TcpSend窗口用于发送消息，另外写一个用于接收消息的应用程序，消息接受到以后，必须要关闭接收消息的窗口，才能在接收新的消息，不知道怎么能解决这个问题。

源代码：

发送消息的窗口代码

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

namespace TCPSocket
{
    public partial class FrmTcpSend : Form
    {
        public FrmTcpSend()
        {
            InitializeComponent();
        }

private void buttonSendFile_Click(object sender, EventArgs e)
        {
           // TcpClient tcpClient = new TcpClient(textBoxHostName.Text, Int32.Parse(textBoxPort.Text));
            TcpClient tcpClient = new TcpClient();
            tcpClient.Connect(IPAddress.Parse(textBoxHostName.Text), Int32.Parse(textBoxPort.Text));

NetworkStream ns = tcpClient.GetStream();

FileStream fs = File.Open("..\\..\\FrmTcpSend.cs", FileMode.Open);

int data = fs.ReadByte();

while (data != -1)
            {
                ns.WriteByte((byte)data);
                data = fs.ReadByte();
            }

fs.Close();
            ns.Close();
            tcpClient.Close();

}

private void buttonSendMessage_Click(object sender, EventArgs e)
        {
            TcpClient tcpClient = new TcpClient();
            tcpClient.Connect(IPAddress.Parse(textBoxHostName.Text), Int32.Parse(textBoxPort.Text));

NetworkStream ns = tcpClient.GetStream();

if (ns.CanWrite)
            {
                Byte[] sendBytes = Encoding.UTF8.GetBytes(textBoxMessage.Text);
                ns.Write(sendBytes, 0, sendBytes.Length);
            }
            else
            {
                MessageBox.Show("不能写入数据流", "终止", MessageBoxButtons.OK, MessageBoxIcon.Stop);
                //Console.WriteLine("You cannot write data to this stream.");
                tcpClient.Close();

// Closing the tcpClient instance does not close the network stream.
                ns.Close();
                return;
            }

ns.Close();
            tcpClient.Close();

}
    }
}