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用C#实现UDP服务器

article 2026/2/21 20:35:04

对UDP服务器的要求

如同TCP通信一样让UDP服务端可以服务多个客户端
需要具备的条件：
1.区分消息类型(不需要处理分包、黏包)
2.能够接收多个客户端的消息
3.能够主动给自己发过消息的客户端发消息(记录客户端信息)
4.主动记录上次收到客户端消息的时间，如果长时间没有收到消息，主动移除记录的客户端信息

分析：
1.UDP是无连接的，我们如何记录连入的客户端
2.UDP收发消息都是通过一个Socket来处理，我们应该如何和处理收发消息
3.如果不使用心跳消息，如何记录上次收到消息的时间

基本数据类--封装序列化和反序列化等方法

此代码定义了一个抽象基类BaseData，其中包含抽象方法用于获取字节数组容器大小、序列化和反序列化成员变量，还提供了一系列受保护的方法用于在字节数组和不同数据类型（如int、short、long等）及字符串、BaseData子类对象之间进行读写操作。

using System;
using System.Collections;
using System.Collections.Generic;
using System.Text;public abstract class BaseData
{//用于子类重写的 获取字节数组容器大小的方法public abstract  int GetBytesNum();//把成员变量序列化为对应的字节数组public abstract byte[] Writing();public abstract int Reading(byte[] bytes, int beginIndex=0);//bytes指定的字节数组//value具体的int值//index索引位置的变量protected void WriteInt(byte []bytes,int value,ref int index){BitConverter.GetBytes(value).CopyTo(bytes, index);index += sizeof(int);}protected void WriteShort(byte[]bytes,short value,ref int index){BitConverter.GetBytes(value).CopyTo(bytes, index);index += sizeof(short);}protected void WriteLong(byte[]bytes,long value,ref int index){BitConverter.GetBytes(value).CopyTo(bytes, index);index += sizeof(long);}protected void WriteFloat(byte[] bytes, float value, ref int index){BitConverter.GetBytes(value).CopyTo(bytes, index);index += sizeof(float);}protected void WriteByte(byte[]bytes,byte value,ref int index){bytes[index] = value;index += sizeof(byte);}protected void WriteBool(byte[] bytes, bool value, ref int index){BitConverter.GetBytes(value).CopyTo(bytes, index);index += sizeof(bool);}protected void WriteString(byte[]bytes,string value,ref int index){//先存储string字节数组的长度byte[] strBytes = Encoding.UTF8.GetBytes(value);//BitConverter.GetBytes(strBytes.Length).CopyTo(bytes, index);//index += sizeof(int);WriteInt(bytes, strBytes.Length, ref index);//再存string字节数组strBytes.CopyTo(bytes, index);index += strBytes.Length;}protected void WriteData(byte[]bytes,BaseData data,ref int index){data.Writing().CopyTo(bytes, index);index += data.GetBytesNum();}protected int ReadInt(byte[]bytes,ref int index){int value = BitConverter.ToInt32(bytes, index);index += 4;return value;}protected short ReadShort(byte[] bytes, ref int index){short value = BitConverter.ToInt16(bytes, index);index += 2;return value;}protected long ReadLong(byte[] bytes, ref int index){long value = BitConverter.ToInt64(bytes, index);index += 8;return value;}protected float ReadFloat(byte[] bytes, ref int index){float value = BitConverter.ToSingle(bytes, index);index += sizeof(float);return value;}protected byte ReadByte(byte[] bytes, ref int index){byte value = bytes[index];index += 1;return value;}protected bool ReadBool(byte[] bytes, ref int index){bool value = BitConverter.ToBoolean(bytes, index);index += sizeof(bool);return value;}protected string ReadString(byte[] bytes, ref int index){int length = ReadInt(bytes, ref index);string value = Encoding.UTF8.GetString(bytes, index, length);index += length;return value;}protected T ReadData<T>(byte[] bytes, ref int index) where T : BaseData, new(){T value = new T();index+= value.Reading(bytes,index);return value;}
}

基本消息类

这段代码定义了一个名为BaseMsg的类，它继承自BaseData类。BaseMsg类重写了BaseData的抽象方法GetBytesNum、Reading和Writing，但这些重写方法只是简单抛出NotImplementedException异常，表明目前未实现具体逻辑。此外，BaseMsg类还定义了一个虚方法GetID，默认返回 0。

BaseMsg类的设计目的主要是作为消息类的基类，为后续具体消息类的实现提供统一的接口和结构框架。

using System.Collections;
using System.Collections.Generic;public class BaseMsg : BaseData
{public override int GetBytesNum(){throw new System.NotImplementedException();}public override int Reading(byte[] bytes, int beginIndex = 0){throw new System.NotImplementedException();}public override byte[] Writing(){throw new System.NotImplementedException();}public virtual int GetID(){return 0;}
}

