# winform实现一个服务端和多个客户端进行通信

        参看此链接        http://www.cnblogs.com/longwu/archive/2011/08/25/2153636.html

        在上述代码的基础上进行了修改，包括一些捕获异常以及按钮的应用，扩充了一个listbox确保服务端可以选择和不同的客户端进行通信。

服务器代码：

using System;
using System.Collections.Generic;
using System.ComponentModel;
using System.Data;
using System.Drawing;
using System.Linq;
using System.Text;
using System.Windows.Forms;
using System.Threading;
using System.Net.Sockets;
using System.Net;
using System.Collections;
namespace chat1
{
        
    public partial class Form1 : Form
    {
        public Form1()
        {
            InitializeComponent();
            StartPosition = FormStartPosition.CenterScreen;

            //关闭对文本框的非线程操作检查
            TextBox.CheckForIllegalCrossThreadCalls = false;
        }
        string RemoteEndPoint;     //客户端的网络结点
        Thread threadwatch = null;//负责监听客户端的线程
        Socket socketwatch = null;//负责监听客户端的套接字

        //创建一个和客户端通信的套接字
        Dictionary<string, Socket> dic = new Dictionary<string, Socket> { };   //定义一个集合，存储客户端信息

        
        private void button1_Click(object sender, EventArgs e)
        {
            this.button1.Enabled = false;
            //定义一个套接字用于监听客户端发来的消息，包含三个参数（IP4寻址协议，流式连接，Tcp协议）
            socketwatch = new Socket(AddressFamily.InterNetwork,SocketType.Stream,ProtocolType.Tcp);

            //服务端发送信息需要一个IP地址和端口号
            IPAddress address = IPAddress.Parse(textBox1.Text.Trim());//获取文本框输入的IP地址
            //将IP地址和端口号绑定到网络节点point上
            IPEndPoint point = new IPEndPoint(address,int.Parse(textBox2.Text.Trim()));//获取文本框上输入的端口号
            //此端口专门用来监听的
            //监听绑定的网络节点
            socketwatch.Bind(point);
            //将套接字的监听队列长度限制为20
            socketwatch.Listen(20);            
            //创建一个监听线程
            threadwatch = new Thread(watchconnecting);             
            //将窗体线程设置为与后台同步，随着主线程结束而结束
            threadwatch.IsBackground = true;   
           //启动线程   
            threadwatch.Start();   
           //启动线程后 textBox3文本框显示相应提示
           textBox3.AppendText("开始监听客户端传来的信息!" + "\r\n");          
        }


        void OnlineList_Disp(string Info)
        {
            listBoxOnlineList.Items.Add(Info);   //在线列表中显示连接的客户端套接字
        }

       
        //监听客户端发来的请求
        private void watchconnecting()
        {
            Socket connection = null;
            while (true)  //持续不断监听客户端发来的请求   
            {
                try  
                {   
                    connection = socketwatch.Accept();  
                }   
                catch (Exception ex)   
                {  
                    textBox3.AppendText(ex.Message); //提示套接字监听异常   
                    break;   
                 }
                //获取客户端的IP和端口号
                IPAddress clientIP = (connection.RemoteEndPoint as IPEndPoint).Address;
                int clientPort = (connection.RemoteEndPoint as IPEndPoint).Port;

                //让客户显示"连接成功的"的信息
                string sendmsg = "连接服务端成功！\r\n" + "本地IP:" + clientIP + "，本地端口" + clientPort.ToString();
                byte[] arrSendMsg = Encoding.UTF8.GetBytes(sendmsg); 
                connection.Send(arrSendMsg);

                RemoteEndPoint = connection.RemoteEndPoint.ToString(); //客户端网络结点号
                textBox3.AppendText("成功与" + RemoteEndPoint + "客户端建立连接！\t\n");     //显示与客户端连接情况
                dic.Add(RemoteEndPoint, connection);    //添加客户端信息
                OnlineList_Disp(RemoteEndPoint);    //显示在线客户端              
                //IPEndPoint netpoint = new IPEndPoint(clientIP,clientPort);                
                IPEndPoint netpoint = connection.RemoteEndPoint as IPEndPoint;                
                //创建一个通信线程    
                ParameterizedThreadStart pts = new ParameterizedThreadStart(recv);
                Thread thread = new Thread(pts);   
                thread.IsBackground = true;//设置为后台线程，随着主线程退出而退出   
                //启动线程   
                thread.Start(connection);   
            }   
        }

  
        ///   
        /// 接收客户端发来的信息    
        ///   
        ///客户端套接字对象  
        private void recv(object socketclientpara)
        {            
            Socket socketServer = socketclientpara as Socket;
            while (true)   
            {   
                //创建一个内存缓冲区 其大小为1024*1024字节  即1M   
                byte[] arrServerRecMsg = new byte[1024 * 1024];   
                //将接收到的信息存入到内存缓冲区,并返回其字节数组的长度  
                try
                {
                    int length = socketServer.Receive(arrServerRecMsg);

