ASP.NET Core SignalR 从任何地方访问 Hub 方法

Question

如果在这个问题上花了很多时间，我发现了很多不同的策略，但没有一个对我有用。（此代码只是概念的证明。）

我使用 Asp.net core 2.1（在 .Net Framwork 4.7.2 上）进行了以下设置：

我制作了一个信号集线器，它有一种发送数字的方法：

using System.Threading.Tasks;
using Microsoft.AspNetCore.SignalR;


namespace TestRandomNumberSignalR
{
    public class TestHub : Hub
    {
        public async Task SendRandomNumber(int number)
        {
            await Clients.All.SendAsync("ReceiveRandomBumber", number);
        }
    }
}

我还创建了一个每 3 秒更新一个随机数并将其添加为单例的类：

using Microsoft.AspNetCore.Builder;
using Microsoft.AspNetCore.Hosting;
using Microsoft.AspNetCore.Mvc;
using Microsoft.Extensions.Configuration;
using Microsoft.Extensions.DependencyInjection;

namespace TestRandomNumberSignalR
{
    public class Startup
    {
        public Startup(IConfiguration configuration)
        {
            Configuration = configuration;
        }

        public IConfiguration Configuration { get; }

        // This method gets called by the runtime. Use this method to add services to the container.
        public void ConfigureServices(IServiceCollection services)
        {
            services.AddSingleton(new UpdateRandomNumber());
            services.AddSignalR();
            services.AddMvc().SetCompatibilityVersion(CompatibilityVersion.Version_2_1);
        }

        // This method gets called by the runtime. Use this method to configure the HTTP request pipeline.
        public void Configure(IApplicationBuilder app, IHostingEnvironment env)
        {
            if (env.IsDevelopment())
            {
                app.UseDeveloperExceptionPage();
            }

            app.UseMvc();
            app.UseSignalR(routes =>
            {
                routes.MapHub<TestHub>("/testHub");
            });
        }
    }
}

这是随机数类：

using System;
using System.Threading;
using System.Threading.Tasks;

namespace TestRandomNumberSignalR
{
    public class UpdateRandomNumber
    {
        private bool _continue = true;

        public UpdateRandomNumber()
        {
            var task = new Task(() => RandomNumberLoop(),
                                TaskCreationOptions.LongRunning);
            task.Start();
        }

        private void RandomNumberLoop()
        {
            Random r = new Random();

            while (_continue)
            {
                Thread.Sleep(3000);
                int number = r.Next(0, 100);
                Console.WriteLine("The random number is now " + number);

                // Send new random number to connected subscribers here
                // Something like TestHub.SendRandomNumber(number);

            }
        }

        public void Stop()
        {
            _continue = false;
        }
    }
}

现在从这个类（正如我在评论中所写）我想使用 SignalR 发送新的随机数。只有如何在那里获取集线器上下文？

此外，我希望能够从控制器内访问类上的 Stop() 方法，我该如何访问？

我现在这是一个很好讨论的主题，但我仍然无法在任何地方找到可行的解决方案。希望您能够帮助我。

编辑

问题 1

虽然随机循环现在开始（非常感谢rasarasha），但仍然存在一些问题。我现在无法将正确的 UpdateRandomNumber 注入控制器。假设我希望能够停止调用 UpdateRandomNumber.Stop() 方法的循环，如何将 UpdateRandomNumber 单例注入控制器。我尝试创建一个界面：

public interface IUpdateRandomNumber
{
    void Stop();
}

更改 RandomNumber 方法以实现此目的：

public class UpdateRandomNumber : IUpdateRandomNumber
{
    private bool _continue = true;

    private IHubContext<TestHub> testHub;

    public UpdateRandomNumber(IHubContext<TestHub> testHub)        
    {
        this.testHub = testHub;

        var task = new Task(() => RandomNumberLoop(),
                            TaskCreationOptions.LongRunning);
        task.Start();
    }

    private void RandomNumberLoop()
    {
        Random r = new Random();

        while (_continue)
        {

            Thread.Sleep(3000);
            int number = r.Next(0, 100);
            Console.WriteLine("The random number is now " + number);

            // Send new random number to connected subscribers here
            // Something like TestHub.SendRandomNumber(number);

        }
    }

    public void Stop()
    {
        _continue = false;
    }
}

并更改添加单例方法，以便使用该接口：

        services.AddSingleton<IUpdateRandomNumber>(provider =>
        {
            var hubContext = provider.GetService<IHubContext<TestHub>>();
            var updateRandomNumber = new UpdateRandomNumber(hubContext);
            return updateRandomNumber;
        });

我现在可以使用停止随机数循环的方法创建一个控制器：

[Route("api/[controller]")]
[ApiController]
public class RandomController : ControllerBase
{
    private readonly IUpdateRandomNumber _updateRandomNumber;

    public RandomController(IUpdateRandomNumber updateRandomNumber)
    {
        _updateRandomNumber = updateRandomNumber;
    }

    // POST api/random
    [HttpPost]
    public void Post()
    {
        _updateRandomNumber.Stop();
    }

但是，此实现将阻止循环再次启动。那么如何从控制器访问 rondomnumber 单例呢？

问题2

从我的 UpdateRandomNumber 类，我现在可以调用：

testHub.Clients.All.SendAsync("ReceiveRandomBumber", number);

但是为什么我要在我的 testhub 中创建该方法：

    public async Task SendRandomNumber(int number)
    {
        await Clients.All.SendAsync("ReceiveRandomBumber", number);
    }

在集线器中创建方法并直接调用它们会更方便。这能做到吗？

Answer 1

您可以使用构造函数注入将 TestHub 注入控制器。因为它已经在 DI 容器中注册了。

public class UpdateRandomNumber
{
    private bool _continue = true;
    private IHubContext<TestHub> testHub;
    private Task randomNumberTask;
    public UpdateRandomNumber(IHubContext<TestHub> testHub)
    {
        this.testHub=testHub;
        randomNumberTask = new Task(() => RandomNumberLoop(),
            TaskCreationOptions.LongRunning);
        randomNumberTask.Start();
    }
    private async void RandomNumberLoop()
    {
        Random r = new Random();

        while (_continue)
        {
            Thread.Sleep(3000);
            int number = r.Next(0, 100);
            Console.WriteLine("The random number is now " + number);

            // Send new random number to connected subscribers here
             await testHub.Clients.All.SendAsync($"ReceiveRandomNumber", number);

        }
    }

    public void Stop()
    {
        _continue = false;
    }
}
public class Startup
{
    public Startup(IConfiguration configuration)
    {
        Configuration = configuration;
    }

    public IConfiguration Configuration { get; }

    // This method gets called by the runtime. Use this method to add services to the container.
    public void ConfigureServices(IServiceCollection services)
    {

        services.AddSignalR();
        services.AddMvc().SetCompatibilityVersion(CompatibilityVersion.Version_2_2);
        services.AddSingleton(provider =>
        {
            var hubContext = provider.GetService<IHubContext<TestHub>>();
            var updateRandomNumber = new UpdateRandomNumber(hubContext);
            return updateRandomNumber;
        });

    }

    // This method gets called by the runtime. Use this method to configure the HTTP request pipeline.
    public void Configure(IApplicationBuilder app, IHostingEnvironment env)
    {
        var updateRandonNumber = app.ApplicationServices.GetService<UpdateRandomNumber>();
        if (env.IsDevelopment())
        {
            app.UseDeveloperExceptionPage();
        }

        app.UseMvc();
        app.UseSignalR(routes =>
        {
            routes.MapHub<TestHub>("/testHub");
        });
    }
}