Question

我正在编写一个执行几项任务的小框架。有些任务需要通过Ninject注入的特定属性。

假设我的基类中有以下构造函数，它代表一个任务：

protected DDPSchedulerTask(ILogger logger, List<string> platforms, IBackOfficeDataStore backOfficeDataStore, ICommonDataStore commonDataStore)
{
    _logger = logger;
    _platforms = platforms;
    _backOfficeDataStore = backOfficeDataStore;
    _commonDataStore = commonDataStore;
}

所有任务都需要这些属性，因此我使用Ninject将它们注入以下Ninject模块。

public class DDPDependencyInjectionBindingConfiguration : NinjectModule
{
    #region NinjectModule Members

    /// <summary>
    ///     Loads the module into the kernel.
    /// </summary>
    public override void Load()
    {
        Bind<Scheduler>().ToSelf(); // Make sure that the 'Scheduler' is resolved to itself.
        Bind<ILogger>().ToMethod(context => LogFactory.Create()); // Make sure that an instance of an ILogger is created through the LogFactory.

        // Straightforward binding.
        Bind<ICommonDataStore>().To<Common>();
        Bind<IBackOfficeDataStore>().To<BtDbInteract>();
        Bind<IDirectoryResolver>().To<Demo>();
    }

    #endregion
}

我的调度程序对象本身，如果链中的第一个条目需要由Ninject解析，所以我通过Ninject手动解析它。

var schedulerInstance = kernel.Get<Scheduler>();

现在，我的调度程序有一个方法可以将任务添加到列表中，因此不能使用Ninject：

var tasksList = new List<DDPSchedulerTask>
{
    new AWNFileGeneratorTask(_logger, availablePlatforms, _backOfficeDataStore, _commonDataStore)
};

然后，所有这些任务都在执行中。现在，其中一些任务确实需要额外的依赖关系，我想通过Ninject来解决，但我该怎么办呢？

在任务中，我创建了一个具有Inject属性的属性，但该对象保持为空。

[Inject]
private IDirectoryResolver directoryResolver { get; set; }

任何人都知道如何解决这个问题？

我可以将内核传递给不同的任务，但有些东西告诉我这不是正确的方法。

亲切的问候

Answer 1

您应该利用Ninject.Extensions.Factory。

只需创建一个代表您的任务工厂的界面。然后将信息传递给作为工厂的Ninject并且他将为您创建此接口的完整实现。

using System;
using System.Collections.Generic;
using Ninject;
using Ninject.Extensions.Factory;

internal class Program
{
    public static void Main(string[] args)
    {
        IKernel ninjectKernel = new StandardKernel();

        ninjectKernel.Bind<DDPSchedulerTask>().ToSelf();
        ninjectKernel.Bind<AWNFileGeneratorTask>().ToSelf();
        ninjectKernel.Bind<IDirectoryResolver>().To<DirectoryResolver>();
        ninjectKernel.Bind<ITaskFactory>().ToFactory();

        var mainTask = ninjectKernel.Get<DDPSchedulerTask>();
        mainTask.CreateDbSchedulerTask();
        mainTask.CreateAwnFileTask();

        Console.ReadLine();
    }
}

public interface ITaskFactory
{
    TTask CreateTask<TTask>() where TTask : DDPSchedulerTask;
}

public class DDPSchedulerTask
{
    private readonly ITaskFactory _tasksFactory;
    private readonly List<DDPSchedulerTask> _tasksList;

    public DDPSchedulerTask(ITaskFactory tasksFactory)
    {
        _tasksFactory = tasksFactory;

        _tasksList = new List<DDPSchedulerTask>();
    }

    public void CreateAwnFileTask()
    {
        var task = _tasksFactory.CreateTask<AWNFileGeneratorTask>();
        _tasksList.Add(task);
    }

    public void CreateDbSchedulerTask()
    {
        var task = _tasksFactory.CreateTask<DDPSchedulerTask>();
        _tasksList.Add(task);
    }
}

public class AWNFileGeneratorTask : DDPSchedulerTask
{
    [Inject]
    public IDirectoryResolver DirectoryResolver { get; set; }

    public AWNFileGeneratorTask(ITaskFactory tasksFactory)
        : base(tasksFactory)
    {
    }
}

public interface IDirectoryResolver
{
}

public class DirectoryResolver : IDirectoryResolver
{
}

@gisek 如前所述，通过财产的Giseke依赖注入不是最好的解决方案。您还可以在此示例中使用构造函数注入。

public class AWNFileGeneratorTask : DDPSchedulerTask
{
    private IDirectoryResolver _directoryResolver;

    public AWNFileGeneratorTask(ITaskFactory tasksFactory, IDirectoryResolver directoryResolver)
        : base(tasksFactory)
    {
        _directoryResolver = directoryResolver;
    }
}

额外的params注射：

public interface ITaskFactory
{
    DDPSchedulerTask CreateDDPSchedulerTask();
    AWNFileGeneratorTask CreateAWNFileGeneratorTask(string extraParam);
}

public class AWNFileGeneratorTask : DDPSchedulerTask
{
    private IDirectoryResolver _directoryResolver;
    private string _extraParam;

    public AWNFileGeneratorTask(ITaskFactory tasksFactory, IDirectoryResolver directoryResolver,
        string extraParam)
        : base(tasksFactory)
    {
        _extraParam = extraParam;
        _directoryResolver = directoryResolver;
    }
}

public void CreateAwnFileTask()
{
    var task = _tasksFactory.CreateAWNFileGeneratorTask("extra");
    _tasksList.Add(task);
}

Answer 2

在这种情况下，我通常使用工厂模式。在调度程序中，您可以将任务工厂作为依赖项。该工厂还可以有多种方法来创建不同类型的任务。

class DDPSchedulerTaskFactory : IDDPSchedulerTaskFactory
{
    DDPSchedulerTaskFactory(ILogger logger, List<string> platforms, IBackOfficeDataStore backOfficeDataStore, ICommonDataStore commonDataStore)
    {
        _logger = logger;
        _platforms = platforms;
        _backOfficeDataStore = backOfficeDataStore;
        _commonDataStore = commonDataStore;
    }

    public IDDPSchedulerTask CreateNormal(){
        return new DDPSchedulerTask(
            _logger,
            _platforms,
            _backOfficeDataStore,
            _commonDataStore);
    }

    public IDDPSchedulerTask CreateSpecial(someAdditionalParameter){
        return new AnotherDDPSchedulerTask(
            _logger,
            _platforms,
            _backOfficeDataStore,
            _commonDataStore,
            someAdditionalParameter);
    }

    public IDDPSchedulerTask CreateTaskWithDifferentDependenties(yetAnotherParameter){
        return new AnotherDDPSchedulerTask(
            _logger,
            _platforms,
            yetAnotherParameter);
    }
}

在调度程序中，您可以添加以下任务：

class Scheduler{
    IDDPSchedulerTaskFactory _taskFactory;
    public Scheduler(IDDPSchedulerTaskFactory taskFactory){
        _taskFactory = taskFactory; // factory gets all the needed dependencies for all tasks from DI
    }   
    ...

    public void ConfigureTasks(){
        _tasks.Add(_taskFactory.CreateNormal());
        _tasks.Add(_taskFactory.CreateSpecial("Some important message"));
        _tasks.Add(_taskFactory.CreateTaskWithDifferentDependenties(123));
    }
}

传递Ninject内核是一个好习惯吗？

2 个答案: