如何传递BackgroundService的参数? [英] How to pass parameters for BackgroundService?

问题描述

我了解了ASP.net core 2.2，并找到了有关通用主机的参考.

I read about ASP.net core 2.2 and I found reference about generic host.

在以下示例中，我尝试使用backgroundService创建控制台应用程序: https://github.com/aspnet/AspNetCore.Docs/tree/master/aspnetcore/fundamentals/host/generic-host/samples/

I tried to create console app with backgroundService under example: https://github.com/aspnet/AspNetCore.Docs/tree/master/aspnetcore/fundamentals/host/generic-host/samples/

var param = Console.ReadLine();

var host = new HostBuilder().ConfigureServices((hostContext, services) =>
{
   services.AddHostedService<MyCustomSerivce>();
}

问题在于如何从命令行(在我的情况下为"param")中传递参数，该参数将在特定的后台服务中指定内部逻辑.

The problem is how can be passed argument from command line (in my case 'param'), that will specified internal logic in particular background service.

推荐答案

要解析服务，您需要将参数注册到服务集合中.

For resolving service, you need to register the parameters into service collection.

1. 用于存储参数的服务

1. Service for storing the parameter

public class CommandLineArgs
{
    public string Args { get; set; }
}

注册参数

Register the parameter

public class Program
{
    public static async Task Main(string[] args)
    {
        var param = Console.ReadLine();

        var host = new HostBuilder()
            .ConfigureHostConfiguration(configHost =>
            {
                configHost.SetBasePath(Directory.GetCurrentDirectory());
                configHost.AddJsonFile("hostsettings.json", optional: true);
                configHost.AddEnvironmentVariables(prefix: "PREFIX_");
                configHost.AddCommandLine(args);
            })
            .ConfigureAppConfiguration((hostContext, configApp) =>
            {
                configApp.AddJsonFile("appsettings.json", optional: true);
                configApp.AddJsonFile(
                    $"appsettings.{hostContext.HostingEnvironment.EnvironmentName}.json", 
                    optional: true);
                configApp.AddEnvironmentVariables(prefix: "PREFIX_");
                configApp.AddCommandLine(args);
            })
            .ConfigureServices((hostContext, services) =>
            {
                services.AddSingleton(new CommandLineArgs { Args = param });
                services.AddHostedService<LifetimeEventsHostedService>();
                services.AddHostedService<TimedHostedService>();
            })
            .ConfigureLogging((hostContext, configLogging) =>
            {
                configLogging.AddConsole();
                configLogging.AddDebug();
            })
            .UseConsoleLifetime()
            .Build();

        await host.RunAsync();
    }
}

解决服务

Resolve service

internal class TimedHostedService : IHostedService, IDisposable
{
    private readonly ILogger _logger;
    private Timer _timer;
    private readonly IConfiguration _configuration;
    private readonly CommandLineArgs _commandLineArgs;
    public TimedHostedService(ILogger<TimedHostedService> logger
        , IConfiguration configuration
        , CommandLineArgs commandLineArgs)
    {
        _logger = logger;
        _configuration = configuration;
        _commandLineArgs = commandLineArgs;
    }       
}

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