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用C#编写一个命令行/控制台hello world程序

用C#编写一个命令行/控制台hello world程序

• 创建一个c#控制台应用
  
• 写入源代码
  客户端代码

using System;using System.Collections.Generic;using System.Linq;using System.Net;using System.Net.Sockets;using System.Text;using System.Threading.Tasks;namespace Client{
       class Program    {
           static void Main(string[] args)        {
               //提示信息            Console.WriteLine("按下任意按键开始发送...");            Console.ReadKey();            int m;            //做好链接准备            UdpClient client = new UdpClient();  //实例一个端口            IPAddress remoteIP = IPAddress.Parse("10.60.189.252");  //这个IP是我室友的电脑            int remotePort = 11000;  //设置端口号            IPEndPoint remotePoint = new IPEndPoint(remoteIP, remotePort);  //实例化一个远程端点             for (int i = 0; i < 50; i++)            {
                   //要发送的数据：第n行：hello cqjtu！重交物联2018级                string sendString = null;                sendString += "第";                m = i + 1;                sendString += m.ToString();                sendString += "行：hello cqjtu！重交物联2018级";                //定义发送的字节数组                //将字符串转化为字节并存储到字节数组中                byte[] sendData = null;                sendData = Encoding.Default.GetBytes(sendString);                client.Send(sendData, sendData.Length, remotePoint);//将数据发送到远程端点             }            client.Close();//关闭连接            //提示信息            Console.WriteLine("");            Console.WriteLine("数据发送成功，按任意键退出...");            System.Console.ReadKey();        }    }}

服务器代码

using System;using System.Collections.Generic;using System.Linq;using System.Text;using System.Threading.Tasks;using System.Net.Sockets;using System.Net;namespace server{
       class Program    {
           static void Main(string[] args)        {
               UdpClient udpRec = new UdpClient(8888);            Console.WriteLine("服务器已开启！");            try            {
                   while (true)                {
                       IPEndPoint remoteIpEndPoint = new IPEndPoint(IPAddress.Any, 0);                    byte[] recBytes = udpRec.Receive(ref remoteIpEndPoint);                    string returnData = Encoding.Default.GetString(recBytes);                    Console.WriteLine("接收到的数据是:" + returnData);                }            }            catch (Exception e)            {
                   Console.WriteLine(e);            }            finally            {
                   udpRec.Close();            }        }    }}

