NET7下用WebSocket做简易聊天室

步骤：

建立NET7的MVC视图模型控制器项目
创建websocket之间通信的JSON字符串对应的实体类
一个房间用同一个Websocket
websocket集合类，N个房间
创建websocket中间件代码
Program.cs中的核心代码，使用Websocket
聊天室HTML页面代码

参考文章：.NET Core中WebSocket的使用详解_.net websocket-CSDN博客

GIT源码地址：公开仓库（里面还有以前做的.NET FRAMEWORK的websocket示例代码）

建立NET7的MVC视图模型控制器项目

创建websocket之间通信的JSON字符串对应的实体类

namespace NetCore.WebSocketDemo.Models
{/// <summary>/// websocket之间通信的JSON字符串转的实体类/// </summary>public class Message{/// <summary>/// websocket对应的ID/// </summary>public string SendClientId { set; get; }/// <summary>/// 加入房间join 发送消息send_to_room 离开房间levea/// </summary>public string action { set; get; }/// <summary>/// 房间号/// </summary>public string roomNo { set; get; }/// <summary>/// 昵称/// </summary>public string nick { set; get; }/// <summary>/// 发送的消息内容 /// </summary>public string msg { set; get; }}
}

一个房间用同一个Websocket

using System.Net.Sockets;
using System.Net.WebSockets;
using System.Text;namespace NetCore.WebSocketDemo.Models
{/// <summary>/// 一个房间里的都用这个websocket/// </summary>public class WebsocketClient{public string Id { set; get; }public string RoomNo { set; get; }public WebSocket WebSocket { set; get; }public async Task SendMessageAsync(string text){var recvBytes = Encoding.UTF8.GetBytes(text);var sendBuffer = new ArraySegment<byte>(recvBytes);try{await WebSocket.SendAsync(sendBuffer, WebSocketMessageType.Text, true, CancellationToken.None);}catch (Exception ex){throw ex;} }}
}

websocket集合类，N个房间

namespace NetCore.WebSocketDemo.Models
{/// <summary>/// websocket集合类，N个房间/// </summary>public class WebsocketClientCollection{private static List<WebsocketClient> _clients = new List<WebsocketClient>();public static void Add(WebsocketClient client){_clients.Add(client);}public static void Remove(WebsocketClient client){_clients.Remove(client);}public static WebsocketClient Get(string clientId){var client = _clients.FirstOrDefault(c => c.Id == clientId);return client;}public static List<WebsocketClient> GetAll(){return _clients;}public static List<WebsocketClient> GetClientsByRoomNo(string roomNo){var client = _clients.Where(c => c.RoomNo == roomNo);return client.ToList();}}
}

创建websocket中间件代码

using Newtonsoft.Json;
using System.Net.WebSockets;
using System.Text;namespace NetCore.WebSocketDemo.Models
{/// <summary>/// programe里用 app.UseWebsocketHandlerMiddleware();/// </summary>public static class WebsocketHandlerMiddlewareExtensions{public static IApplicationBuilder UseWebsocketHandlerMiddleware(this IApplicationBuilder builder){return builder.UseMiddleware<WebsocketHandlerMiddleware>();}}/// <summary>/// websocket中间件/// </summary>public class WebsocketHandlerMiddleware  {private readonly RequestDelegate _next;public WebsocketHandlerMiddleware(  RequestDelegate next){_next = next;} public async Task InvokeAsync(HttpContext context){if (context.Request.Path == "/ws"){//仅当网页执行new WebSocket("ws://localhost:5000/ws")时，后台会执行此逻辑if (context.WebSockets.IsWebSocketRequest){//后台成功接收到连接请求并建立连接后，前台的webSocket.onopen = function (event){}才执行WebSocket webSocket = await context.WebSockets.AcceptWebSocketAsync();string clientId = Guid.NewGuid().ToString(); ;var wsClient = new WebsocketClient{Id = clientId,WebSocket = webSocket};try{await Handle(wsClient);}catch (Exception ex){await context.Response.WriteAsync("closed");}}else{context.Response.StatusCode = 404;}}else{await _next(context);}}private async Task Handle(WebsocketClient websocketClient){WebsocketClientCollection.Add(websocketClient);WebSocketReceiveResult clientData = null;do{var buffer = new byte[1024 * 1];//客户端与服务器成功建立连接后，服务器会循环异步接收客户端发送的消息，收到消息后就会执行Handle(WebsocketClient websocketClient)中的do{}while;直到客户端断开连接//不同的客户端向服务器发送消息后台执行do{}while;时，websocketClient实参是不同的，它与客户端一一对应//同一个客户端向服务器多次发送消息后台执行do{}while;时，websocketClient实参是相同的clientData = await websocketClient.WebSocket.ReceiveAsync(new ArraySegment<byte>(buffer), CancellationToken.None);if (clientData.MessageType == WebSocketMessageType.Text && !clientData.CloseStatus.HasValue){var msgString = Encoding.UTF8.GetString(buffer);var message = JsonConvert.DeserializeObject<Message>(msgString);message.SendClientId = websocketClient.Id;HandleMessage(message);}} while (!clientData.CloseStatus.HasValue);//关掉使用WebSocket连接的网页/调用webSocket.close()后，与之对应的后台会跳出循环WebsocketClientCollection.Remove(websocketClient);}private void HandleMessage(Message message){var client = WebsocketClientCollection.Get(message.SendClientId);switch (message.action){case "join":client.RoomNo = message.roomNo;client.SendMessageAsync($"{message.nick} join room {client.RoomNo} success .");break;case "send_to_room":if (string.IsNullOrEmpty(client.RoomNo)){break;}var clients = WebsocketClientCollection.GetClientsByRoomNo(client.RoomNo);clients.ForEach(c =>{c.SendMessageAsync(message.nick + " : " + message.msg);});break;case "leave":#region 通过把连接的RoomNo置空模拟关闭连接var roomNo = client.RoomNo;client.RoomNo = "";#endregion#region 后台关闭连接//client.WebSocket.CloseAsync(WebSocketCloseStatus.NormalClosure, "", CancellationToken.None);//WebsocketClientCollection.Remove(client); #endregionclient.SendMessageAsync($"{message.nick} leave room {roomNo} success .");break;default:break;}}}
}

