通过Microsoft.Extensions.Hosting.BackgroundService抽象类开启后台任务。

/// Copyright(c) .NET Foundation.Licensed under the Apache License, Version 2.0.
    /// <summary>
    /// Base class for implementing a long running <see cref="IHostedService"/>.
    /// </summary>
    public abstract class BackgroundService : IHostedService, IDisposable
    {
        protected readonly IServiceScopeFactory _scopeFactory;
        private Task _executingTask;
        private readonly CancellationTokenSource _stoppingCts =
                                                       new CancellationTokenSource();

        public BackgroundService(IServiceScopeFactory scopeFactory) {
            _scopeFactory = scopeFactory;
        }

        protected abstract Task ExecuteAsync(CancellationToken stoppingToken);

        public virtual Task StartAsync(CancellationToken cancellationToken)
        {
            // Store the task we're executing
            _executingTask = ExecuteAsync(_stoppingCts.Token);

            // If the task is completed then return it,
            // this will bubble cancellation and failure to the caller
            if (_executingTask.IsCompleted)
            {
                return _executingTask;
            }

            // Otherwise it's running
            return Task.CompletedTask;
        }

        public virtual async Task StopAsync(CancellationToken cancellationToken)
        {
            // Stop called without start
            if (_executingTask == null)
            {
                return;
            }

            try
            {
                // Signal cancellation to the executing method
                _stoppingCts.Cancel();
            }
            finally
            {
                // Wait until the task completes or the stop token triggers
                await Task.WhenAny(_executingTask, Task.Delay(Timeout.Infinite,
                                                              cancellationToken));
            }
        }

        public virtual void Dispose()
        {
            _stoppingCts.Cancel();
        }
    }

实现：

/// <summary>
/// 实现 BackManagerService 类继承 BackgroundService 抽象类
/// </summary>
public class BackManagerService : BackgroundService
{
    protected override async Task ExecuteAsync(CancellationToken stoppingToken)
    {
        while (!stoppingToken.IsCancellationRequested)
        {
	        Foo();//需要运行的方法
            await Task.Delay(TimeSpan.FromSeconds(30), stoppingToken);
        }
    }
}

然后打开 Startup.cs 在 ConfigureServices 方法注入

public void ConfigureServices(IServiceCollection services)
{
    services.AddSingleton<IHostedService, BackManagerService>();

    services.AddMvc().SetCompatibilityVersion(CompatibilityVersion.Version_2_1);
}