                    //将机器接受到的字节数组转换为人可以读懂的字符串   
                    string strSRecMsg = Encoding.UTF8.GetString(arrServerRecMsg, 0, length);                    
                    //将发送的字符串信息附加到文本框txtMsg上   
                    textBox3.AppendText("客户端:" + socketServer.RemoteEndPoint+",time:" + GetCurrentTime() + "\r\n" + strSRecMsg + "\r\n\n");
                }
                catch (Exception ex)
                {
                    textBox3.AppendText("客户端"+socketServer.RemoteEndPoint+"已经中断连接"+"\r\n"); //提示套接字监听异常 
                    listBoxOnlineList.Items.Remove(socketServer.RemoteEndPoint.ToString());//从listbox中移除断开连接的客户端
                    socketServer.Close();//关闭之前accept出来的和客户端进行通信的套接字
                    break;   
                }
            }          
        }


        ///    
        /// 获取当前系统时间的方法   
        ///    
        /// 当前时间   
        private DateTime GetCurrentTime()   
        {   
            DateTime currentTime = new DateTime();   
            currentTime = DateTime.Now;   
            return currentTime;   
        }


        //发送信息到客户端 
        private void button2_Click(object sender, EventArgs e)
        {
            string sendMsg = textBox4.Text.Trim();  //要发送的信息
            byte[] bytes = System.Text.Encoding.UTF8.GetBytes(sendMsg);   //将要发送的信息转化为字节数组，因为Socket发送数据时是以字节的形式发送的

            if (listBoxOnlineList.SelectedIndex == -1)
            {
                MessageBox.Show("请选择要发送的客户端！", "提示", MessageBoxButtons.OK, MessageBoxIcon.Stop);
            }
            else
            {
                string selectClient = listBoxOnlineList.Text;  //选择要发送的客户端
                dic[selectClient].Send(bytes);   //发送数据
                textBox4.Clear();
                textBox3.AppendText(label4.Text + GetCurrentTime() + "\r\n" + sendMsg + "\r\n");   
            }                   
        }

          
        //快捷键 Enter 发送信息 
       private void textBox4_KeyDown(object sender, KeyEventArgs e)
        {
            //如果用户按下了Enter键   
            if (e.KeyCode == Keys.Enter)
            {
                string sendMsg = textBox4.Text.Trim();  //要发送的信息
                byte[] bytes = System.Text.Encoding.UTF8.GetBytes(sendMsg); 
                if (listBoxOnlineList.SelectedIndex == -1)
                {
                    MessageBox.Show("请选择要发送的客户端！", "提示", MessageBoxButtons.OK, MessageBoxIcon.Stop);
                }
                else
                {

                    string selectClient = listBoxOnlineList.Text;  //选择要发送的客户端
                    dic[selectClient].Send(bytes);   //发送数据
                    textBox4.Clear();
                    textBox3.AppendText(label4.Text + GetCurrentTime() + "\r\n" + sendMsg + "\r\n");

                }
            }
        }


        private void Form1_Load(object sender, EventArgs e)
        {
        }

        private void Form1_FormClosing(object sender, FormClosingEventArgs e)
        {
            DialogResult result = MessageBox.Show("是否退出？选否,最小化到托盘", "操作提示", MessageBoxButtons.YesNoCancel, MessageBoxIcon.Question);
            if (result == DialogResult.Yes)
            {
                this.Dispose();
            }
            else if (result == DialogResult.Cancel)
            {
                e.Cancel = true;
            }
            else
            {
                e.Cancel = true;
                this.WindowState = FormWindowState.Minimized;
                this.Visible = false;
                this.notifyIcon1.Visible = true;
                this.ShowInTaskbar = false;
            }
        }

        private void notifyIcon1_MouseDoubleClick(object sender, MouseEventArgs e)
        {
            base.Visible = true;
            this.notifyIcon1.Visible = false;
            this.ShowInTaskbar = true;
            //base.Show();
            base.WindowState = FormWindowState.Normal;
        } 
    }
}

 客户端的代码：

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


namespace chat2
{
    public partial class Form1 : Form
    {
        public Form1()
        {
            InitializeComponent();
            StartPosition = FormStartPosition.CenterScreen;
            //关闭对文本框的非法线程操作检查
            TextBox.CheckForIllegalCrossThreadCalls = false;
        }

        //创建 1个客户端套接字 和1个负责监听服务端请求的线程
        Thread threadclient = null;
        Socket socketclient = null;
        List<IPEndPoint> mlist =new List<IPEndPoint>();
        private void button1_Click(object sender, EventArgs e)
        {
            //SocketException exception;
            this.button1.Enabled = false;
            //定义一个套接字监听
            socketclient = new Socket(AddressFamily.InterNetwork,SocketType.Stream,ProtocolType.Tcp);