玩家信息类

这段代码定义了一个名为PlayerMsg的类，它继承自BaseMsg类。PlayerMsg类代表了与玩家相关的消息，并且实现了消息的序列化和反序列化功能。

using System.Collections;
using System.Collections.Generic;public class PlayerMsg : BaseMsg
{public int playerID;public PlayerData playerData;public override int GetBytesNum(){return 4 +//消息ID4 +//playerID长度playerData.GetBytesNum();//消息的长度}public override int GetID(){return 1001;}public override int Reading(byte[] bytes, int beginIndex = 0){//反序列化不需要去解析ID,因为在这一步之前，就应该将ID反序列化出来//用来判断到底使用哪一个自定义类来反序列化int index = beginIndex;playerID = ReadInt(bytes, ref index);playerData = ReadData<PlayerData>(bytes, ref index);return index - beginIndex;}public override byte[] Writing(){int index = 0;byte[] playerBytes = new byte[GetBytesNum()];//先写消息IDWriteInt(playerBytes, GetID(), ref index);WriteInt(playerBytes, playerID, ref index);WriteData(playerBytes, playerData, ref index);return playerBytes;}
}

using System.Collections;
using System.Collections.Generic;
using System.Text;public class PlayerData : BaseData 
{public string name; public int lev;public int atk;public override int GetBytesNum(){return 4 + 4 + 4 + Encoding.UTF8.GetBytes(name).Length;}public override int Reading(byte[] bytes, int beginIndex = 0){int index = beginIndex;name=ReadString(bytes, ref index);lev=ReadInt(bytes, ref index);atk=ReadInt(bytes, ref index);return index - beginIndex;}public override byte[] Writing(){int index = 0;byte[] bytes = new byte[GetBytesNum()];WriteString(bytes, name, ref index);WriteInt(bytes, lev, ref index);WriteInt(bytes, atk, ref index);return bytes;}
}

这段代码定义了一个名为PlayerData的类，它继承自BaseData类。PlayerData类的作用是用来表示玩家的相关数据，并且实现了这些数据的序列化与反序列化功能。

服务端类

这段代码定义了一个名为ServerSocket的类，用于构建基于 UDP 协议的服务器，它能通过绑定指定 IP 和端口启动服务，利用线程池实现消息接收与客户端超时检查，将客户端信息存储在字典中，可处理新客户端连接，接收客户端消息并交予对应客户端对象处理，支持向指定客户端发送消息、向所有客户端广播消息，还能移除超时或指定的客户端。

using System;
using System.Collections.Generic;
using System.Linq;
using System.Net;
using System.Net.Sockets;
using System.Text;
using System.Threading;
using System.Threading.Tasks;namespace UDPServerExerise
{class ServerSocket{public Socket socket;private bool IsClose;//我们可以通过记录谁给我们发了消息 把它的IP和端口记录下来 这样就认为他是我的客户端了private Dictionary<string, Client> clientDic = new Dictionary<string, Client>();public void Start(string ip,int port){socket = new Socket(AddressFamily.InterNetwork, SocketType.Dgram, ProtocolType.Udp);IPEndPoint ipPoint = new IPEndPoint(IPAddress.Parse(ip), port);try{socket.Bind(ipPoint);IsClose = false;}catch (Exception e){Console.WriteLine("UDP开启错误" + e.Message);}//接收消息，使用线程池ThreadPool.QueueUserWorkItem(ReceiveMsg);//检测超时的线程ThreadPool.QueueUserWorkItem(CheakTimeOut);}private void CheakTimeOut(object obj){long nowTime=0;List<string> delClient = new List<string>();while (true){//30秒检查一次Thread.Sleep(30000);//得到当前系统时间nowTime = DateTime.Now.Ticks / TimeSpan.TicksPerSecond;foreach (Client c in clientDic .Values){//超过十秒没有 收到消息的客户端需要被移除if(nowTime -c.frontTime >=10){delClient.Add(c.clientID);}}//从待删除列表中删除超时客户端for (int i = 0; i < delClient.Count; i++)RemoveClient(delClient[i]);delClient.Clear();}}private void ReceiveMsg(object obj){byte[] bytes = new byte[512];//记录谁发的string strID = "";string ip;int port;EndPoint ipPoint = new IPEndPoint(IPAddress.Any, 0);while (!IsClose){if(socket.Available >0){lock(socket)socket.ReceiveFrom(bytes, ref ipPoint);//处理消息 最好不要直接在这里处理，而是交给客户端对象处理//收到消息时，我们要判断 是不是记录了这个客户端的信息(ip和端口)//出去发送消息给我的IP和端口ip = (ipPoint as IPEndPoint).Address.ToString();port = (ipPoint as IPEndPoint).Port;strID = ip + port;//拼接成唯一一个ID这是我们自定义的规则//判断有没有记录这个客户端的信息，如果有直接用它处理信息if(clientDic .ContainsKey (strID )){clientDic[strID].ReceiveMsg(bytes);}else//如果没有 直接添加并处理消息{clientDic.Add(strID, new Client(ip, port));clientDic[strID].ReceiveMsg(bytes);}}}}public void SendTo(BaseMsg msg,IPEndPoint ipPoint){try{lock (socket)socket.SendTo(msg.Writing(), ipPoint);}catch (SocketException s){Console.WriteLine("发消息出现问题" + s.SocketErrorCode + s.Message);}catch (Exception e){Console.WriteLine("发消息出现问题(可能是序列化的问题)" + e.Message);}}private void Close(){if(socket!=null){socket.Shutdown(SocketShutdown.Both);socket.Close();IsClose = true;socket = null;}}public void BoardCast(BaseMsg msg){//广播给谁foreach (Client c in clientDic .Values){SendTo(msg,c.ipAndPoint);}}public void RemoveClient(string clientID){if(clientDic .ContainsKey (clientID)){Console.WriteLine("客户端{0}被移除了", clientID);clientDic.Remove(clientID);}}}
}

