Asp.net Core中如何使用中间件来管理websocket

在这种情况下，WebSockets请求在URL中始终包含“/ ws”。查询字符串包含用于将WebSocket与登录用户相关联的用户名的参数u。

CustomWebSocket是一个包含WebSocket和用户名的类：

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

我也创建了自定义WebSocket消息:

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是您可能拥有的不同类型消息的枚举。

在Startup类中，您必须注册以下服务：

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

CustomWebSocketFactory负责收集连接的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包含有关消息的逻辑（即在连接时需要发送任何消息以及如何对传入消息作出反应）

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);
  }
 }
}								 
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