            //获取文本框中的IP地址
            IPAddress address = IPAddress.Parse(textBox1.Text.Trim());

            //将获取的IP地址和端口号绑定在网络节点上
            IPEndPoint point = new IPEndPoint(address,int.Parse(textBox2.Text.Trim()));

            try
            {
                //客户端套接字连接到网络节点上，用的是Connect
                socketclient.Connect(point);
            }
            catch (Exception )
            {
                //MessageBox.
                MessageBox.Show("连接失败\r\n");
                this.button1.Enabled = true;
                return;
            }
            
            threadclient=new Thread(recv);

            threadclient.IsBackground=true;

            threadclient.Start();
        }

        
        
        // 接收服务端发来信息的方法  
        private void recv()//
        {
            int x = 0;
            while (true)//持续监听服务端发来的消息
            {
                try
                {
                    //定义一个1M的内存缓冲区，用于临时性存储接收到的消息
                    byte[] arrRecvmsg = new byte[1024 * 1024];

                    //将客户端套接字接收到的数据存入内存缓冲区，并获取长度
                    int length = socketclient.Receive(arrRecvmsg);

                    //将套接字获取到的字符数组转换为人可以看懂的字符串
                    string strRevMsg = Encoding.UTF8.GetString(arrRecvmsg, 0, length);
                    if (x == 1)
                    {
                        textBox3.AppendText("服务器:" + GetCurrentTime() + "\r\n" + strRevMsg + "\r\n\n");

                    }
                    else
                    {

                        textBox3.AppendText(strRevMsg + "\r\n\n");
                        x = 1;
                    }
                }
                catch(Exception ex)
                {
                    textBox3.AppendText("远程服务器已经中断连接"+"\r\n");
                    this.button1.Enabled = true;
                    break;
                }
            }
        }

        //获取当前系统时间
        private DateTime GetCurrentTime()
        {
            DateTime currentTime = new DateTime();
            currentTime = DateTime.Now;
            return currentTime; 
        }

        //发送字符信息到服务端的方法
        private void ClientSendMsg(string sendMsg)
        {
            //将输入的内容字符串转换为机器可以识别的字节数组   
            byte[] arrClientSendMsg = Encoding.UTF8.GetBytes(sendMsg);   
            //调用客户端套接字发送字节数组   
            socketclient.Send(arrClientSendMsg);   
            //将发送的信息追加到聊天内容文本框中   
            textBox3.AppendText(this.label4.Text+": " + GetCurrentTime() + "\r\n" + sendMsg + "\r\n\n"); 
        }



        //点击按钮button2 向服务端发送信息 
        private void button2_Click(object sender, EventArgs e)
        {
            //调用ClientSendMsg方法 将文本框中输入的信息发送给服务端   
            ClientSendMsg(textBox4.Text.Trim());
            textBox4.Clear();
        }

        
       
        private void textBox4_KeyDown_1(object sender, KeyEventArgs e)
        {
            //当光标位于文本框时 如果用户按下了键盘上的Enter键
            if (e.KeyCode == Keys.Enter)
            {
                //则调用客户端向服务端发送信息的方法  
                ClientSendMsg(textBox4.Text.Trim());
                textBox4.Clear();

            }
        }

        private void Form1_Load(object sender, EventArgs e)
        {

        }

        private void Form1_FormClosing(object sender, FormClosingEventArgs e)
        {
            DialogResult result = MessageBox.Show("是否退出？选否,最小化到托盘", "操作提示", MessageBoxButtons.YesNoCancel, MessageBoxIcon.Question);
            if (result == DialogResult.Yes)
            {
                this.Dispose();
            }
            else if (result == DialogResult.Cancel)
            {
                e.Cancel = true;
                
            }
            else
            {
                e.Cancel = true;
                this.WindowState = FormWindowState.Minimized;
                this.Visible = false;
                this.notifyIcon1.Visible = true;
                this.ShowInTaskbar = false;
            }
        }



        private void notifyIcon1_MouseDoubleClick(object sender, MouseEventArgs e)
        {
            base.Visible = true;
            this.notifyIcon1.Visible = false;
            this.ShowInTaskbar = true;
            //base.Show();
            base.WindowState = FormWindowState.Normal;
        }
    }
}

程序还有不足，后期还会继续改进

客户端在断开连接后，应该把socket关闭；

if (result == DialogResult.Yes)

 {
           if (socketclient == null)
            {
                    this.Dispose();
            }
            else
            {
                socketclient.Close();
                this.Dispose();
             }

                      }

其他错误，欢迎大家指出，需要完善的地方，也希望大家给出建议

作者:Chuck Lu GitHub

https://www.cnblogs.com/chucklu/archive/2012/11/23/2784733.html