C#实现本地服务器客户端私聊通信

（一）需求

       在游戏中我们经常能够看到玩家与玩家之间可以进行私聊，在QQ或微信中最基本的功能就是用户与用户之间的通信。抽象成计算机网络，就是两个客户端通过服务器进行私聊通信，两个客户端可以互相看到对方发送过来的信息。这种两个客户端的私聊通信是如何实现的呢？在本篇文章我们就来探讨一下。

（二）解决思路

       这个需求的重点部分在于网络通信，需要我们掌握基本的计算机网络通信知识，具体到每种编程语言又有对应的API。如果把这个需求抽象到计算机网络中，我们就可以理解成两个客户端向服务器发送信息，服务器接收信息后又把信息发送给另一个客户端。这样，一个客户端就可以接收到另一个客户端发送的信息了。

（三）设计思路

       服务器基于本地服务器开发，通过一个单独的C#控制台项目模拟，编程语言使用C#，客户端通过Unity3D构建GUI并编写客户端脚本。两个客户端则通过打开两个Unity3D项目的可执行文件进行模拟，客户端的GUI需要有调试面板、客户端名称下拉菜单、连接和断开连接按钮、消息显示面板、消息输入框和消息发送按钮等。

（四）代码实现

        由于代码中引用了自定义的网络通信共享库NetShare，关于NetShare请阅读这篇文章。

---

       客户端

using System;
using System.Collections.Generic;
using System.Net;
using System.Net.Sockets;
using UnityEngine;
using UnityEngine.UI;
/*
自定义网络通信共享库NetShare，包括通用数据包DataPacket、私聊频道服务器数据包PSDataPacket、
服务器数据包ServerDataPacket和私聊频道客户端数据包PCDataPacket等。
*/
using NetShare;
using System.Threading;
using System.Linq;

//私聊频道客户端
public class PersonalChannelClient : MonoBehaviour
{
    public Text BaseInfo;//显示Socket连接基本信息的文本
    public Text EchoContents;//Socket回显信息的文本
    public Text ChatContents;//聊天信息的文本
    public Dropdown Friends;//目标客户端名称下拉菜单
    public Dropdown ClientMenu;//客户端名称下拉菜单
    public Button Connect;//连接按钮
    public Button DisConnect;//断开连接按钮
    public InputField SendInput;//聊天消息输入框
    public Button Send;//聊天信息发送按钮

    static string ipAddressStr;//IP地址字符串
    static int port;//端口
    static IPAddress iPAddress;//IP地址对象
    static IPEndPoint iPEndPoint;//IP端点对象
    string clientName, sendStr;//客户端名称和发送信息字符串
    Socket currentClientSocket;//当前客户端Socket
    bool isLockSend;//是否锁定聊天信息发送按钮
    byte[] buffer;//消息接收缓冲区
    Queue echoContentQueue, chatContentQueue;//回显信息队列和聊天信息队列
    PCDataPacket dataPacket;//通用数据包
    List desClientNames;//目标客户端名称合集

    //反映Socket是否与服务器有效连接的属性
    bool isConnected
    {
        get
        {
            if (currentClientSocket == null) return false;
            return !currentClientSocket.Poll(10, SelectMode.SelectRead) && currentClientSocket.Connected;
        }
    }

    void Start()
    {
        //初始化
        ipAddressStr = "127.0.0.1";
        clientName = ClientMenu.options.Count > 0 ? ClientMenu.options[0].text : "";
        port = 5500;
        iPAddress = IPAddress.Parse(ipAddressStr);
        iPEndPoint = new IPEndPoint(iPAddress, port);
        buffer = new byte[1024];
        echoContentQueue = new Queue();
        chatContentQueue = new Queue();
        desClientNames = new List() { "None" };

        //为UI控件添加监听事件
        ClientMenu.onValueChanged.AddListener((index) =>
        {
            clientName = ClientMenu.options[index].text;
        });
        Connect.onClick.AddListener(() =>
        {
            Thread thread = new Thread(new ThreadStart(ConnectDeal));
            thread.Start();
        });
        DisConnect.onClick.AddListener(() =>
        {
            Thread thread = new Thread(new ThreadStart(DisConnectDeal));
            thread.Start();
        });
        Send.onClick.AddListener(() =>
        {
            sendStr = SendInput.text;
            Thread thread = new Thread(new ThreadStart(SendDeal));
            thread.Start();
            SendInput.text = string.Empty;
        });
    }

