介紹
我喜歡.NET CORE 這個東西，其實不僅僅源于它性能很高，可以跨平臺，還因為它的設計模式確實令人著迷。以前沒.NET CORE 的時候，.NET用websocket必須跑在windows server 2012上，但我一般不會這么干，都把websocket架在nodejs的服務器上。這么分出來，麻煩肯定是麻煩的，而且js這東西，寫復雜和幾年后再看都是頭疼的問題。那么，如果.NET CORE是以kestrel運行的，那么就不再需要考慮服務器的版本運行，任何一個地方都可以用websocket
ASP.NET Core SignalR是一個有用的庫，可以簡化Web應用程序中實時通信的管理。但是，我寧愿使用WebSockets，因為我想要更靈活，并且與任何WebSocket客戶端兼容。
在Microsoft的文檔中，我找到了一個很好的WebSockets工作示例。它仍然是管理連接，以便能夠從一個連接向其他連接廣播消息，這是SignalR開箱即用的功能。期望這個邏輯非常復雜，我想從Startup類中刪除它。
背景
要閱讀ASP.NET Core中的WebSockets支持，可以在此處查看。如果您想了解中間件以及如何在ASP.NET Core中編寫它，請閱讀此鏈接。
代碼使用
首先，你必須添加 Microsoft.AspNetCore.WebSockets 包到你的項目。
現在，您可以創建一個擴展方法和類來管理WebSockets：
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public static class WebSocketExtensions{ public static IApplicationBuilder UseCustomWebSocketManager(this IApplicationBuilder app) { return app.UseMiddleware<CustomWebSocketManager>(); }}public class CustomWebSocketManager{ private readonly RequestDelegate _next; public CustomWebSocketManager(RequestDelegate next) { _next = next; } public async Task Invoke(HttpContext context, ICustomWebSocketFactory wsFactory, ICustomWebSocketMessageHandler wsmHandler) { if (context.Request.Path == "/ws") { if (context.WebSockets.IsWebSocketRequest) { string username = context.Request.Query["u"]; if (!string.IsNullOrEmpty(username)) { WebSocket webSocket = await context.WebSockets.AcceptWebSocketAsync(); CustomWebSocket userWebSocket = new CustomWebSocket() { WebSocket = webSocket, Username = username }; wsFactory.Add(userWebSocket); await wsmHandler.SendInitialMessages(userWebSocket); await Listen(context, userWebSocket, wsFactory, wsmHandler); } } else { context.Response.StatusCode = 400; } } await _next(context); } private async Task Listen(HttpContext context, CustomWebSocket userWebSocket, ICustomWebSocketFactory wsFactory, ICustomWebSocketMessageHandler wsmHandler) { WebSocket webSocket = userWebSocket.WebSocket; var buffer = new byte[1024 * 4]; WebSocketReceiveResult result = await webSocket.ReceiveAsync(new ArraySegment<byte>(buffer), CancellationToken.None); while (!result.CloseStatus.HasValue) { await wsmHandler.HandleMessage(result, buffer, userWebSocket, wsFactory); buffer = new byte[1024 * 4]; result = await webSocket.ReceiveAsync(new ArraySegment<byte>(buffer), CancellationToken.None); } wsFactory.Remove(userWebSocket.Username); await webSocket.CloseAsync(result.CloseStatus.Value, result.CloseStatusDescription, CancellationToken.None); }} |
在這種情況下，WebSockets請求在URL中始終包含“/ ws”。查詢字符串包含用于將WebSocket與登錄用戶相關聯的用戶名的參數u。
CustomWebSocket是一個包含WebSocket和用戶名的類：
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public class CustomWebSocket{ public WebSocket WebSocket { get; set; } public string Username { get; set; }} |
我也創建了自定義WebSocket消息:
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class CustomWebSocketMessage{ public string Text { get; set; } public DateTime MessagDateTime { get; set; } public string Username { get; set; } public WSMessageType Type { get; set; }} |
其中Type是您可能擁有的不同類型消息的枚舉。
在Startup類中，您必須注冊以下服務：
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services.AddSingleton<ICustomWebSocketFactory, CustomWebSocketFactory>();services.AddSingleton<ICustomWebSocketMessageHandler, CustomWebSocketMessageHandler>(); |
CustomWebSocketFactory負責收集連接的WebSockets列表：
