C# 網(wǎng)絡(luò)編程之UDP

更新時(shí)間：2021年02月19日 10:46:39 作者：seabluescn

這篇文章主要介紹了C# 網(wǎng)絡(luò)編程之UDP的相關(guān)資料，幫助大家更好的理解和使用c#，感興趣的朋友可以了解下

一、概述

UDP和TCP是網(wǎng)絡(luò)通訊常用的兩個(gè)傳輸協(xié)議，C#一般可以通過Socket來實(shí)現(xiàn)UDP和TCP通訊，由于.NET框架通過UdpClient、TcpListener 、TcpClient這幾個(gè)類對(duì)Socket進(jìn)行了封裝，使其使用更加方便，本文就通過這幾個(gè)封裝過的類講解一下相關(guān)應(yīng)用。

二、UDP基本應(yīng)用

與TCP通信不同，UDP通信是不分服務(wù)端和客戶端的，通信雙方是對(duì)等的。為了描述方便，我們把通信雙方稱為發(fā)送方和接收方。

發(fā)送方：

首先創(chuàng)建一個(gè)UDP對(duì)象：

string locateIP = "127.0.0.1"; //本機(jī)IP

   int locatePort = 9001;   //發(fā)送端口

   IPAddress locateIpAddr = IPAddress.Parse(locateIP);

   IPEndPoint locatePoint = new IPEndPoint(locateIpAddr, locatePort);

   UdpClient udpClient = new UdpClient(locatePoint);

發(fā)送數(shù)據(jù)：

string remoteIP = "127.0.0.1";    //目標(biāo)機(jī)器IP

   int remotePort = 9002;      //接收端口   

   IPAddress remoteIpAddr = IPAddress.Parse(remoteIP);

   IPEndPoint remotePoint = new IPEndPoint(remoteIpAddr, remotePort);

   byte[] buffer = Encoding.UTF8.GetBytes(“hello”);

   udpClient.Send(buffer, buffer.Length, remotePoint);

以上就完成了一個(gè)發(fā)送任務(wù)，一個(gè)較完整的發(fā)送代碼如下：

public partial class FormServer : Form
 {
  private UdpClient udpClient = null;

  private void btnConnect_Click(object sender, EventArgs e)
  {
   string locateIP = "127.0.0.1";
   int locatePort = 9001;
   IPAddress locateIpAddr = IPAddress.Parse(locateIP);
   IPEndPoint locatePoint = new IPEndPoint(locateIpAddr, locatePort);
   udpClient = new UdpClient(locatePoint);

   this.groupWork.Enabled = true;
  }

  private void Send_Click(object sender, EventArgs e)
  {
   string text = this.txtSend.Text.Trim();
   string remoteIP = "127.0.0.1";
   int remotePort = 9002;
   byte[] buffer = Encoding.UTF8.GetBytes(text);

   if (udpClient != null)
   {
    IPAddress remoteIp = IPAddress.Parse(remoteIP);
    IPEndPoint remotePoint = new IPEndPoint(remoteIp, remotePort);
    udpClient.Send(buffer, buffer.Length, remotePoint);
   }

   Debug.WriteLine("Send OK");
  }
 }

接收端：

首先創(chuàng)建一個(gè)UDP對(duì)象：

string locateIP = "127.0.0.1";

   int locatePort = 9002;

   IPAddress locateIpAddr = IPAddress.Parse(locateIP);

   IPEndPoint locatePoint = new IPEndPoint(locateIpAddr, locatePort);

   UdpClient udpClient = new UdpClient(locatePoint);

接收數(shù)據(jù)：

IPEndPoint remotePoint = new IPEndPoint(IPAddress.Parse("1.1.1.1"), 1);

  var received = udpClient.Receive(ref remotePoint);

  string info = Encoding.UTF8.GetString(received);

  string from=$” {remotePoint.Address}:{remotePoint.Port}”;

注意兩點(diǎn)：

1、remotePoint是獲得發(fā)送方的IP信息，定義時(shí)可以輸入任何合法的IP和端口信息；

2、Receive方法是阻塞方法，所以需要在新的線程內(nèi)運(yùn)行，程序會(huì)一直等待接收數(shù)據(jù)，當(dāng)接收到一包數(shù)據(jù)時(shí)程序就返回，要持續(xù)接收數(shù)據(jù)需要重復(fù)調(diào)用Receive方法。