    void Update()
    {
        //不断更新Socket基本信息
        BaseInfo.text = $"ClientName:{clientName}" +
                        string.Format("\nSocketHashCode:{0}", currentClientSocket == null ? "None" : currentClientSocket.GetHashCode().ToString()) +
                        $"\nisLock:{isLockSend}" +
                        string.Format("\nPoll:{0}", currentClientSocket == null ? "None" : (!currentClientSocket.Poll(10, SelectMode.SelectRead)).ToString()) +
                        string.Format("\nIsConnected:{0}", currentClientSocket == null ? "False" : currentClientSocket.Connected.ToString());
        //更新回显信息
        if (echoContentQueue.Count > 0)
        {
            while (echoContentQueue.Count > 0)
            {
                SetEchoContents(echoContentQueue.Dequeue());
            }
        }
        //更新聊天信息
        if (chatContentQueue.Count > 0)
        {
            while (chatContentQueue.Count > 0)
            {
                SetChatContents(chatContentQueue.Dequeue());
            }
        }
        //更新目标客户端名称下拉菜单
        if (desClientNames?.Count > 0)
        {
            Friends.AddOptions(desClientNames);
            desClientNames.Clear();
        }
    }

    //设置回显信息相关UI的内容
    void SetEchoContents(string text)
    {
        EchoContents.text += text;
    }

    //设置聊天信息相关UI的内容
    void SetChatContents(string text)
    {
        ChatContents.text += text;
    }

    //执行逻辑：Socket异步连接处理
    void ConnectDeal()
    {
        echoContentQueue.Enqueue($"\n客户端{clientName}正在请求服务器连接...");
        Socket clientSocket = new Socket(AddressFamily.InterNetwork, SocketType.Stream, ProtocolType.Tcp);
        clientSocket.BeginConnect(iPEndPoint, ConnectCallback, clientSocket);
    }

    //执行逻辑：Socket异步断开连接处理
    void DisConnectDeal()
    {
        echoContentQueue.Enqueue($"\n客户端{clientName}正在断开与服务器的连接...");
        if (isConnected)
        {
            currentClientSocket.Shutdown(SocketShutdown.Both);
            currentClientSocket.BeginDisconnect(false, DisConnectCallback, currentClientSocket);
        }
        else echoContentQueue.Enqueue($"\n客户端{clientName}未与服务器建立连接,无法进行断开连接的操作...");
    }

    //执行逻辑：Socket异步接收信息处理
    void ReceiveDeal()
    {
        echoContentQueue.Enqueue($"\n客户端{clientName}开始监听服务器响应...");
        currentClientSocket.BeginReceive(buffer, 0, buffer.Length, SocketFlags.None, ReceiveCallback, currentClientSocket);
    }

    //执行逻辑：Socket异步发送信息处理
    void SendDeal()
    {
        if (!isLockSend && !string.IsNullOrEmpty(sendStr))
        {
            dataPacket.mContent = sendStr;
            string v_desClientName = Friends.options[Friends.value].text;
            if (!v_desClientName.Equals("None")) dataPacket.mDestinationClientName = v_desClientName;
            byte[] bytes = dataPacket.ToBytes();
            currentClientSocket.BeginSend(bytes, 0, bytes.Length, SocketFlags.None, SendCallback, currentClientSocket);
        }
    }

    //执行逻辑：Socket异步连接处理回调
    void ConnectCallback(IAsyncResult ar)
    {
        try
        {
            Socket socket = ar.AsyncState as Socket;
            socket.EndConnect(ar);
            currentClientSocket = socket;
            if (isConnected)
            {
                dataPacket = new PCDataPacket()
                {
                    mLocalEndPointStr = socket.LocalEndPoint.ToString(),
                    mClientName = clientName,
                    mDestinationClientName = string.Empty,
                    mContent = $"成功与服务器建立连接!"
                };
                byte[] bytes = dataPacket.ToBytes();
                socket.BeginSend(bytes, 0, bytes.Length, SocketFlags.None, SendCallback, currentClientSocket);
                isLockSend = false;
                echoContentQueue.Enqueue($"\n客户端{clientName}与服务器连接成功!");
                ReceiveDeal();
            }
            else echoContentQueue.Enqueue($"\n客户端{clientName}与服务器连接失败!");
        }
        catch (SocketException se)
        {
            echoContentQueue.Enqueue($"\n客户端{clientName}与服务器连接失败!\n错误信息:{se.Message}");
        }
    }

    //执行逻辑：Socket异步断开连接处理回调
    void DisConnectCallback(IAsyncResult ar)
    {
        try
        {
            isLockSend = true;
            Socket socket = ar.AsyncState as Socket;
            socket.EndDisconnect(ar);
            dataPacket = null;
            echoContentQueue.Enqueue($"\n客户端{clientName}与服务器断开连接操作成功!");
        }
        catch (SocketException se)
        {
            echoContentQueue.Enqueue($"\n客户端{clientName}与服务器断开连接操作失败！\n错误信息:{se.Message}");
        }
    }