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public interface ICustomWebSocketFactory{ void Add(CustomWebSocket uws); void Remove(string username); List<CustomWebSocket> All(); List<CustomWebSocket> Others(CustomWebSocket client); CustomWebSocket Client(string username);}public class CustomWebSocketFactory : ICustomWebSocketFactory{ List<CustomWebSocket> List; public CustomWebSocketFactory() { List = new List<CustomWebSocket>(); } public void Add(CustomWebSocket uws) { List.Add(uws); } //when disconnect public void Remove(string username) { List.Remove(Client(username)); } public List<CustomWebSocket> All() { return List; } public List<CustomWebSocket> Others(CustomWebSocket client) { return List.Where(c => c.Username != client.Username).ToList(); } public CustomWebSocket Client(string username) { return List.First(c=>c.Username == username); }} |
CustomWebSocketMessageHandler包含有關消息的邏輯（即在連接時需要發送任何消息以及如何對傳入消息作出反應）
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public interface ICustomWebSocketMessageHandler{ Task SendInitialMessages(CustomWebSocket userWebSocket); Task HandleMessage(WebSocketReceiveResult result, byte[] buffer, CustomWebSocket userWebSocket, ICustomWebSocketFactory wsFactory); Task BroadcastOthers(byte[] buffer, CustomWebSocket userWebSocket, ICustomWebSocketFactory wsFactory); Task BroadcastAll(byte[] buffer, CustomWebSocket userWebSocket, ICustomWebSocketFactory wsFactory);}public class CustomWebSocketMessageHandler : ICustomWebSocketMessageHandler{ public async Task SendInitialMessages(CustomWebSocket userWebSocket) { WebSocket webSocket = userWebSocket.WebSocket; var msg = new CustomWebSocketMessage { MessagDateTime = DateTime.Now, Type = WSMessageType.anyType, Text = anyText, Username = "system" }; string serialisedMessage = JsonConvert.SerializeObject(msg); byte[] bytes = Encoding.ASCII.GetBytes(serialisedMessage); await webSocket.SendAsync(new ArraySegment<byte>(bytes, 0, bytes.Length), WebSocketMessageType.Text, true, CancellationToken.None); } public async Task HandleMessage(WebSocketReceiveResult result, byte[] buffer, CustomWebSocket userWebSocket, ICustomWebSocketFactory wsFactory) { string msg = Encoding.ASCII.GetString(buffer); try { var message = JsonConvert.DeserializeObject<CustomWebSocketMessage>(msg); if (message.Type == WSMessageType.anyType) { await BroadcastOthers(buffer, userWebSocket, wsFactory); } } catch (Exception e) { await userWebSocket.WebSocket.SendAsync(new ArraySegment<byte>(buffer, 0, result.Count), result.MessageType, result.EndOfMessage, CancellationToken.None); } } public async Task BroadcastOthers(byte[] buffer, CustomWebSocket userWebSocket, ICustomWebSocketFactory wsFactory) { var others = wsFactory.Others(userWebSocket); foreach (var uws in others) { await uws.WebSocket.SendAsync(new ArraySegment<byte>(buffer, 0, buffer.Length), WebSocketMessageType.Text, true, CancellationToken.None); } } public async Task BroadcastAll(byte[] buffer, CustomWebSocket userWebSocket, ICustomWebSocketFactory wsFactory) { var all = wsFactory.All(); foreach (var uws in all) { await uws.WebSocket.SendAsync(new ArraySegment<byte>(buffer, 0, buffer.Length), WebSocketMessageType.Text, true, CancellationToken.None); } }} |
最后，在Configure方法的Startup類中添加以下內容：
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var webSocketOptions = new WebSocketOptions(){ KeepAliveInterval = TimeSpan.FromSeconds(120), ReceiveBufferSize = 4 * 1024};app.UseWebSockets(webSocketOptions);app.UseCustomWebSocketManager(); |
通過這種方式，Starup類保持干凈，管理WebSockets的邏輯可以擴展，使您可以根據自己的喜好靈活地組織它。
總結
以上就是這篇文章的全部內容了，希望本文的內容對大家的學習或者工作具有一定的參考學習價值，如果有疑問大家可以留言交流，謝謝大家對服務器之家的支持。
原文鏈接：http://www.nopapp.com/Blog/Article/middleware-websocket-aspnetcore
