C#中間件如何管理WebSocket會話池

在C#中，要管理WebSocket會話池，你需要創建一個類來存儲和處理所有活動的WebSocket連接。以下是一個簡單的示例，展示了如何使用中間件來管理WebSocket會話池：

1. 首先，安裝Microsoft.AspNetCore.WebSockets包：

dotnet add package Microsoft.AspNetCore.WebSockets

2. 創建一個WebSocketSession類，用于存儲WebSocket連接信息：

public class WebSocketSession
{
    public string Id { get; set; }
    public WebSocket WebSocket { get; set; }
}

3. 創建一個WebSocketSessionManager類，用于管理WebSocket會話池：

public class WebSocketSessionManager
{
    private ConcurrentDictionary<string, WebSocketSession> _sessions = new ConcurrentDictionary<string, WebSocketSession>();

    public void AddSession(WebSocketSession session)
    {
        _sessions.TryAdd(session.Id, session);
    }

    public void RemoveSession(string id)
    {
        _sessions.TryRemove(id, out _);
    }

    public WebSocketSession GetSessionById(string id)
    {
        _sessions.TryGetValue(id, out var session);
        return session;
    }

    public List<WebSocketSession> GetAllSessions()
    {
        return _sessions.Values.ToList();
    }
}

4. 創建一個中間件來處理WebSocket請求：

public class WebSocketMiddleware
{
    private readonly RequestDelegate _next;
    private readonly WebSocketSessionManager _sessionManager;

    public WebSocketMiddleware(RequestDelegate next, WebSocketSessionManager sessionManager)
    {
        _next = next;
        _sessionManager = sessionManager;
    }

    public async Task InvokeAsync(HttpContext context)
    {
        if (context.WebSockets.IsWebSocketRequest)
        {
            var webSocket = await context.WebSockets.AcceptWebSocketAsync();
            var session = new WebSocketSession
            {
                Id = Guid.NewGuid().ToString(),
                WebSocket = webSocket
            };

            _sessionManager.AddSession(session);

            try
            {
                await HandleWebSocketSession(session);
            }
            finally
            {
                _sessionManager.RemoveSession(session.Id);
            }
        }
        else
        {
            await _next(context);
        }
    }

    private async Task HandleWebSocketSession(WebSocketSession session)
    {
        var buffer = new byte[1024 * 4];
        var result = await session.WebSocket.ReceiveAsync(new ArraySegment<byte>(buffer), CancellationToken.None);

        while (!result.CloseStatus.HasValue)
        {
            // Process received data
            // ...

            // Send data to client
            // ...

            result = await session.WebSocket.ReceiveAsync(new ArraySegment<byte>(buffer), CancellationToken.None);
        }

        await session.WebSocket.CloseAsync(result.CloseStatus.Value, result.CloseStatusDescription, CancellationToken.None);
    }
}

5. 在Startup類中注冊中間件和WebSocketSessionManager：

public class Startup
{
    public void ConfigureServices(IServiceCollection services)
    {
        services.AddSingleton<WebSocketSessionManager>();
    }

    public void Configure(IApplicationBuilder app, IWebHostEnvironment env)
    {
        app.UseWebSockets();
        app.UseMiddleware<WebSocketMiddleware>();

        // Other middlewares
        // ...
    }
}

現在，你已經創建了一個可以管理WebSocket會話池的中間件。你可以通過WebSocketSessionManager類的實例來訪問和操作所有活動的WebSocket連接。