C#文件发送

using System;  
using System.Collections.Generic;  
using System.ComponentModel;  
using System.Data;  
using System.Drawing;  
using System.Text;  
using System.Windows.Forms;  
  
using System.IO;  
using System.Net;  
using System.Net.Sockets;  
using System.Threading;   
  
namespace FileClientSocket  
{  
    public partial class Form1 : Form  
    {  
        public Form1()  
        {  
            InitializeComponent();  
        }  
  
        private void Form1_Load(object sender, EventArgs e)  
        {  
            //获得本机的IP地址      
            this.textBox4.Text = Dns.GetHostByName(Dns.GetHostName()).AddressList[0].ToString();     
  
        }  
  
        private void StartSend()