我看书上的测试IP都是本地主机，所以没多少问题，但如何真正运用到网络上，可能还要有很多注意的细节。。。

1 using System; 2 using System.Collections.Generic; 3 using System.ComponentModel; 4 using System.Data; 5 using System.Drawing; 6 using System.Linq; 7 using System.Text; 8 using System.Threading.Tasks; 9 using System.Windows.Forms;10 using System.Net;11 using System.Net.Sockets;12 13 namespace WindowsFormsApplication114 {15     public partial class Form1 : Form16     {17         public Form1()18         {19             InitializeComponent();20         }21 22         private void button1_Click(object sender, EventArgs e)23         {24             TcpListener tcplistener = null;25             IPAddress ipaddress = IPAddress.Parse(textBox1.Text);26             int port = Convert.ToInt32(textBox2.Text);27             tcplistener = new TcpListener(ipaddress, port);28             tcplistener.Start();29             richTextBox1.Text = "等待连接。。。\n";30             TcpClient tcpclient = null;31             if (tcplistener.Pending())32                 tcpclient = tcplistener.AcceptTcpClient();33             else34                 tcpclient = new TcpClient(textBox1.Text, port);35             richTextBox1.Text += "连接成功！！\n";36             tcpclient.Close();37             tcplistener.Stop();38         }39 40         private void button2_Click(object sender, EventArgs e)41         {42             richTextBox2.Text = string.Empty;43             UdpClient udpclient = new UdpClient(Convert.ToInt32(textBox4.Text));44             udpclient.Connect(textBox3.Text, Convert.ToInt32(textBox4.Text));45             Byte[] sendBytes = Encoding.Default.GetBytes(textBox5.Text);46             udpclient.Send(sendBytes, sendBytes.Length);47             IPEndPoint ipendpoint = new IPEndPoint(IPAddress.Any, 0);48             Byte[] receiveBytes = udpclient.Receive(ref ipendpoint);49             string returnData = Encoding.Default.GetString(receiveBytes);50             richTextBox2.Text = "接收到的信息： " + returnData.ToString();51             richTextBox2.Text += "\n 这条信息来自主机 " + ipendpoint.Address.ToString()52                 + " 上的 " + ipendpoint.Port.ToString()  +"端口";53         }54     }55 }