一個(gè)較完整的接收端代碼如下：

public partial class FormClent : Form
 {
  private UdpClient udpClient = null; 

  private void btnConnect_Click(object sender, EventArgs e)
  {
   string locateIP = "127.0.0.1";
   int locatePort = 9002;
   IPAddress locateIpAddr = IPAddress.Parse(locateIP);
   IPEndPoint locatePoint = new IPEndPoint(locateIpAddr, locatePort);
   udpClient = new UdpClient(locatePoint);
   IPEndPoint remotePoint = new IPEndPoint(IPAddress.Parse("1.1.1.1"), 1);

   Task.Run(() =>
   {
    while (true)
    {
     if (udpClient != null)
     {
      var received = udpClient.Receive(ref remotePoint);
      string info = Encoding.UTF8.GetString(received);
      string from=$” {remotePoint.Address}:{remotePoint.Port}”; 
     }
    }
   }); 
  }
 }

三、丟包和亂序問題

當(dāng)發(fā)送端發(fā)送一包數(shù)據(jù)時(shí)，不管對(duì)方是否接收都是發(fā)送成功的，UDP協(xié)議本身并不會(huì)對(duì)發(fā)送的可靠性進(jìn)行驗(yàn)證。（這里的可靠性是指是否接收到，如果對(duì)方接收到數(shù)據(jù)包，其內(nèi)容還是可靠的，這個(gè)在鏈路層進(jìn)行了保證。）同時(shí)，由于網(wǎng)絡(luò)延時(shí)等因素，先發(fā)送的包并不能確定先被接收到，所以由于這兩個(gè)原因，UDP通信存在丟包和亂序的情況。

某些業(yè)務(wù)場景下，比如實(shí)時(shí)狀態(tài)監(jiān)控，可能對(duì)丟包和亂序情況并不敏感，可以不用處理，但大部分情況下還是介意丟包的，簡單的處理辦法就是把包的頭部固定長度的空間拿出來存放核對(duì)信息，比如包編號(hào)，如果有缺失，可以要求發(fā)送方重發(fā)，也可以進(jìn)行排序。

四、將數(shù)據(jù)接收包裝為事件

我們對(duì)UdpClent又進(jìn)行一次封裝，啟用一個(gè)線程進(jìn)行接收數(shù)據(jù)，將接收到的數(shù)據(jù)包通過事件發(fā)布出來，這樣使用起來就更方便了。

namespace Communication.UDPClient
{
 public class UdpStateEventArgs : EventArgs
 {  
  public IPEndPoint remoteEndPoint;  
  public byte[] buffer = null;
 }

 public delegate void UDPReceivedEventHandler(UdpStateEventArgs args);

 public class UDPClient
 {
  private UdpClient udpClient;
  public event UDPReceivedEventHandler UDPMessageReceived;

  public UDPClient(string locateIP, int locatePort)
  {
   IPAddress locateIp = IPAddress.Parse(locateIP);
   IPEndPoint locatePoint = new IPEndPoint(locateIp, locatePort);
   udpClient = new UdpClient(locatePoint);

   //監(jiān)聽創(chuàng)建好后，創(chuàng)建一個(gè)線程，開始接收信息
   Task.Run(() =>
   {
    while (true)
    {
     UdpStateEventArgs udpReceiveState = new UdpStateEventArgs();

     if (udpClient != null)
     {
      IPEndPoint remotePoint = new IPEndPoint(IPAddress.Parse("1.1.1.1"), 1);
      var received = udpClient.Receive(ref remotePoint);
      udpReceiveState.remoteEndPoint = remotePoint;
      udpReceiveState.buffer = received;
      UDPMessageReceived?.Invoke(udpReceiveState);
     }
     else
     {
      break;
     }
    }
   });
  }
 }
}

具體使用辦法：

private void btnConnect_Click(object sender, EventArgs e)
  {
   string locateIP = "127.0.0.1";
   int locatePort = 9002;   
   UDPClient udpClient = new UDPClient(locateIP, locatePort);
   udpClient.UDPMessageReceived += UdpClient_UDPMessageReceived;   
  }

  private void UdpClient_UDPMessageReceived(UdpStateEventArgs args)
  {
   var remotePoint = args.remoteEndPoint;
   string info = Encoding.UTF8.GetString(args.buffer); 
  }