在Asp.net Core中使用中介軟體來管理websocket

介紹

ASP.NET Core SignalR是一個有用的庫，可以簡化Web應用程式中即時通訊的管理。但是，我寧願使用WebSockets，因為我想要更靈活，並且與任何WebSocket用戶端相容。

在Microsoft的文檔中，我找到了一個很好的WebSockets工作樣本。它仍然是管理串連，以便能夠從一個串連向其他串連廣播訊息，這是SignalR開箱即用的功能。期望這個邏輯非常複雜，我想從Startup類中刪除它。

背景

要閱讀ASP.NET Core中的WebSockets支援，可以在此處查看。如果您想瞭解中介軟體以及如何在ASP.NET Core中編寫它，請閱讀此連結。

代碼使用

首先，你必須添加 Microsoft.AspNetCore.WebSockets 包到你的項目。

現在，您可以建立一個擴充方法和類來管理WebSockets：

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”。查詢字串包含用於將WebSocket與登入使用者相關聯的使用者名稱的參數u。

CustomWebSocket是一個包含WebSocket和使用者名稱的類：

public class CustomWebSocket{   public WebSocket WebSocket { get; set; }   public string Username { get; set; }}

我也建立了自訂WebSocket訊息:

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訊息的枚舉。

在Startup類中，您必須註冊以下服務：

services.AddSingleton<ICustomWebSocketFactory, CustomWebSocketFactory>();services.AddSingleton<ICustomWebSocketMessageHandler, CustomWebSocketMessageHandler>();

CustomWebSocketFactory負責收集串連的WebSockets列表：

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包含有關訊息的邏輯（即在串連時需要發送任何訊息以及如何對傳入訊息作出反應）

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);      }   }}

最後，在Configure方法的Startup類中添加以下內容：

var webSocketOptions = new WebSocketOptions(){    KeepAliveInterval = TimeSpan.FromSeconds(120),    ReceiveBufferSize = 4 * 1024};app.UseWebSockets(webSocketOptions);app.UseCustomWebSocketManager();

通過這種方式，Starup類保持乾淨，管理WebSockets的邏輯可以擴充，使您可以根據自己的喜好靈活地組織它。喜歡這篇文章就吧。在Asp.net Core中使用中介軟體來管理websocket