从 Activator.CreateInstance 创建对象后从接口访问方法

Question

如何从对象访问接口实现？

interface IGraphicsObject
{
    Draw();
    Delete();
}

我创建了 3 个类：Square、Circle 和 Triangle，它们都实现了 IGraphicsObject。然后我做类似的事情

object Shape = Activator.CreateInstance("myShapes", "Square");

然后我希望能够打字：

Shape.Draw();
Shape.Delete(); 

等等

我该怎么做？

Answer 1

投射到IGraphicsObject

IGraphicsObject Shape = (IGraphicsObject)Activator.CreateInstance("myShapes", "Square");

现在创建的实例，你可以调用接口方法

Shape.Draw();
Shape.Delete(); 

Answer 2

简单的答案是对它进行类型转换，但您可以通过以下方式做得更好：

    public interface IGraphicsObject
    {
        void Draw();
        void Delete();
    }

    public class Square : IGraphicsObject
    {
        public Square(string mysharpes, string square)
        {
        }

        // fill out...
    }

    public class Circle : IGraphicsObject
    {
        public Circle(string mysharpes, string square)
        {
        }

        // fill out...
    }

    public class Triangle : IGraphicsObject
    {
        public Triangle(string mysharpes, string square)
        {
        }

        // fill out...
    }

    public class Main
    {
        public IGraphicsObject CreateInstance<T>(string mysharpes, string square) where T : IGraphicsObject
        {
            return (IGraphicsObject) Activator.CreateInstance(typeof(T), mysharpes, square);
        }

        public void Run()
        {
            var shape1 = CreateInstance<Square>("mysharpes", "square");
            var shape2 = CreateInstance<Circle>("mysharpes", "square");
            var shape3 = CreateInstance<Triangle>("mysharpes", "square");

            Draw(shape1,shape2,shape3);
        }

        public void Draw( params IGraphicsObject[] shapes )
        {
            foreach( var shape in shapes )
               shape.Draw();
        }
    }

因此，您确保类型转换创建方法只允许实现接口的类型。