Asp.net core 信号器-向特定用户发送消息

我正在学习

SignalR

Microsoft教程

一切正常，但是，我想尝试更改

ChatHub#SendMessage

中的代码，以便向特定用户发送消息

所以我修改代码如下：

public class ChatHub : Hub
{
    public async Task SendMessage(string user, string message)
    {
        //await Clients.All.SendAsync("ReceiveMessage", user, message);

        await Clients.User(user).SendAsync("ReceiveMessage", message);
    }
}

public async Task SendMessage(string user, string message)
{
    //await Clients.All.SendAsync("ReceiveMessage", user, message);

    await Clients.User(Context.UserIdentifier).SendAsync("ReceiveMessage", message);
}

public async Task SendMessage(string user, string message)
{
    //await Clients.All.SendAsync("ReceiveMessage", user, message);

    await Clients.User(user).SendAsync("ReceiveMessage", user, message); // <-- add user parameter
}

但是，用户从未收到消息。只有在使用

Clients.All.SendAsync

时才会发送消息（这是上面注释掉的行）

我还做了更多的研究，发现也许我需要实现一个定制的用户提供者。所以我实施了一个：

public class CustomUserIdProvider : IUserIdProvider
{
    public string GetUserId(HubConnectionContext connection)
    {
        return "user1";
    }
}

然后在

Startup.cs

中，我注册了此提供商：

public void ConfigureServices(IServiceCollection services)
{
    services.AddRazorPages();
    services.AddSingleton<IUserIdProvider, CustomUserIdProvider>();
    services.AddSignalR();
}

但它似乎仍然没有发出信息

---

我做错了什么？

我这样做的方式是，当用户登录时，我将他们添加到信号器组，该组是用户的ID或名称。这样一来，它就是一个唯一的用户组。然后我把信息发送给那群人。只有该用户才会收到该消息，因为他们是该组中唯一的用户

客户端代码：

// Optional: authenticate with a server, get a token... or send username/password in following request

_hub = new HubConnectionBuilder()
    .WithUrl(_envSettings.CreatePlayerServiceHubPath(), x =>
    {
        x.Headers.Add("x-lcc-version", AppEnvironment.Application.Version);
        x.Headers.Add("x-lcc-username", username);
        x.Headers.Add("x-lcc-authorization", token);
    })
    .AddNewtonsoftJsonProtocol()
    .Build();

_hub.Closed += OnSignalRDisconnectedFromServerAsync;
SetupRPCs();
await _hub.StartAsync().ConfigureAwait(false);

public override async Task OnConnectedAsync()
{
    var userName = Context.GetHttpContext().Request.Headers["x-lcc-username"];
    var token = Context.GetHttpContext().Request.Headers["x-lcc-authorization"];
    
    // Optional: validate authorization
    
    await Groups.AddToGroupAsync(Context.ConnectionId, userName);
    
    // Then when you want to send a message to the user:
    await Clients.Group(userName).SendAsync("hello", "world");
}

服务器端代码：

// Optional: authenticate with a server, get a token... or send username/password in following request

_hub = new HubConnectionBuilder()
    .WithUrl(_envSettings.CreatePlayerServiceHubPath(), x =>
    {
        x.Headers.Add("x-lcc-version", AppEnvironment.Application.Version);
        x.Headers.Add("x-lcc-username", username);
        x.Headers.Add("x-lcc-authorization", token);
    })
    .AddNewtonsoftJsonProtocol()
    .Build();

_hub.Closed += OnSignalRDisconnectedFromServerAsync;
SetupRPCs();
await _hub.StartAsync().ConfigureAwait(false);

public override async Task OnConnectedAsync()
{
    var userName = Context.GetHttpContext().Request.Headers["x-lcc-username"];
    var token = Context.GetHttpContext().Request.Headers["x-lcc-authorization"];
    
    // Optional: validate authorization
    
    await Groups.AddToGroupAsync(Context.ConnectionId, userName);
    
    // Then when you want to send a message to the user:
    await Clients.Group(userName).SendAsync("hello", "world");
}

有趣的是，当用户断开连接时，

组自动消失。您不必维护正在创建的组

我知道这可能不是你想要的100%，但这是一个如何处理其他场景中类似情况的想法。
我这样做的方式是当用户登录时，我将他们添加到信号器组中，该组是用户的ID或名称。这样一来，它就是一个唯一的用户组。然后我把信息发送给那群人。只有该用户才会收到该消息，因为他们是该组中唯一的用户

客户端代码：

// Optional: authenticate with a server, get a token... or send username/password in following request

_hub = new HubConnectionBuilder()
    .WithUrl(_envSettings.CreatePlayerServiceHubPath(), x =>
    {
        x.Headers.Add("x-lcc-version", AppEnvironment.Application.Version);
        x.Headers.Add("x-lcc-username", username);
        x.Headers.Add("x-lcc-authorization", token);
    })
    .AddNewtonsoftJsonProtocol()
    .Build();

