c# 服务端

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.Net.Sockets;
using System.Net;
using System.Threading;
using System.IO;

namespace WindowsFormsApplication1
{
    public partial class Form1 : Form
    {

        Dictionary<string, Socket> d = new Dictionary<string, Socket>();
        public Form1()
        {
            InitializeComponent();
        }
        Socket so;

        private void button1_Click(object sender, EventArgs e)
        {
            string str = this.textBox1.Text.Trim();
            Byte[] buf = System.Text.Encoding.UTF8.GetBytes(str);
            //Byte[] buffernew = new Byte[buf.Length + 1];
            //buffernew[0] = 0;
            //int i = 1;
            //foreach (byte a in buf)
            //{
            //    buffernew[i] = a;
            //    i++;
            //}
            List<byte> list = new List<byte>();
            list.Add(0);
            list.AddRange(buf);
            byte[] buffernew = list.ToArray();
            d[comboBox1.SelectedItem.ToString()].Send(buffernew);
            //a.Send(buf);
        }

        private void button2_Click(object sender, EventArgs e)
        {
            string id = this.ip.Text;
            int port = Convert.ToInt32(this.port.Text);
            IPAddress ip = IPAddress.Parse(id);
            IPEndPoint ports = new IPEndPoint(ip,port);
            so = new Socket(AddressFamily.InterNetwork,SocketType.Stream,ProtocolType.Tcp);
            so.Bind(ports);
            so.Listen(10);
            Thread d = new Thread(client);
            d.IsBackground = true;
            d.Start(so);

        }

        public void listin(string msg)
        {

            this.textBox2.AppendText(msg + "\r\n");

        }

        //public void ceshi()
        //{
        //    while (true)
        //    {
        //        Socket ce = so.Accept();
        //        listin(ce.RemoteEndPoint.ToString()+"连接成功");
        //        Thread ax = new Thread(client);
        //        ax.Start(ce);

        //    }

        //}

        public void client(object o)
        {
            Socket s = o as Socket;

            while (true)
            {
                Socket a = s.Accept();
                d.Add(a.RemoteEndPoint.ToString(), a);
                this.comboBox1.Items.Add(a.RemoteEndPoint.ToString());
                listin(a.RemoteEndPoint.ToString() + "连接成功");
                Thread th = new Thread(recevie);
                th.IsBackground = false;
                th.Start(a);

            }

        }

        void recevie(object o)
        {
            Socket a = o as Socket;
            while (true)
            {
                Byte[] buffer = new Byte[1024 * 1024 * 3];
                int t = a.Receive(buffer);
                if (t == 0)
                {
                    break;
                }
                string str = Encoding.UTF8.GetString(buffer, 0, t);
                listin(a.RemoteEndPoint.ToString() + ":" + str);
            }
        }

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

        private void button3_Click(object sender, EventArgs e)
        {
            OpenFileDialog open = new OpenFileDialog();//创建对话框
            open.InitialDirectory = @"C:\Documents and Settings\All Users\桌面"; //设置对话框路径
            open.Title = "对话框1"; //对话框标题
            open.Filter = "所有文件|*.*";
            open.Multiselect = true; //多选
            open.ShowDialog(); //打开对话框
            string paths = open.FileName;  //读取文件的全路径
            if (paths == "") return;
            this.textBox3.Text = paths;

        }

        private void button4_Click(object sender, EventArgs e)
        {
            string path = this.textBox3.Text;
            using (FileStream fs = new FileStream(path, FileMode.Open, FileAccess.Read))
            {
                byte[] bytes = new byte[1024 * 1024 * 5];
                int r = fs.Read(bytes, 0, bytes.Length);
                List<byte> list = new List<byte>();
                list.Add(1);
                list.AddRange(bytes);
                byte[] buffernew = list.ToArray();
                d[comboBox1.SelectedItem.ToString()].Send(buffernew,0,r+1,SocketFlags.None);
            }
        }

        private void button5_Click(object sender, EventArgs e)
        {
            byte[] buf = new byte[1];
            buf[0] = 2;
            List<byte> list = new List<byte>();
            list.Add(2);
            list.AddRange(buf);
            byte[] buffernew = list.ToArray();
            d[comboBox1.SelectedItem.ToString()].Send(buffernew);
        }
    }
}