如何在运行时反映接口类型<t>

Question

我有多个数据点和每个数据点的关联数据处理器。

public interface IDataPointProcessor<T> where T : DataPointInputBase
{
    DataPointOutputBase GetOutput(T input);
}

我从文件加载数据点列表并希望使用其单个关联处理器来处理它们。

foreach (DataPointInputBase item in input.DataPoints)
{
    //assuming item coming in is of type 'X' how do I get correct processor
    var type = typeof(IDataPointProcessor<X>);
    var types = AppDomain.CurrentDomain.GetAssemblies()
                .SelectMany(s => s.GetTypes())
                .Where(p => type.IsAssignableFrom(p) && !p.IsAbstract);

    IDataPointProcessor<X> matchedType = ??

}

如何求解“X”以便实例化它并处理输入？

更新 #1 结合下面来自 Slava 和 Lucky 的答案，我得到以下结果，但它引发了异常——“对象与目标类型不匹配。”即使在调试器中这一切似乎都匹配。是否可以转换为 IDataPointProcessor 并干净地调用接口方法，即：instance.GetOutput(item);

foreach (DataPointInputBase item in input.DataPoints)
{
    Type typeGenArg = item.GetType();

    Type typeInterfaceGen = typeof(IDataPointProcessor<>).MakeGenericType(typeGenArg);

    Type type = AppDomain.CurrentDomain.GetAssemblies()
        .SelectMany(x => x.GetTypes())
        .Where(x => typeInterfaceGen.IsAssignableFrom(x) && !x.IsAbstract)
        .FirstOrDefault();

    Type genericType = typeof(IDataPointProcessor<>);

    Type dependedGenericType = genericType.MakeGenericType(typeof(DataPointInputBase));

    var method = dependedGenericType.GetMethod("GetOutput");
    var instance = Activator.CreateInstance(type);
    //currently throws:System.Reflection.TargetException: 'Object does not match target type.'
    var result = method.Invoke(instance, new object[] { item });
    //Ideally I want to do this and avoid the magic strings etc
    //var temp_output = instance.GetOutput(item);
}

更新 #2 为了让事情顺利进行，我对“Age_Input”类型进行了硬编码以验证事情是否有效。动态调用硬编码位我缺少什么？

我应该可以将实例转换为IDataPointProcessor<IDataPointInput> 并在接口上调用GetOutput()

foreach (IDataPointInput item in input.DataPoints)
{
    Type typeGenArg = item.GetType();

    Type typeInterfaceGen = typeof(IDataPointProcessor<>).MakeGenericType(typeGenArg);

    Type type = AppDomain.CurrentDomain.GetAssemblies()
        .SelectMany(x => x.GetTypes())
        .Where(x => typeInterfaceGen.IsAssignableFrom(x) && !x.IsAbstract)
        .FirstOrDefault();

    Type genericType = typeof(IDataPointProcessor<>);

    Type dependedGenericType = genericType.MakeGenericType(typeof(IDataPointInput));

    var instance = Activator.CreateInstance(type);

    if (instance is IDataPointProcessor<Age_Input>)//hard-coded
    {
        var processor = instance as IDataPointProcessor<Age_Input>;
        Age_Input temp = item as Age_Input;
        var result = processor.GetOutput(temp);
    }
    if (instance is DataPointProcessorBase<DataPointInputBase>)
    {
        //false
    }
    if (instance is IDataPointProcessor<DataPointInputBase>)
    {
        //false
    }
    if (instance is IDataPointProcessor<IDataPointInput>)
    {
        //false - shouldn't this work?
    }
}

Age_Input 是一个普通类，继承自哑基类和空接口

public class Age_Input : DataPointInputBase, IDataPointInput
{
    public int AgeExact { get; set; }
} 

public class DataPointInputBase : IDataPointInput
{
}
public interface IDataPointInput
{
}

处理器类同样简单

 public abstract class DataPointProcessorBase<T> : IDataPointProcessor<T> where T : IDataPointInput, new()
    {
        //public abstract DataPointOutputBase GetOutput(DataPointInputBase input);
        public abstract DataPointOutputBase GetOutput(T input);
    }

    public interface IDataPointInput
    {
    }

    public interface IDataPointProcessor<IDataPointInput> 
    {
        DataPointOutputBase GetOutput(IDataPointInput input);
    }

Answer 1

首先，你应该让你的界面像这样协变。

public interface IDataPointProcessor<in T> where T : DataPointInputBase
{
    DataPointOutputBase GetOutput(T input);
}

您应该检索IDataPointProcessor<>实现的类型，然后您应该创建检索到的类型的实例并调用泛型类型的方法。

Type genericType = typeof(IDataPointProcessor<>);
var types = AppDomain.CurrentDomain.GetAssemblies()
    .SelectMany(s => s.GetTypes())
    .Where(p => genericType.IsAssignableFrom(p) && !p.IsAbstract).ToList();


var dependedGenericType = genericType.MakeGenericType(typeof(DataPointInputBase));
var method = dependedGenericType.GetMethod("GetOutput");
var instance = Activator.CreateInstance(types[0]);
method.Invoke(instance, new object[] { new DataPointInputBase() });

Answer 2

通常情况下，如果您可以避免反射，通常情况会更好。我用一点点代码味道换了一个更简单的解决方案。

基本上我回到了基础并使用了哑接口，并在输入上使用了一个辅助方法，该方法返回了相应处理器的启动实例。

现在我的大反射循环被替换为：

foreach (IDataPointInput item in input)
{
    IDataPointProcessor processor = item.GetProcessor();
    IDataPointOutput output = processor.GetOutput();
}

代码味道是这样的 - 不是问题

public override IDataPointProcessor GetProcessor()
{
    return new Age_Processor(this);
}

完整代码如下

#region Interfaces
public interface IDataPointProcessor
{
    IDataPointOutput GetOutput();
}

public interface IDataPointInput
{
    IDataPointProcessor GetProcessor();
}

public interface IDataPointOutput
{
    List<string> DebugStrings { get; set; }
} 
#endregion

#region Base Classes
public abstract class DataPointProcessorBase : IDataPointProcessor
{
    public abstract IDataPointOutput GetOutput();
}

public abstract class DataPointInputBase : IDataPointInput
{
    public abstract IDataPointProcessor GetProcessor();
}

public abstract class DataPointOutputBase : IDataPointOutput
{
    public List<string> DebugStrings { get; set; }

    public DataPointOutputBase()
    {
        DebugStrings = new List<string>();
    }
} 
#endregion

public class Age_Output : DataPointOutputBase
{
}

public class Age_Input : DataPointInputBase
{
    public int AgeExact { get; set; }

    public override IDataPointProcessor GetProcessor()
    {
        return new Age_Processor(this);
    }
}

public class Age_Processor : DataPointProcessorBase
{
    public Age_Input Input { get; set; }
    public Age_Processor(Age_Input input)
    {
        Input = input;
    }

    public override IDataPointOutput GetOutput()
    {
        Age_Output output = new Age_Output();


        if (Input.AgeExact > 30)
        {
            output.DebugStrings.Add("Getting old");
        }
        else
        {
            output.DebugStrings.Add("Still young");
        }
        return output;
    }
}

public class DecisionEngine
{
    public void GetDecisions()
    {
        List<IDataPointInput> input = new List<IDataPointInput>();
        input.Add(new Age_Input { AgeExact = 44 });
        foreach (IDataPointInput item in input)
        {
            IDataPointProcessor processor = item.GetProcessor();
            IDataPointOutput output = processor.GetOutput();

        }
    }
}