在运行时将对象转换为另一种类型

Question

void A(object o)
{
    ...
    Assembly a = Assembly.LoadFile(...);
    Type t = a.GetType(@"namespace.className");
    MethodInfo mi = t.GetMethod(@"MethodName");
    mi.Invoke(instace, new Object[] {o});
    ....         
}

the method I need to invoke accept another type, I need to cast the object to that type, but, the type is known only at run time, so can I convert/cast object to another type known only at run time ? I can change only method A.

thank you.

Answer 1

The Reflection APIs only deal with object references. Casting a reference is an operation on that reference. It does not affect the object in any way.

For that reason it is not necessary to cast anything here. Just pass o to Invoke like you are already doing. The Reflection API validates the type of o and passes it to the method you want to call.

Answer 2

The MethodInfo.Invoke(object instance, object[] arguments) is dynamic invoke. That means, the casting is made automatically. If is thrown InvalidCastException , then you pass the wrong argument or the exception is thrown from inner code and is not caused by object passed to arguments.

Answer 3

This is the code I used when I had several similar messages coming need, that needed different handling. Ordertype was a Type instance of a custom order object.

            var _ot = Activator.CreateInstance(ordertype);
            var _otconvert = ordertype.GetMethod("ConvertRequestPayload");

            object[] _params = new object[] {message};

            var objectf = _otconvert.Invoke(_ot, _params);

            var _as = Activator.CreateInstance(servicetype);
            var _method = servicetype.GetMethod("StartProcess");

            var rMessage = _method.Invoke(_as, new object[] {objectf});

Basically Activator is what you need. it allows you create objects of required type at runtime.

Answer 4

我将{object 0}更改为{dynamic 0}并且它起作用了。