客户端类

这段代码定义了Client类，用于处理 UDP 服务器端接收到的来自客户端的消息。Client类的构造函数通过传入的 IP 和端口创建IPEndPoint对象并生成唯一的客户端 ID；ReceiveMsg方法接收消息字节数组，拷贝消息到新数组，记录消息接收时间，并将消息处理任务放入线程池；ReceiceHandleMsg方法从消息字节数组中解析消息类型、长度和消息体，针对不同消息 ID（如 1001 对应PlayerMsg消息，1003 对应quitMsg消息）进行相应处理，如反序列化PlayerMsg并输出相关信息，处理quitMsg时移除对应客户端，若处理消息出错也会移除该客户端。

using System;
using System.Collections.Generic;
using System.Linq;
using System.Net;
using System.Text;
using System.Threading;
using System.Threading.Tasks;namespace UDPServerExerise
{class Client{public IPEndPoint ipAndPoint;public string clientID;public float frontTime = -1;public Client (string ip,int port){//规则和外边一样 记录唯一ID 通过ip和port拼接的形式clientID = ip + port;//把客户端的信息记录下来ipAndPoint = new IPEndPoint(IPAddress.Parse(ip), port);}public void ReceiveMsg(byte[]bytes){//为了避免处理消息时又接收到了新的消息 所以我们需要在处理消息前 先把消息拷贝出来//处理消息和接收消息用不同容器 避免发生冲突byte[] cacheBytes = new byte[512];bytes.CopyTo(cacheBytes, 0);//记录发消息的系统时间frontTime = DateTime.Now.Ticks / TimeSpan.TicksPerSecond;ThreadPool.QueueUserWorkItem(ReceiceHandleMsg, cacheBytes);}private void ReceiceHandleMsg(object obj){try{byte[] bytes = obj as byte[];int nowIndex = 0;//解析消息类型int msgID = BitConverter.ToInt32(bytes, nowIndex);nowIndex += 4;//解析消息长度int length = BitConverter.ToInt32(bytes, nowIndex);nowIndex += 4;//解析消息体switch (msgID){case 1001:PlayerMsg playerMsg = new PlayerMsg();playerMsg.Reading(bytes, nowIndex);Console.WriteLine(playerMsg.playerID);Console.WriteLine(playerMsg.playerData.lev);Console.WriteLine(playerMsg.playerData.atk);Console.WriteLine(playerMsg.playerData.name);break;case 1003:quitMsg quitMsg = new quitMsg();//由于它没有消息体 所以不用反序列化//quitMsg.Reading(bytes, nowIndex);//处理退出Program.serverSocket.RemoveClient(clientID);break;}}catch (Exception e){Console.WriteLine("处理消息出错" + e.Message);//如果出错了，就不用记录客户端的信息了Program.serverSocket.RemoveClient(clientID);}}}
}

退出消息类

这段代码定义了一个名为quitMsg的类，它继承自BaseMsg类，用于表示退出消息，重写了GetBytesNum方法指定消息字节数为 8，重写GetID方法返回消息唯一标识符 1003，重写Reading方法调用基类方法进行反序列化，重写Writing方法将消息 ID 和消息体长度（这里设为 0）序列化为字节数组。

using System.Collections;
using System.Collections.Generic;public class quitMsg : BaseMsg
{public override int GetBytesNum(){return 8;}public override int GetID(){return 1003;}public override int Reading(byte[] bytes, int beginIndex = 0){return base.Reading(bytes, beginIndex);}public override byte[] Writing(){int index = 0;byte[] bytes = new byte[GetBytesNum()];WriteInt(bytes, GetID(), ref index);WriteInt(bytes, 0, ref index);return bytes;}
}

主函数启动服务器

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading.Tasks;namespace UDPServerExerise
{class Program{public static ServerSocket serverSocket;static void Main(string[] args){serverSocket = new ServerSocket();serverSocket.Start("127.0.0.1", 8080);Console.WriteLine("UDP服务器启动了");string input = Console.ReadLine();if(input.Substring (0,2)=="B:"){PlayerMsg msg = new PlayerMsg();msg.playerData = new PlayerData();msg.playerID = 1001;msg.playerData.atk = 999;msg.playerData.lev = 88;msg.playerData.name ="DamnF的服务器";serverSocket.BoardCast(msg);}}}
}