Socket-服务器端与客户端互相通信

一.连接

1.服务器端开始监听

2.客户端Connect()连接服务器端

3.服务器端Accept()产生新的socket，一次连接完成，此时服务器端与客户端就可以使用Send和Receive发送和接受数据

二.发送数据和文件

1.一端发送数据时，在包头（也可以包尾）加上特殊一个字符（比如0和1），另一端先判断包的第一个字符是什么，比如0就是字符串，1就是文件，然后读取数据

2.一段发送文件时，应该先发送文件名，再发送文件，另一端先获取文件名，再根据文件名，把数据保存本地。

三.代码

客户端代码：

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

namespace SOCKET_Client
{
    public partial class Form1 : Form
    {
        public Form1()
        {
            InitializeComponent();
            this.FormClosed += Form1_FormClosed;
        }

        private void Form1_FormClosed(object sender, FormClosedEventArgs e)
        {
            SafeClose(socketSend);
        }

        Socket socketSend;
        string FileName;
        private void button1_Click(object sender, EventArgs e)
        {
            try
            {
                // 创建负责通信的Socket
                socketSend = new Socket(AddressFamily.InterNetwork, SocketType.Stream, ProtocolType.Tcp);
                IPAddress ip = IPAddress.Parse(TxtIpAddress.Text.Trim());
                IPEndPoint point = new IPEndPoint(ip, Convert.ToInt32(txtPort.Text.Trim()));
                // 获得要连接的远程服务器应用程序的ip地址和端口号
                socketSend.Connect(point);
                ShowMsg("连接成功");
                // 开启一个新的线程不停的接受服务端发来的消息
                Thread th = new Thread(Recive);
                th.IsBackground = true;
                th.Start();
            }
            catch { }     
        }
        /// <summary>
        /// 不停的接受服务器发来的消息
        /// </summary>
        void Recive()
        {
            try
            {
                while (true)
                {
                    byte[] buffer = new byte[1024 * 1024 * 3];
                    // 实际接受到的有效字节数
                    int r = socketSend.Receive(buffer);
                    if (r == 0)
                    {
                        break;
                    }
                    // 判断第一位
                    switch (buffer[0])
                    {
                        case 0:
                            string str = Encoding.UTF8.GetString(buffer, 1, r-1);
                            //MessageBox.Show(str);
                            ShowMsg(socketSend.RemoteEndPoint + ":" + str);
                            break;
                        case 1:                                                  
                                using(FileStream fsWrite=new FileStream(@"C:"+FileName,FileMode.OpenOrCreate,FileAccess.Write))
                                {
                                    fsWrite.Write(buffer,1,r-1);
                                }
                                MessageBox.Show("保存成功！");                          
                            break;
                        case 3:
                            //获取文件文件名
                           FileName = Encoding.UTF8.GetString(buffer, 1, r - 1);
                            break;
                        case 2:
                            ZhenDong();
                            break;
                     
                    }                 
                   
                }
            }
            catch { }         
        }
        /// <summary>
        /// 震动
        /// </summary>
        void ZhenDong()
        {
            int posX = this.Location.X;
            int posY = this.Location.Y;
            for (int i = 0; i < 300; i++)
            {
                this.Location = new Point(posX-200,posY-200);
                this.Location = new Point(posX, posY);
            }
        }
        void ShowMsg(string str)
        {
            richTextBox1.AppendText(str + "
");
        }
        /// <summary>
        /// 客户端给服务器发送消息
        /// </summary>
        /// <param name="sender"></param>
        /// <param name="e"></param>
        private void button2_Click(object sender, EventArgs e)
        {
            try
            {
                if (richTextBox2.Text.Trim() == "")
                {
                    MessageBox.Show("当前无发送内容！");
                    return;
                }
                string str = richTextBox2.Text.Trim();
                byte[] buffer = Encoding.UTF8.GetBytes(str);
                socketSend.Send(buffer);
                richTextBox2.Clear();
            }
            catch { }

