.NET Core 中基于 IHostedService 实现后台定时任务

.NET Core 2.0 引入了 IHostedService ，基于它可以很方便地执行后台任务，.NET Core 2.1 则锦上添花地提供了 IHostedService 的默认实现基类 BackgroundService ，在这篇随笔中分别用 Web 与 Console 程序体验一下。

首先继承 BackgroundService 实现一个 TimedBackgroundService

public class TimedBackgroundService : BackgroundService{ ???private readonly ILogger _logger; ???private Timer _timer; ???public TimedBackgroundService(ILogger<TimedBackgroundService> logger) ???{ ???????_logger = logger; ???} ???protected override Task ExecuteAsync(CancellationToken stoppingToken) ???{ ???????_timer = new Timer(DoWork, null, TimeSpan.Zero, TimeSpan.FromSeconds(5)); ???????return Task.CompletedTask; ???} ???private void DoWork(object state) ???{ ???????_logger.LogInformation($"Hello World! - {DateTime.Now}"); ???} ???public override void Dispose() ???{ ???????base.Dispose(); ???????_timer?.Dispose(); ???}}

在 ASP.NET Core Web 程序中执行这个后台定时任务只需在 Startup 的 ConfigureServices 注册 TimedBackgroundService 即可：

public void ConfigureServices(IServiceCollection services){ ???services.AddHostedService<TimedBackgroundService>();}

然后只要站点启动，就会定时输出日志：

Now listening on: http://localhost:5000Application started. Press Ctrl+C to shut down.info: BackgroundServiceSample.Services.TimedBackgroundService[0] ?????Hello World! - 9/14/2018 17:48:02info: BackgroundServiceSample.Services.TimedBackgroundService[0] ?????Hello World! - 9/14/2018 17:48:07info: BackgroundServiceSample.Services.TimedBackgroundService[0] ?????Hello World! - 9/14/2018 17:48:12

接下来在控制台程序中体验一下。
基于 Generic Host 实现如下的控制台程序，也是执行在 ConfigureServices 中注册一下 TimedBackgroundService 。

class Program{ ???public static async Task Main(string[] args) ???{ ???????var builder = new HostBuilder() ???????????.ConfigureLogging(logging => ???????????{ ???????????????logging.AddConsole(); ???????????}) ???????????.ConfigureServices((hostContext, services) => ???????????{ ???????????????services.AddHostedService<TimedBackgroundService>(); ???????????}); ???????await builder.RunConsoleAsync(); ???}}

dotnet run 运行程序后 TimedBackgroundService 定时输出了日志：

info: BackgroundServiceSample.Services.TimedBackgroundService[0] ?????Hello World! - 9/14/2018 17:59:37info: BackgroundServiceSample.Services.TimedBackgroundService[0] ?????Hello World! - 9/14/2018 17:59:42info: BackgroundServiceSample.Services.TimedBackgroundService[0] ?????Hello World! - 9/14/2018 17:59:47

体验完成。

.NET Core 中基于 IHostedService 实现后台定时任务

原文地址：https://www.cnblogs.com/dudu/p/9647619.html