Program.cs中的核心代码，使用Websocket

var app = builder.Build();#region 配置中间件，使用websocketapp.UseWebSockets(new WebSocketOptions{KeepAliveInterval = TimeSpan.FromSeconds(60),ReceiveBufferSize = 1 * 1024});app.UseWebsocketHandlerMiddleware(); #endregion

聊天室HTML页面代码

<!DOCTYPE html>
<html>
<head><meta charset="utf-8" /><title>简易websocket聊天室应用</title>
</head>
<body><div style="margin-bottom:5px;">房间号: <input type="text" id="txtRoomNo" value="99999" /><button id="btnJoin">加入房间</button><button id="btnLeave">离开房间</button><button id="btnDisConnect">断开链接</button></div><div style="margin-bottom:5px;">我的昵称: <input type="text" id="txtNickName" value="niunan" /></div><div style="height:300px;width:600px"><textarea style="height:100%;width:100%" id="msgList"></textarea><div style="text-align: right"><input type="text" id="txtMsg" value="" placeholder="请输入您要发送的文本消息" />  <button id="btnSend">发送</button></div></div><script src="lib/jquery/dist/jquery.min.js"></script><script>var webSocket = new WebSocket("ws://localhost:5160/ws");//前台向后台发送连接请求，后台成功接收并建立连接后才会触发此事件webSocket.onopen = function (event) {console.log("Connection opened...");$("#msgList").val("WebSocket connection opened");};//后台向前台发送消息，前台成功接收后会触发此事件webSocket.onmessage = function (event) {console.log("Received message: " + event.data);if (event.data) {var content = $('#msgList').val();content = content + '\r\n' + event.data;$('#msgList').val(content);}};//后台关闭连接后/前台关闭连接后都会触发此事件webSocket.onclose = function (event) {console.log("Connection closed...");var content = $('#msgList').val();content = content + '\r\nWebSocket connection closed';$('#msgList').val(content);};$('#btnJoin').on('click', function () {var roomNo = $('#txtRoomNo').val();var nick = $('#txtNickName').val();if (!roomNo) {alert("请输入RoomNo");return;}var msg = {action: 'join',roomNo: roomNo,nick: nick};if (CheckWebSocketConnected(webSocket)) {webSocket.send(JSON.stringify(msg));}});$('#btnSend').on('click', function () {var message = $('#txtMsg').val();var nick = $('#txtNickName').val();if (!message) {alert("请输入发生的内容");return;}if (CheckWebSocketConnected(webSocket)) {webSocket.send(JSON.stringify({action: 'send_to_room',msg: message,nick: nick}));}});$('#btnLeave').on('click', function () {var nick = $('#txtNickName').val();var msg = {action: 'leave',roomNo: '',nick: nick};if (CheckWebSocketConnected(webSocket)) {webSocket.send(JSON.stringify(msg));}});$("#btnDisConnect").on("click", function () {if (CheckWebSocketConnected(webSocket)) {//部分浏览器调用close()方法关闭WebSocket时不支持传参//webSocket.close(001, "closeReason");webSocket.close();}});//判断当前websocket的状态/*CONNECTING：值为0，表示正在连接。OPEN：值为1，表示连接成功，可以通信。CLOSING：值为2，表示连接正在关闭。CLOSED：值为3，表示连接已经关闭，或者打开连接失败。*/function CheckWebSocketConnected(ws) {var b = false;switch (ws.readyState) {case WebSocket.CONNECTING:    // 也可以用0// do somethingbreak;case WebSocket.OPEN:            // 也可以用1// do somethingb = true;break;case WebSocket.CLOSING:        // 也可以用2// do somethingbreak;case WebSocket.CLOSED:        // 也可以用3// do somethingbreak;default:// this never happensbreak;}return b;}</script>
</body>
</html>