    //执行逻辑：Socket异步发送信息处理回调
    void SendCallback(IAsyncResult ar)
    {
        try
        {
            Socket socket = ar.AsyncState as Socket;
            socket.EndSend(ar);
            echoContentQueue.Enqueue($"\n客户端{clientName}向服务器发送了一条消息！");
        }
        catch (SocketException se)
        {
            echoContentQueue.Enqueue($"\n客户端{clientName}向服务器发送信息操作失败！\n错误信息:{se.Message}");
        }
    }

    //执行逻辑：Socket异步接收信息处理回调
    void ReceiveCallback(IAsyncResult ar)
    {
        try
        {
            Socket socket = ar.AsyncState as Socket;
            int count = socket.EndReceive(ar);
            DataPacket dataPacket = DataPacket.ToObject(buffer.Take(count).ToArray());
            if (dataPacket is PSDataPacket psdp && psdp.mClientNames?.Length > 0)
            {
                desClientNames.Clear();
                foreach (string name in psdp.mClientNames)
                {
                    if (Friends.options.FindIndex((od) => od.text.Equals(name)) == -1) desClientNames.Add(name);
                }
            }
            else if (dataPacket is ServerDataPacket sdp)
            {
                string v_res = sdp.mContent;
                if (!string.IsNullOrEmpty(v_res)) chatContentQueue.Enqueue("\n" + v_res);
            }
            //若Socket连接有效则继续接收消息
            if (isConnected)
                socket.BeginReceive(buffer, 0, buffer.Length, SocketFlags.None, ReceiveCallback, socket);
        }
        catch (SocketException se)
        {
            echoContentQueue.Enqueue($"\n客户端{clientName}接收服务器消息失败！\n错误信息:{se.Message}");
        }
    }
}

---

        服务器

using System.Net.Sockets;
using System.Net;

/*
自定义网络通信共享库NetShare，其中包括了私聊频道服务器数据包PSDataPacket、通用数据包DataPacket、
服务器数据包ServerDataPacket和私聊频道客户端数据包PCDataPacket等。
 */

using NetShare;

namespace UnityServer
{
    //私聊频道服务器
    internal class PersonalChannelServer
    {
        private static string ipAddress = "127.0.0.1";//IP地址字符串
        private static int port = 5500;//端口
        private static int maxConnect = 20;//最大连接数
        private static byte[] buffer = new byte[1024];//消息缓冲区

        //客户端Socket合集，key为IPEndPoint字符串，value为服务器为客户端分配的Socket
        private static Dictionary clients = new Dictionary();

        private static Socket? serverSocket;//服务器Socket

        //客户端键值对，key为客户端名称，value为IPEndPoint字符串
        private static Dictionary clientKVs = new Dictionary();

        private static void Main(string[] args)
        {
            Thread thread = new Thread(new ThreadStart(ServerDeal));
            thread.Start();
            Console.ReadLine();
        }

        //判断Socket是否进行有效连接
        private static bool IsConnected(Socket socket)
        {
            if (socket == null) return false;
            return !socket.Poll(10, SelectMode.SelectRead) && socket.Connected;
        }

        //执行逻辑：服务器处理
        private static void ServerDeal()
        {
            serverSocket = new Socket(AddressFamily.InterNetwork, SocketType.Stream, ProtocolType.Tcp);
            IPAddress v_ipAddress = IPAddress.Parse(ipAddress);
            serverSocket.Bind(new IPEndPoint(v_ipAddress, port));
            serverSocket.Listen(maxConnect);
            Console.WriteLine($"开启服务器[{serverSocket.LocalEndPoint}]...");

            serverSocket.BeginAccept(AcceptCallback, null);
        }

        //执行逻辑：Socket异步接收消息
        private static void ReceiveDeal(object? clientSocket)
        {
            Console.WriteLine("********************");
            if (clientSocket == null) return;
            Socket? v_clientSocket = clientSocket as Socket;
            if (v_clientSocket == null) return;
            Console.WriteLine("接收到客户端的连接请求！");

            if (IsConnected(v_clientSocket))
                v_clientSocket.BeginReceive(buffer, 0, buffer.Length, SocketFlags.None, ReceiveCallback, v_clientSocket);
        }

        //添加客户端Socket到客户端Socket合集
        private static void AddClient(Socket clientSocket)
        {
            if (clientSocket == null) return;
            EndPoint? endPoint = clientSocket.RemoteEndPoint;
            if (endPoint != null)
            {
                string? v_endPointStr = endPoint.ToString();
                if (v_endPointStr != null) clients[v_endPointStr] = clientSocket;
            }
        }

