如何从字符串c#中获取自定义类的类型

Question

I am trying to use GetType method for my custom class . I have the name of the class as string and i want to get type of it dynamically. I have the same name for two different classes which are located in different directories.

For Example:

MyClass.cs in Folder1:

namespace ConsoleApplication1.Folder1
{
    public class MyClass : IClass
    {
        public void PrintMe()
        {
            System.Console.WriteLine("I am Folder 1 Class");
        }
    }
}

MyClass.cs in Folder2:

namespace ConsoleApplication1.Folder2
{
    public class MyClass : IClass
    {
        public void PrintMe()
        {
            System.Console.WriteLine("I am Folder 2 Class");
        }
    }
}

Namespace is ConsoleApplication1

different classes with the same name are in the Folder1 and Folder2.

I want to get it's type from such a string:

var runtimeString = "Folder1.MyClass" 

There is method mentioned in MSDN named GetType(string fileName)

How can i get type of the file and resolve it from the serviceLocator with type on runtime like:

var typeOfMyClass = GetType(runtimeString);    
var instanceOfMyClass = ServiceLocator.Resolve<TypeOfMyClass>(); 

Answer 1

You appear to be describing a need for a factory method, something along the lines of:

public class MyClassFactory : IMyClassFactory
{
    private Dictionary<string, Action<IClass>> _factory =
        new Dictionary<string, Action<IClass>>
        {
            ["Folder1.MyClass"] = () => new ConsoleApplication1.Folder1.MyClass(),
            ["Folder2.MyClass"] = () => new ConsoleApplication1.Folder2.MyClass(),
            ...
        };

    public IClass GetClassInstance(string myClassName)
    {
        if (_factory.Contains(myClassName))
        {
            return _factory[myClassName]();
        }
        throw NoSuchClassException(myClassName);
    }
} 

Answer 2

I believe the following is what you are trying to accomplish:

    static void Main(string[] args)
    {
        var runtimeString = "Folder1.MyClass";
        IClass instanceOfMyClass = (IClass)CreateInstance(runtimeString);
        instanceOfMyClass.PrintMe();

        Console.ReadKey();
    }
    private static object CreateInstance(string className)
    {
        var type = Assembly.GetExecutingAssembly().GetTypes()
            .First(t => t.FullName.EndsWith(className));

        return Activator.CreateInstance(type);
    }

Answer 3

You may use Activator.CreateInstance() method to create an object of a class from its name string as below.

Create the Type object:

Type type1 = typeof(MyClass);

or

Type type1 = Type.GetType("MyClass");

Create an instance of that type:

Object o = Activator.CreateInstance(type1);