• 运行结果
  客户端
  
  服务器

二.用VS2015的C#编写一个简单的Form窗口程序，有一个文本框 textEdit和一个发送按钮button，运行程序后，可以在文本框里输入文字

• 创建一个新的项目
  
• 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;namespace frame_udp_server{
       public partial class Form1 : Form    {
           private UdpClient receiveUdpClient;//接收用        private UdpClient sendUdpClient;//发送用        private const int port = 65530;//和本机绑定的端口号        IPAddress ip=IPAddress.Parse("192.168.43.167");//本机ip        IPAddress remoteip=IPAddress.Parse("192.168.43.208");//远程主机ip        public Form1()        {
               InitializeComponent();            CheckForIllegalCrossThreadCalls = false;            //获取本机可用IP地址            IPAddress[] ips = Dns.GetHostAddresses(Dns.GetHostName());            foreach (IPAddress ipa in ips)            {
                   if (ipa.AddressFamily == AddressFamily.InterNetwork)                {
                       ip = ipa;                    break;                }            }            //为了在同一台机器调试，此IP也作为默认远程IP             //remoteip = ip;        }        private void Form1_Load(object sender, EventArgs e)        {
               //创建一个线程接收远程主机发来的信息            Thread myThread = new Thread(ReceiveData);            myThread.IsBackground = true;            myThread.Start();        }        //接收数据        private void ReceiveData()        {
               IPEndPoint local = new IPEndPoint(ip, port);            receiveUdpClient = new UdpClient(local);            IPEndPoint remote = new IPEndPoint(IPAddress.Any, 0);            while (true)            {
                   try                {
                       //关闭udpClient 时此句会产生异常                    byte[] receiveBytes = receiveUdpClient.Receive(ref remote);                    string receiveMessage = Encoding.Unicode.GetString(                        receiveBytes, 0, receiveBytes.Length);                    listBox1.Items.Add("收到的消息:" + receiveMessage);                }                catch                {
                       break;                }            }        }        //点击发送按钮发送数据        private void button1_Click(object sender, EventArgs e)        {
               //remoteip = IPAddress.Parse(txt_IPAddress.Text);            Thread myThread = new Thread(SendMessage);            myThread.IsBackground = true;            myThread.Start(textBox2.Text);        }        //发送消息        private void SendMessage(object obj)        {
               string message = (string)obj;            sendUdpClient = new UdpClient(0);            byte[] bytes = Encoding.Unicode.GetBytes(message);            IPEndPoint iep = new IPEndPoint(remoteip, port);            try            {
                   sendUdpClient.Send(bytes, bytes.Length, iep);                listBox1.Items.Add("发送的消息:" + message);                textBox2.Clear();            }            catch (Exception ex)            {
                   listBox1.Items.Add("发送出错:" + ex.Message);            }        }        delegate void AddItemDelegate(ListBox listbox, string text);        private void AddItem(ListBox listbox, string text)        {
               if (listbox.InvokeRequired)            {
                   AddItemDelegate d = AddItem;                //Control.Invoke 方法 (Delegate, Object[]):                //在拥有控件的基础窗口句柄的线程上，用指定的参数列表执行指定委托。                listbox.Invoke(d, new object[] {
    listbox, text });            }            else            {
                   //Add：动态的添加列表框中的项                listbox.Items.Add(text);                //SelectedIndex属性获取单项选择ListBox中当前选定项的位置                //Count：列表框中条目的总数                listbox.SelectedIndex = listbox.Items.Count - 1;                //调用此方法等效于将 SelectedIndex 属性设置为-1。                 //可以使用此方法快速取消选择列表中的所有项。                listbox.ClearSelected();            }        }        delegate void ClearTextBoxDelegate();        private void ClearTextBox()        {
               if (textBox2.InvokeRequired)            {
                   ClearTextBoxDelegate d = ClearTextBox;                textBox2.Invoke(d);            }            else            {
                   textBox2.Clear();                textBox2.Focus();            }        }        private void label2_Click(object sender, EventArgs e)        {
           }        private void label2_Click_1(object sender, EventArgs e)        {
           }    }}```- 结果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;namespace frame_udp_server{
       public partial class Form1 : Form    {
           private UdpClient receiveUdpClient;//接收用        private UdpClient sendUdpClient;//发送用        private const int port = 65530;//和本机绑定的端口号        IPAddress ip=IPAddress.Parse("192.168.43.167");//本机ip        IPAddress remoteip=IPAddress.Parse("192.168.43.208");//远程主机ip        public Form1()        {
               InitializeComponent();            CheckForIllegalCrossThreadCalls = false;            //获取本机可用IP地址            IPAddress[] ips = Dns.GetHostAddresses(Dns.GetHostName());            foreach (IPAddress ipa in ips)            {
                   if (ipa.AddressFamily == AddressFamily.InterNetwork)                {
                       ip = ipa;                    break;                }            }            //为了在同一台机器调试，此IP也作为默认远程IP             //remoteip = ip;        }        private void Form1_Load(object sender, EventArgs e)        {
               //创建一个线程接收远程主机发来的信息            Thread myThread = new Thread(ReceiveData);            myThread.IsBackground = true;            myThread.Start();        }        //接收数据        private void ReceiveData()        {
               IPEndPoint local = new IPEndPoint(ip, port);            receiveUdpClient = new UdpClient(local);            IPEndPoint remote = new IPEndPoint(IPAddress.Any, 0);            while (true)            {
                   try                {
                       //关闭udpClient 时此句会产生异常                    byte[] receiveBytes = receiveUdpClient.Receive(ref remote);                    string receiveMessage = Encoding.Unicode.GetString(                        receiveBytes, 0, receiveBytes.Length);                    listBox1.Items.Add("收到的消息:" + receiveMessage);                }                catch                {
                       break;                }            }        }        //点击发送按钮发送数据        private void button1_Click(object sender, EventArgs e)        {
               //remoteip = IPAddress.Parse(txt_IPAddress.Text);            Thread myThread = new Thread(SendMessage);            myThread.IsBackground = true;            myThread.Start(textBox2.Text);        }        //发送消息        private void SendMessage(object obj)        {
               string message = (string)obj;            sendUdpClient = new UdpClient(0);            byte[] bytes = Encoding.Unicode.GetBytes(message);            IPEndPoint iep = new IPEndPoint(remoteip, port);            try            {
                   sendUdpClient.Send(bytes, bytes.Length, iep);                listBox1.Items.Add("发送的消息:" + message);                textBox2.Clear();            }            catch (Exception ex)            {
                   listBox1.Items.Add("发送出错:" + ex.Message);            }        }        delegate void AddItemDelegate(ListBox listbox, string text);        private void AddItem(ListBox listbox, string text)        {
               if (listbox.InvokeRequired)            {
                   AddItemDelegate d = AddItem;                //Control.Invoke 方法 (Delegate, Object[]):                //在拥有控件的基础窗口句柄的线程上，用指定的参数列表执行指定委托。                listbox.Invoke(d, new object[] {
    listbox, text });            }            else            {
                   //Add：动态的添加列表框中的项                listbox.Items.Add(text);                //SelectedIndex属性获取单项选择ListBox中当前选定项的位置                //Count：列表框中条目的总数                listbox.SelectedIndex = listbox.Items.Count - 1;                //调用此方法等效于将 SelectedIndex 属性设置为-1。                 //可以使用此方法快速取消选择列表中的所有项。                listbox.ClearSelected();            }        }        delegate void ClearTextBoxDelegate();        private void ClearTextBox()        {
               if (textBox2.InvokeRequired)            {
                   ClearTextBoxDelegate d = ClearTextBox;                textBox2.Invoke(d);            }            else            {
                   textBox2.Clear();                textBox2.Focus();            }        }        private void label2_Click(object sender, EventArgs e)        {
           }        private void label2_Click_1(object sender, EventArgs e)        {
           }    }}

• 结果
  

三、安装wireshark 抓包软件，抓取上述程序发送的网络包，对数据帧结构进行分析。

• 1.打开wireshark进行抓包
  （1）从跟踪中选择一个 UDP 数据包。从此数据包中，确定 UDP 标头中有多少字段，并为这些字段命名，抓取一个包
  
• 2.分析UDP数据包的格式
  UDP 的标头有 4 个字段，一共 8 byte，各字段分别为：
  Source Port：源端口号
  Destination Port：目的端口号
  Length：长度
  Checksum：校验和

四、总结

太好了，真不错，下次还来

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