        }
        public  void SafeClose( Socket socket)
        {
            if (socket == null)
                return;

            if (!socket.Connected)
                return;

            try
            {
                socket.Shutdown(SocketShutdown.Both);
            }
            catch
            {
            }

            try
            {
                socket.Close();
            }
            catch
            {
            }
        }
        private void Form1_Load(object sender, EventArgs e)
        {
            Control.CheckForIllegalCrossThreadCalls = false;
        }

        private void button3_Click(object sender, EventArgs e)
        {
            SafeClose(socketSend);
        }
    }
}

服务器端代码

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.Threading.Tasks;
using System.Windows.Forms;
using System.Threading;
using System.IO;
using Timer = System.Windows.Forms.Timer;

namespace SOCKET_Test
{
    public partial class Form1 : Form
    {
        public Form1()
        {
            InitializeComponent();
        }
        Thread th;
        Thread thAccept;
        private void btnStart_Click(object sender, EventArgs e)
        {
            try
            {
                // 当点击开始监听的时候，在服务器端创建一个负责监听Ip地址跟端口号的Socket
                Socket socketWatch = new Socket(AddressFamily.InterNetwork, SocketType.Stream, ProtocolType.Tcp);
                IPAddress ip = IPAddress.Any; // IPAddress.Parse(txtserver.text)
                // 创建端口号对象
                IPEndPoint point = new IPEndPoint(ip, Convert.ToInt32(txtPort.Text.Trim()));
                // 监听
                socketWatch.Bind(point);
                ShowMsg("监听成功");
                socketWatch.Listen(10);
                Timer timer = new Timer();
                timer.Tick += Timer_Tick;
                timer.Interval = 1000;
                //timer.tick+= new ElapsedEventHandler(timer_Elapsed);
                timer.Start();
                th = new Thread(Listen);
                th.IsBackground = true;
                th.Start(socketWatch);
            }
            catch (Exception o)
            {
                MessageBox.Show(o.ToString());
            }
        }

        private void Timer_Tick(object sender, EventArgs e)
        {
            if (dicSocket.Count > 0)
            {
                for (int i = dicSocket.Count - 1; i >= 0; i--)
                {

                    string sendStr = "Server Information";
                    byte[] bs = Encoding.ASCII.GetBytes(sendStr);
                    if (dicSocket.ToList()[i].Value.Poll(1000, SelectMode.SelectRead))
                    //SelectMode.SelectRead表示，如果已调用 并且有挂起的连接，true。
                    //- 或 - 如果有数据可供读取，则为 true。- 或 - 如果连接已关闭、重置或终止，则返回 true（此种情况就表示若客户端断开连接了，则此方法就返回true）； 否则，返回 false。

                    {
                        //dicSocket.ToList()[i].Value.Close();//关闭socket
                        dicSocket.ToList().RemoveAt(i);//从列表中删除断开的socke
                        comboBox1.Items.Remove(dicSocket.ToList()[i].Value.RemoteEndPoint.ToString());
                        continue;

                    }
                    dicSocket.ToList()[i].Value.Send(bs, bs.Length, 0);

                }
            }
        }


        Socket socketSend;
        /// <summary>
        /// 等待客户端的链接，并且创建与之通信用的Socket
        /// </summary>
        void Listen(object obj)
        {
            Socket socketWatch = obj as Socket;
            // 等待客户端的连接
            while(true)
            {
                try
                {
                    socketSend = socketWatch.Accept();
                    // 将远程连接的客户端的IP地址和Socket存入集合中
                    dicSocket.Add(socketSend.RemoteEndPoint.ToString(),socketSend);
                    comboBox1.Items.Add(socketSend.RemoteEndPoint.ToString());
                    ShowMsg(socketSend.RemoteEndPoint.ToString() + ":" + "连接成功");
                    // 客户端连接成功之后，服务器应该接受客户端发来的消息
                    thAccept = new Thread(Recive);
                    thAccept.IsBackground = true;
                    thAccept.Start(socketSend);
                }
                catch { }
            }     
        }
        // 将远程连接的客户端的IP地址和Socket存入集合中
        Dictionary<string, Socket> dicSocket = new Dictionary<string, Socket>();
        /// <summary>
        /// 服务器不停的接受客户端发送过来的请求
        /// </summary>
        /// <param name="obj"></param>
        public void Recive(object obj)
        {
            Socket socketSend = obj as Socket;
            while(true)
            {
                try
                {
                    byte[] buffer = new byte[1024 * 1024 * 2];
                    // 实际接受到的有效字节数
                    int r = socketSend.Receive(buffer);
                    if (r == 0)
                    {
                        break;
                    }
                    string str = Encoding.UTF8.GetString(buffer, 0, r);
                    ShowMsg(socketSend.RemoteEndPoint + ":" + str);
                }
                catch
                {              
                }        
            }       
        }
        void ShowMsg(string str)
        {
            richTextBox1.AppendText(str+"
");
        }

