;
            if (listBoxOnline.SelectedIndex != -1)
            {
                for(int i = 0; i < listBoxOnline.SelectedItems.Count; i  )
                {
                    foreach(User u in userList)
                    {
                        if (u.userName.Equals("Server"))
                        {
                            //
                        }
                        else if (u.userName.Equals(listBoxOnline.SelectedItems[i].ToString()))
                        {
                            try
                            {
                                IPAddress ip = IPAddress.Parse(u.ip);
                                ///IPEndPoint iep = new IPEndPoint(ip, u.port);
                                
                                //TcpClient myClient = new TcpClient();
                                //myClient.Connect(iep);       //connect一直出错，ip没问题，奇怪

                                 TcpClient myClient = new TcpClient(Dns.GetHostName(), u.port);
                                myUser = new User(myClient);
                                myUser.bw.Write(textBoxUserName.Text   "向我发来TCP消息："   textBoxSend.Text);
                            }
                            catch
                            {
                                AddTalkMessage("发送失败");
                            }
                        }
                    }
                    AddTalkMessage("向"   listBoxOnline.SelectedItem   "发送TCP消息："   textBoxSend.Text);
                }
                textBoxSend.Clear();
            }
            else
            {
                MessageBox.Show("请先在[当前在线]中选择一个对话者");
            }
        }
    }
}