_hub.Closed += OnSignalRDisconnectedFromServerAsync;
SetupRPCs();
await _hub.StartAsync().ConfigureAwait(false);

public override async Task OnConnectedAsync()
{
    var userName = Context.GetHttpContext().Request.Headers["x-lcc-username"];
    var token = Context.GetHttpContext().Request.Headers["x-lcc-authorization"];
    
    // Optional: validate authorization
    
    await Groups.AddToGroupAsync(Context.ConnectionId, userName);
    
    // Then when you want to send a message to the user:
    await Clients.Group(userName).SendAsync("hello", "world");
}

服务器端代码：

// Optional: authenticate with a server, get a token... or send username/password in following request

_hub = new HubConnectionBuilder()
    .WithUrl(_envSettings.CreatePlayerServiceHubPath(), x =>
    {
        x.Headers.Add("x-lcc-version", AppEnvironment.Application.Version);
        x.Headers.Add("x-lcc-username", username);
        x.Headers.Add("x-lcc-authorization", token);
    })
    .AddNewtonsoftJsonProtocol()
    .Build();

_hub.Closed += OnSignalRDisconnectedFromServerAsync;
SetupRPCs();
await _hub.StartAsync().ConfigureAwait(false);

public override async Task OnConnectedAsync()
{
    var userName = Context.GetHttpContext().Request.Headers["x-lcc-username"];
    var token = Context.GetHttpContext().Request.Headers["x-lcc-authorization"];
    
    // Optional: validate authorization
    
    await Groups.AddToGroupAsync(Context.ConnectionId, userName);
    
    // Then when you want to send a message to the user:
    await Clients.Group(userName).SendAsync("hello", "world");
}

有趣的是，当用户断开连接时，
组自动消失。您不必维护正在创建的组

我知道这可能不是你想要的100%，但这是一个如何处理其他场景中类似情况的想法。
我发现了这个问题。我在
Clients.user（user.SendAsync
调用中省略了user参数

所以它应该是这样的：

public class ChatHub : Hub
{
    public async Task SendMessage(string user, string message)
    {
        //await Clients.All.SendAsync("ReceiveMessage", user, message);

        await Clients.User(user).SendAsync("ReceiveMessage", message);
    }
}

public async Task SendMessage(string user, string message)
{
    //await Clients.All.SendAsync("ReceiveMessage", user, message);

    await Clients.User(Context.UserIdentifier).SendAsync("ReceiveMessage", message);
}

public async Task SendMessage(string user, string message)
{
    //await Clients.All.SendAsync("ReceiveMessage", user, message);

    await Clients.User(user).SendAsync("ReceiveMessage", user, message); // <-- add user parameter
}

公共异步任务发送消息（字符串用户，字符串消息）
{
//等待Clients.All.SendAsync（“ReceiveMessage”，user，message）；
wait Clients.User（User）.SendAsync（“ReceiveMessage”，User，message）；//我发现了问题。我在
Clients.User（User）.SendAsync调用中省略了用户参数

所以它应该是这样的：

public class ChatHub : Hub
{
    public async Task SendMessage(string user, string message)
    {
        //await Clients.All.SendAsync("ReceiveMessage", user, message);

        await Clients.User(user).SendAsync("ReceiveMessage", message);
    }
}

public async Task SendMessage(string user, string message)
{
    //await Clients.All.SendAsync("ReceiveMessage", user, message);

    await Clients.User(Context.UserIdentifier).SendAsync("ReceiveMessage", message);
}

public async Task SendMessage(string user, string message)
{
    //await Clients.All.SendAsync("ReceiveMessage", user, message);

    await Clients.User(user).SendAsync("ReceiveMessage", user, message); // <-- add user parameter
}

公共异步任务发送消息（字符串用户，字符串消息）
{
//等待Clients.All.SendAsync（“ReceiveMessage”，user，message）；
等待Clients.User（User）.SendAsync（“ReceiveMessage”，User，message）；//你看过了吗？@Andy-谢谢你的链接，我确实看过了。但是，不幸的是，这不是dotnet core的。啊，糟糕……我讨厌这样。但其中一些可能会转移。我会补充一个关于我如何处理基于组的用户的答案。也许以后会有用。你看过了吗？@Andy-谢谢你的链接，我看过了看看这个。然而，不幸的是，它不是为dotnet core设计的。啊，糟糕。我讨厌它。但其中一些可能会转移。我将添加一个关于我如何处理基于组的用户的答案。也许这在以后可能会有用。非常感谢你提供的信息，我可能会在某个时候使用这个想法。非常感谢你提供的信息，我可能最终会使用这个想法有一点。