        //向所有客户端发送指定信息
        private static void SendToAll(PSDataPacket dataPacket)
        {
            if (dataPacket == null) return;
            byte[] bytes = dataPacket.ToBytes();
            foreach (Socket clientSocket in clients.Values)
            {
                if (IsConnected(clientSocket))
                {
                    Thread thread = new Thread(() =>
                    {
                        clientSocket.BeginSend(bytes, 0, bytes.Length, SocketFlags.None, SendCallback, clientSocket);
                    });
                    thread.Start();
                }
            }
        }

        //向指定的客户端发送服务器数据包
        private static void SendTo(ServerDataPacket dataPacket, Socket? destinationSocket)
        {
            if (dataPacket == null || destinationSocket == null) return;
            byte[] bytes = dataPacket.ToBytes();
            if (IsConnected(destinationSocket))
            {
                Thread thread = new Thread(() =>
                {
                    destinationSocket.BeginSend(bytes, 0, bytes.Length, SocketFlags.None, SendCallback, destinationSocket);
                });
                thread.Start();
            }
        }

        //Socket监听请求回调
        private static void AcceptCallback(IAsyncResult ar)
        {
            try
            {
                if (serverSocket != null)
                {
                    Socket clientSocket = serverSocket.EndAccept(ar);
                    AddClient(clientSocket);
                    Thread thread = new Thread(new ParameterizedThreadStart(ReceiveDeal));
                    thread.Start(clientSocket);
                    serverSocket.BeginAccept(AcceptCallback, null);
                }
            }
            catch (SocketException se)
            {
                Console.WriteLine("AcceptException:" + se.Message);
            }
        }

        //Socket发送信息回调
        private static void SendCallback(IAsyncResult ar)
        {
            try
            {
                Socket? clientSocket = ar.AsyncState as Socket;
                if (clientSocket != null) clientSocket.EndSend(ar);
            }
            catch (SocketException se)
            {
                Console.WriteLine("SendException:" + se.Message);
            }
        }

        //Socket接收信息回调
        private static void ReceiveCallback(IAsyncResult ar)
        {
            try
            {
                Socket? clientSocket = ar.AsyncState as Socket;
                if (clientSocket != null)
                {
                    int bytesCount = clientSocket.EndReceive(ar);
                    PCDataPacket? dataPacket = DataPacket.ToObject(buffer.Take(bytesCount).ToArray());
                    if (dataPacket != null)
                    {
                        if (clientSocket.RemoteEndPoint != null)
                        {
                            string? v_endPointStr = clientSocket.RemoteEndPoint.ToString();
                            if (!string.IsNullOrEmpty(v_endPointStr))
                            {
                                clientKVs[dataPacket.mClientName] = v_endPointStr;
                                SendToAll(new PSDataPacket()
                                {
                                    mClientNames = clientKVs.Keys.ToArray()
                                });
                            }
                        }
                        string v_content = $"客户端{dataPacket.mClientName}：{dataPacket.mContent}";
                        Socket? destinationSocket;
                        string? endPointStr;
                        clientKVs.TryGetValue(dataPacket.mDestinationClientName, out endPointStr);
                        if (!string.IsNullOrEmpty(endPointStr) && clients.TryGetValue(endPointStr, out destinationSocket))
                            SendTo(new ServerDataPacket() { mContent = v_content }, destinationSocket);
                    }
                    if (IsConnected(clientSocket))
                        clientSocket.BeginReceive(buffer, 0, buffer.Length, SocketFlags.None, ReceiveCallback, clientSocket);
                }
            }
            catch (SocketException se)
            {
                Console.WriteLine("ReceiveException:" + se.Message);
            }
        }
    }
}

（五）测试

       测试流程大概是先启动服务器，然后启动三个客户端，三个客户端分别以A、B、C的名称作为客户端名称与服务器建立连接，连接后再由客户端A、B、C分别向服务器发送信息，通过观察三个客户端的消息面板来确定测试结果，这里之所以启动三个客户端是为了进行对比测试，以区分多客户端的同频道通信，具体测试流程请观看下列视频：

本地服务器客户端单独通信

（六）总结

       在服务器端，我们通过一个C#控制台项目来模拟服务器后台，服务器与客户端具有类似的功能，同样具有发送、接收消息的功能，不同的是服务器具有监听客户端连接的功能，而客户端具有向服务器发送连接请求的功能，本质上这些都是通过Socket实现的功能，人为划分成服务器端和客户端。在客户端我们通过GUI将用户的操作进行可视化构建，实现了回显、客户端名称选择、连接、断开连接、发送和显示消息等基本交互。

       为了模拟多客户端并发操作，所有功能我们都采用了异步的方式启动，对于真正的网络通信而言，这对我们来说才刚刚开始，不过通过这个案例也让我们了解了基本的网络通信流程。

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