在 .NET Core 中使用不同的构造函数参数（DI 和非 DI）注册多个 IHostedService 实例

Question

我的环境有 4 个相同的设备，我必须连接到这些设备并通过 TCP 连接请求一些参数（每个设备都有其 IP 地址）。我已经为需要一些参数（如 IP 地址、端口、轮询间隔等）的单个设备实现了 class

class 实现了 BackgroundService 接口并且有一个像下面这样的构造函数：

public RemoteDevice(RemoteDeviceConfig config, ILogger<RemoteDevice> logger)

在 class 中有一个 ExecuteAsync 方法的实现，里面有一个 while{} 循环，它完成了所有的逻辑。

我想构建一个 Worker Service 来处理 class 的多个实例，基于配置文件（例如，带有设备数组的配置文件）

在Program.cs我会做：

public static void Main(string[] args)
{
    CreateHostBuilder(args).Build().Run();
}

public static IHostBuilder CreateHostBuilder(string[] args) =>
    Host.CreateDefaultBuilder(args)
        .UseSystemd()
        .ConfigureServices((hostContext, services) =>
        {
            services.AddHostedService<RemoteDevice>(); //First device
            services.AddHostedService<RemoteDevice>(); //Second device
            ...
            services.AddHostedService<RemoteDevice>(); //n-th device

        });
...
//Methods to load configuration 
...

没有 RemoteDeviceConfig 构造函数参数，ILogger 被注入，但是如果我添加它，我不知道如何注入我的 RemoteDeviceConfigclass

我哪里错了？

我将 .NET Core 3.0 与 VS2019 和 Worker 服务模板项目一起使用。

更新 - 已接受的答案

我已经接受 @gldraphael ，我会添加一些关于答案评论中指定的日志记录部分的详细信息。

问题：在主 Worker class.

中实例化的 classes 中使用 ILogger 实现

解决方案：在 Worker class 中注入 ILoggerFactory 并使用它为 subclasses

创建记录器

DeviceMainClass和DeviceConfig分别是通用设备管理器及其配置。

Worker.cs

List<DeviceMainClass> devices;
//Pass ILoggerFactory to worker constructor for Dependency Injection
//On worker start, instantiate all subclasses and create logger for each class
public Worker(IOptions<List<DeviceConfig>> options, ILogger<Worker> logger, ILoggerFactory loggerFactory)
{
    devices = new List<DeviceMainClass>();
    foreach(var device in _config)
    {
        devices.Add(new DeviceMainClass(_loggerFactory.CreateLogger<DeviceMainClass>(),...other parameters));
    }

    _logger = logger;
    _loggerFactory = loggerFactory;
    _config = options.Value;
}

...

protected override async Task ExecuteAsync(CancellationToken stoppingToken)
{
    while (!stoppingToken.IsCancellationRequested)
    {


        //***for testing purposes only, repeats every second***
        _logger.LogInformation("Worker running at: {time}", DateTimeOffset.Now);
        await Task.Delay(1000, stoppingToken);
    }
}

DeviceMainClass

private readonly ILogger<DeviceMainClass> _logger;

//Use
public DeviceMainClass(ILogger<DeviceMainClass> logger, ...other parameters)
{
    _logger = logger;
    ...
}

Answer 1

您想做这样的事情：

appsettings.json

{
  "Devices": [
    { "Name": "D1" },
    { "Name": "D2" },
    { "Name": "D3" },
    { "Name": "D4" }
  ]
}

CreateHostBuilder():

public static IHostBuilder CreateHostBuilder(string[] args) =>
    Host.CreateDefaultBuilder(args)
        .ConfigureServices((hostContext, services) =>
        {
            services.Configure<List<DeviceConfig>>(hostContext.Configuration.GetSection("Devices"));
            services.AddHostedService<Worker>();
        });

工人：

public class Worker : BackgroundService
    {
        private readonly ILogger<Worker> _logger;
        private readonly List<DeviceConfig> config;

        public Worker(IOptions<List<DeviceConfig>> options, ILogger<Worker> logger)
        {
            config = options.Value;
            _logger = logger;
        }

        protected override async Task ExecuteAsync(CancellationToken stoppingToken)
        {
            while (!stoppingToken.IsCancellationRequested)
            {

                foreach(var device in config)
                {
                    // TODO: Process each device here
                    _logger.LogInformation("Processing device {name}", device.Name);
                }


                await Task.Delay(1000, stoppingToken);
            }
        }
    }

如果您当前的 RemoteDevice class 有状态信息，请在 worker 中创建一个 List<RemoteDevice> 并从配置中初始化。

Answer 2

因为我最近遇到了类似的问题 - 我遇到了这个老问题。

考虑使用任何成熟的 DI 容器而不是默认的默认容器。说 Autofac 它看起来像：

public class Program {
    public static void Main(string[] args) {
        Host.CreateDefaultBuilder(args)
            .UseServiceProviderFactory(new AutofacServiceProviderFactory())
            .ConfigureContainer<ContainerBuilder>(builder => { builder.RegisterType<DeviceMainClass>(); })
            .ConfigureServices(services => { services.AddHostedService<Worker>(); })
            //...
            .Build()
            .Run();
    }
}

public class DeviceConfig {
    //...
}

public class DeviceMainClass {
    private readonly ILogger<DeviceMainClass> _logger;
    private readonly DeviceConfig _deviceConfig;

    public DeviceMainClass(ILogger<DeviceMainClass> logger, DeviceConfig deviceConfig) {
        _logger = logger;
        _deviceConfig = deviceConfig;
    }
}

public class Worker : BackgroundService {
    List<DeviceMainClass> devices;

    private readonly ILogger<Worker> _logger;
    private readonly List<DeviceConfig> _config;

    public Worker(IOptions<List<DeviceConfig>> options, Func<DeviceConfig, DeviceMainClass> deviceFactory, ILogger<Worker> logger) {
        _logger = logger;
        _config = options.Value;
        devices = new List<DeviceMainClass>();
        foreach (var deviceConfig in _config) {
            //autofac automatically adds appropriate logger when calling DeviceMainClass constructor                
            devices.Add(deviceFactory(deviceConfig)); 
        }

    }
}

查看更多详情here and here。

在 .NET Core 中使用不同的构造函数参数（DI 和非 DI）注册多个 IHostedService 实例

Register multiple instances of IHostedService with different constructor parameters (DI and non-DI) in .NET Core

c#

.net

visual-studio-2019

.net-core-3.0