问题描述

我发现的构建控制台应用程序的所有示例都创建了一个实现IHostedService或扩展Backround Service的类。然后通过AddHostedService将该类添加到服务容器，并通过StartAsync或ExecuteAsync启动应用程序的工作。然而，似乎在所有这些示例中，它们都实现了一个在循环中运行的后台服务或某个其他应用程序，或者等待请求，直到它被操作系统关闭或接收到某种终止请求。如果我只想要一个启动、正常工作然后退出的应用程序，该怎么办？例如：

Program.cs：

namespace MyApp
{
    using System;
    using System.Threading.Tasks;
    using Microsoft.Extensions.DependencyInjection;
    using Microsoft.Extensions.Hosting;
    using Microsoft.Extensions.Logging;

    public static class Program
    {
        public static async Task Main(string[] args)
        {
            await CreateHostBuilder(args).RunConsoleAsync();
        }

        private static IHostBuilder CreateHostBuilder(string[] args) =>
            Host.CreateDefaultBuilder(args)
                .UseConsoleLifetime()
                .ConfigureLogging(builder => builder.SetMinimumLevel(LogLevel.Warning))
                .ConfigureServices((hostContext, services) =>
                {
                    services.Configure<MyServiceOptions>(hostContext.Configuration);
                    services.AddHostedService<MyService>();
                    services.AddSingleton(Console.Out);
                });
    }
}

MyServiceOptions.cs：

namespace MyApp
{
    public class MyServiceOptions
    {
        public int OpCode { get; set; }
        public int Operand { get; set; }
    }
}

MyService.cs：

namespace MyApp
{
    using System.IO;
    using System.Threading;
    using System.Threading.Tasks;
    using Microsoft.Extensions.Hosting;
    using Microsoft.Extensions.Options;

    public class MyService : IHostedService
    {
        private readonly MyServiceOptions _options;
        private readonly TextWriter _outputWriter;

        public MyService(TextWriter outputWriter, IOptions<MyServiceOptions> options)
        {
            _options = options.Value;
            _outputWriter = outputWriter;
        }

        public async Task StartAsync(CancellationToken cancellationToken)
        {
            _outputWriter.WriteLine("Starting work");

            DoOperation(_options.OpCode, _options.Operand);

            _outputWriter.WriteLine("Work complete");
        }

        public async Task StopAsync(CancellationToken cancellationToken)
        {
            _outputWriter.WriteLine("StopAsync");
        }

        protected void DoOperation(int opCode, int operand)
        {
            _outputWriter.WriteLine("Doing {0} to {1}...", opCode, operand);

            // Do work that might take awhile
        }
    }
}

此代码编译和运行良好，生成以下输出：

Starting work
Doing 1 to 2...
Work complete

推荐答案

代替托管服务，我建议使用以下服务；

using (var host = CreateHostBuilder(args).Build())
{
    await host.StartAsync();
    var lifetime = host.Services.GetRequiredService<IHostApplicationLifetime>();

    // do work here / get your work service ...

    lifetime.StopApplication();
    await host.WaitForShutdownAsync();
}

这篇关于创建没有后台服务的.NET核心控制台应用程序的正确方法的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持编程学习网！