从服务定位器到依赖注入

Question

从服务定位器到依赖注入

use*_*375 1 c# dependency-injection service-locator simple-injector

我准备了一些示例应用程序，基于这些应用程序，我想讨论转移到依赖注入而不是服务定位器的问题。我在DI领域还很新，所以请耐心等待。示例应用使用Simple Injector作为DI库编写。Bootstrapper中的注册按预期工作。每当我需要IMessageBox接口和新实例ComputationCores时，我都会使用它。

我阅读了一些有关DI的文章，因此我知道应该有一些Composition根目录以及它应该如何工作。但是我发现只是非常基本的示例，没有实词的复杂性。

样例代码：

public class DependencyResolver
{

    public static Func<Type, object> ResolveMe;

    public static T GetInstance<T>() where T : class
    {
        return (T)ResolveMe(typeof (T));
    }
}

public interface IMessageBox
{
    void ShowMessage(string message);
}

public class StandardMessageBox : IMessageBox
{
    public StandardMessageBox()
    {
        Console.WriteLine("StandardMessageBox constructor called...");
    }

    ~StandardMessageBox()
    {
        Console.WriteLine("StandardMessageBox destructor called...");
    }

    public void ShowMessage(string message)
    {
        Console.WriteLine(message);
    }
}

public interface IComputationCoreAlpha
{
    int RunComputation(int myParam);
}

public class SyncComputationCoreAlpha : IComputationCoreAlpha
{
    public SyncComputationCoreAlpha()
    {
        Console.WriteLine("SyncComputationCoreAlpha constructor called...");
    }

    ~SyncComputationCoreAlpha()
    {
        Console.WriteLine("SyncComputationCoreAlpha destructor called...");
    }

    public int RunComputation(int myParam)
    {
        return myParam * myParam;
    }
}

public class AsyncComputationCoreAlpha : IComputationCoreAlpha
{
    public AsyncComputationCoreAlpha()
    {
        Console.WriteLine("AsyncComputationCoreAlpha constructor called...");
    }

    ~AsyncComputationCoreAlpha()
    {
        Console.WriteLine("AsyncComputationCoreAlpha destructor called...");
    }


    public int RunComputation(int myParam)
    {
        return myParam * myParam;
    }
}

public interface IComputationCoreBeta
{
    int RunComputation(int myParam);
}

public class SyncComputationCoreBeta : IComputationCoreBeta
{
    public SyncComputationCoreBeta()
    {
        Console.WriteLine("SyncComputationCoreBeta constructor called...");
    }

    ~SyncComputationCoreBeta()
    {
        Console.WriteLine("SyncComputationCoreBeta destructor called...");
    }


    public int RunComputation(int myParam)
    {
        return myParam * myParam;
    }
}

public class AsyncComputationCoreBeta : IComputationCoreBeta
{
    public AsyncComputationCoreBeta()
    {
        Console.WriteLine("AsyncComputationCoreBeta constructor called...");
    }

    ~AsyncComputationCoreBeta()
    {
        Console.WriteLine("AsyncComputationCoreBeta destructor called...");
    }

    public int RunComputation(int myParam)
    {
        return myParam * myParam;
    }
}

public interface IProjectSubPart
{
    int DoCalculations(int myParam);
}

public class ProjectSubPart1 : IProjectSubPart
{
    public int DoCalculations(int myParam)
    {
        var messageBoxService = DependencyResolver.GetInstance<IMessageBox>();
        messageBoxService.ShowMessage("Hardly working 1...");
        var ccA = DependencyResolver.GetInstance<IComputationCoreAlpha>();
        var ccB = DependencyResolver.GetInstance<IComputationCoreAlpha>();

        return ccA.RunComputation(myParam) + ccB.RunComputation(myParam + 1);
    }
}

public class ProjectSubPart2 : IProjectSubPart
{
    public int DoCalculations(int myParam)
    {
        var messageBoxService = DependencyResolver.GetInstance<IMessageBox>();
        messageBoxService.ShowMessage("Hardly working 2...");
        var ccA = DependencyResolver.GetInstance<IComputationCoreAlpha>();

        return ccA.RunComputation(myParam * 3);
    }
}

public class ProjectSubPartN : IProjectSubPart
{
    public int DoCalculations(int myParam)
    {
        var messageBoxService = DependencyResolver.GetInstance<IMessageBox>();
        messageBoxService.ShowMessage("Hardly working N...");
        return -3;
    }
}

public class ManhattanProject
{
    public void RunProject()
    {
        var messageBoxService = DependencyResolver.GetInstance<IMessageBox>();
        messageBoxService.ShowMessage("Project started...");
        var subPart1 = new ProjectSubPart1();
        var subPart2 = new ProjectSubPart2();
        var subPartN = new ProjectSubPartN();

        var result = subPart1.DoCalculations(1) + subPart2.DoCalculations(2) + subPartN.DoCalculations(3);

        messageBoxService.ShowMessage(string.Format("Project finished with magic result {0}", result));
    }
}

public class Sample
{
    public void Run()
    {
        BootStrapper();

        var mp = DependencyResolver.GetInstance<ManhattanProject>();
        mp.RunProject();

    }

    private void BootStrapper()
    {
        var container = new Container();
        container.RegisterSingle<IMessageBox, StandardMessageBox>();
        container.Register<IComputationCoreAlpha, SyncComputationCoreAlpha>();
        container.Register<IComputationCoreBeta, AsyncComputationCoreBeta>();

        DependencyResolver.ResolveMe = container.GetInstance;
    }

}

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