StructureMap 默认实例和带有显式参数的附加实例答案

【问题标题】：StructureMap default instance and additional with explicit argumentsStructureMap 默认实例和带有显式参数的附加实例
【发布时间】：2012-04-18 04:48:07
【问题描述】：

我有一个接口和一个实现该接口的类。该类有一个默认的静态实例，也可以显式构造（传递参数）。

如何配置 StrucutreMap 以使默认实例为静态实例，如果我请求一个带有参数的实例，则构造一个新实例？

这是失败的测试

[TestFixture]
public class StructureMapTests
{
    [Test]
    public void Test_same_interface_default_implemenation_and_with_parameter()
    {
        IMyInterface defaultImp = new MyImpl(0);

        ObjectFactory.Initialize(x =>
                                     {
                                         x.For<IMyInterface>().Use(defaultImp);
                                         x.For<IMyInterface>().Add<MyImpl>().Ctor<int>().IsTheDefault();                                             
                                     });

        Assert.AreEqual(defaultImp, ObjectFactory.GetInstance<IMyInterface>());

        var instance1 = ObjectFactory.With("value").EqualTo(1).GetInstance<IMyInterface>();
        Assert.AreEqual(true, instance1 != defaultImp); //<-- fails here
        Assert.AreEqual(1, instance1.GetValue());

        var instance2 = ObjectFactory.With("value").EqualTo(2).GetInstance<IMyInterface>();
        Assert.AreEqual(true, instance1 != defaultImp);
        Assert.AreEqual(2, instance2.GetValue());
    }

    public interface IMyInterface
    {
        int GetValue();
    }

    public class MyImpl : IMyInterface
    {
        private int _value;

        public MyImpl(int value)
        {
            _value = value;
        }

        public int GetValue()
        {
            return _value;
        }
    }
}

【问题讨论】：

标签： c# dependency-injection ioc-container structuremap

【解决方案1】：

我认为您面临的问题是，当为同一个接口注册多个实现时，最后一个是 GetInstance 将要解决的那个。要解决此问题，您可以为配置命名。

尝试以下方法：

[TestFixture] 
public class StructureMapTests 
{ 
    [Test] 
    public void Test_same_interface_default_implemenation_and_with_parameter() 
    { 
        IMyInterface defaultImp = new MyImpl(0);

        ObjectFactory.Initialize(x =>
                                     {
                                         x.For<IMyInterface>().Add<MyInterface>().Named("withArgument").Ctor<int>().IsTheDefault();                                        
                                         x.For<IMyInterface>().Use(defaultImp).Named("default");
                                     });

        Assert.AreEqual(defaultImp, ObjectFactory.GetInstance<IMyInterface>());

        var instance1 = ObjectFactory.With("value").EqualTo(1).GetInstance<IMyInterface>("withArgument");
        Assert.AreEqual(true, instance1 is MyInterface); 
        Assert.AreEqual(1, instance1.GetValue());

        var instance2 = ObjectFactory.With("value").EqualTo(2).GetInstance<IMyInterface>("withArgument");
        Assert.AreEqual(true, instance2 is MyInterface);
        Assert.AreEqual(2, instance2.GetValue());
    }

    public interface IMyInterface
    {
        int GetValue();
    }

    private class MyInterface : IMyInterface
    {
        private int _value;

        public MyInterface(int value)
        {
            _value = value;
        }

        public int GetValue()
        {
            return _value;
        }
    }
}

【讨论】：