這里去掉“使用控制器”來構(gòu)建最小API服務(wù)。

最后點擊【創(chuàng)建】。

2、在項目中安裝 SignalR 包

使用 NuGet 包管理器 UI 通過搜索“SignalR”，找到“Microsoft.AspNetCore.SignalR”安裝

當(dāng)然，也可以通過NuGet 包管理器控制臺來通過命令安裝：

Install-Package Microsoft.AspNetCore.SignalR

3、在啟動文件Program.cs中添加?SignalR 服務(wù)

builder.Services.AddSignalR();

4、創(chuàng)建Hub類?SignalRHub.cs

using Microsoft.AspNetCore.SignalR;



namespace SignalRApi

{

    public class SignalRHub : Hub

    {

        /// <summary>

        /// 發(fā)布學(xué)生成績

        /// </summary>

        /// <param name="name">學(xué)生姓名</param>

        /// <param name="score">得分</param>

        /// <param name="msg">備注</param>

        /// <returns></returns>

        public async Task SendMessage(string name, int score, string msg)

        {

            await Clients.All.SendAsync("ReceiveScore", name, score, msg);

        }

        public override async Task OnConnectedAsync()

        {

            string connectionId = Context.ConnectionId;

            await base.OnConnectedAsync();

        }

    }

}

5、創(chuàng)建后臺服務(wù)持續(xù)推送消息類 WorkerService.cs 

具體業(yè)務(wù)邏輯代碼：

using Microsoft.AspNetCore.SignalR;



namespace SignalRApi

{

    public class WorkerService : BackgroundService

    {

        private readonly IHubContext<SignalRHub> _signalRHub;



        public WorkerService(IHubContext<SignalRHub> signalRHub)

        {

            _signalRHub = signalRHub;

        }



        protected override async Task ExecuteAsync(CancellationToken stoppingToken)

        {

            while (!stoppingToken.IsCancellationRequested)

            {

                try

                {

                    Console.WriteLine($"{DateTime.Now}：服務(wù)已啟動");

                    Random rnd = new Random();

                    int score = rnd.Next(60, 100);

                    string[] students = { "段譽", "蕭峰", "虛竹", "阿朱", "阿紫", "王語嫣", "木婉清", "鐘靈", "阿碧", "慕容復(fù)", "段正淳", "鳩摩智" };

                    var name = students[rnd.Next(0, students.Length)];

                    await _signalRHub.Clients.All.SendAsync("ReceiveScore", name, score, $"{name}的成績是{score}");

                    Console.WriteLine($"{DateTime.Now}：發(fā)布成績：{name}獲取{score}分");

                    await Task.Delay(4000, stoppingToken);

                }

                catch (Exception ex)

                {

                    Console.WriteLine($"服務(wù)異常：{ex.Message}");

                }

            }

        }

    }

}

6、最后，需要在Program.cs中映射 SignalRHub 以及添加后臺服務(wù)

builder.Services.AddHostedService<WorkerService>();



app.MapHub<SignalRHub>("/hubs/score");

啟動項目，查看效果：

SignalR服務(wù)端搭建完畢，接下來，實現(xiàn)SignalR的客戶端，用控制臺程序?qū)崿F(xiàn)。

創(chuàng)建 SignalR 客戶端

1、創(chuàng)建控制臺應(yīng)用程序

同樣的方法安裝SignalR客戶端包【Microsoft.AspNetCore.SignalR.Client】，

在Program.cs中添加代碼：

using Microsoft.AspNetCore.SignalR.Client;

//here is SignalR Sender URL  

string hubUrl = "http://localhost:5000/hubs/score";

var hubConnection = new HubConnectionBuilder().WithUrl(hubUrl).Build();



// Register a handler for messages from the SignalR hub  

// "ReceiveStockPrice" is the topic to which SignalR sending the singnals  

hubConnection.On<string, int, string>("ReceiveScore", (name, score, msg) =>

{

    Console.WriteLine($"接收消息--> 學(xué)生：{name} 成績：{score} 備注：{msg}");

});



try

{

    // Start the connection  

    hubConnection.StartAsync().Wait();

    Console.WriteLine("SignalR 已連接到服務(wù)器");

}

catch (Exception ex)

{

    Console.WriteLine($"SignalR 連接服務(wù)異常：{ex.Message}");

    throw;

}

CancellationTokenSource cancellationTokenSource = new CancellationTokenSource();

var cancellationToken = cancellationTokenSource.Token;

Console.CancelKeyPress += (sender, a) =>

{

    a.Cancel = true;

    Console.WriteLine("SignalR 停止連接");

    cancellationTokenSource.Cancel();

};

try

{

    await Task.Delay(Timeout.Infinite, cancellationToken);

}

catch (TaskCanceledException)

{

}

await hubConnection.StopAsync();



Console.WriteLine("SignalR 連接已關(guān)閉");

啟動項目，查看效果：

本文章轉(zhuǎn)載微信公眾號@武穆逸仙