        private void Form1_Load(object sender, EventArgs e)
        {
            Control.CheckForIllegalCrossThreadCalls = false;
        }
        /// <summary>
        /// 服务器给客户端发送消息
        /// </summary>
        /// <param name="sender"></param>
        /// <param name="e"></param>
        private void button1_Click(object sender, EventArgs e)
        {
            try
            {
                if(richTextBox2.Text.Trim() == "")
                {
                    MessageBox.Show("当前无发送内容");
                    return;
                }
                string str = richTextBox2.Text.Trim();
                byte[] buffer = Encoding.UTF8.GetBytes(str);
                List<byte> ls = new List<byte>();
                ls.Add(0);
                ls.AddRange(buffer);
                byte[] newBuffer = ls.ToArray();
                // 获得用户在下拉框中选中的IP地址
                //socketSend.Send(buffer);
                string ip = comboBox1.SelectedItem.ToString();
                dicSocket[ip].Send(newBuffer);
                richTextBox2.Clear();
            }
            catch { }
        }

        OpenFileDialog ofd = new OpenFileDialog();

        /// <summary>
        /// 选择要发送的文件
        /// </summary>
        /// <param name="sender"></param>
        /// <param name="e"></param>
        /// 
        private void button2_Click(object sender, EventArgs e)
        {
            try
            {
                ofd.InitialDirectory = @"D:";
                ofd.Title = "请选择！";
                ofd.Filter = "所有文件|*.*";
                ofd.ShowDialog();
                if (ofd.FileName != "")
                {
                    textBox1.Text = ofd.FileName;
                }          
            }
            catch { }        
        }

        private void button3_Click(object sender, EventArgs e)
        {
            try
            {
                if (comboBox1.SelectedItem == null)
                {
                    MessageBox.Show("请选择客户端IP");
                    return;
                }
                if (textBox1.Text.Trim() == "")
                {
                    MessageBox.Show("当前无发送内容!");
                    return;
                }
                // 获得要发送文件的路径
                string strPath = textBox1.Text.Trim();
                using (FileStream fsRead = new FileStream(strPath, FileMode.OpenOrCreate, FileAccess.Read))
                {
                    

                    #region 发送文件名给客户端
                    byte[] buffer1 = Encoding.UTF8.GetBytes(System.IO.Path.GetFileName(ofd.FileName));
                    List<byte> ls1 = new List<byte>();
                    ls1.Add(3);
                    ls1.AddRange(buffer1);
                    byte[] newBuffer1 = ls1.ToArray();
                    dicSocket[comboBox1.SelectedItem.ToString()].Send(newBuffer1);
                    #endregion

                    #region 发送文件给客户端
                    byte[] buffer = new byte[1024 * 1024 * 3];
                    int r = fsRead.Read(buffer, 0, buffer.Length);
                    List<byte> ls = new List<byte>();
                    ls.Add(1);
                    ls.AddRange(buffer);
                    byte[] newBuffer = ls.ToArray();
                    dicSocket[comboBox1.SelectedItem.ToString()].Send(newBuffer, 0, r + 1, SocketFlags.None);
                    #endregion
                    richTextBox2.Clear();
                }
            }
            catch { }         
        }
        /// <summary>
        /// 发送震动
        /// </summary>
        /// <param name="sender"></param>
        /// <param name="e"></param>
        private void button4_Click(object sender, EventArgs e)
        {
            try
            {
                byte[] buffer = new byte[1];
                buffer[0] = 2;
                dicSocket[comboBox1.SelectedItem.ToString()].Send(buffer);
            }
            catch { }
        }
    }
}

参考博客（加了几个自我定义的功能，如服务器端判断客户端是否断开）

https://www.cnblogs.com/zzp0320/p/7909828.html