How to identify each parameter type in a C# method

问题:

I have a C# method say:

MyMethod(int num, string name, Color color, MyComplexType complex)

Using reflection, how can I distinctly identify each of the parameter types of any method? I want to perform some task by parameter type. If the type is simple int, string or boolean then I do something, if it is Color, XMLDocument, etc I do something else and if it is user defined type like MyComplexType or MyCalci etc then I want to do certain task.

I am able to retrieve all the parameters of a method using ParameterInfo and can loop through each parameter and get their types. But how can I identify each data type?

foreach (var parameter in parameters)
{
    //identify primitive types??
    //identify value types
    //identify reference types

}

Edit: this is apart of my code to create a propert grid sort of page where I want to show the parameter list with data types for the selected method. If the parameter has any userdefined type/reference type then I want to expand it further to show all the elements under it with datatypes.

回答1:

Make use of ParameterInfo.ParameterType

 using System;
 using System.Reflection;

 class parminfo
 {
    public static void mymethod (
       int int1m, out string str2m, ref string str3m)
    {
       str2m = "in mymethod";
    }

    public static int Main(string[] args)
    {
       Console.WriteLine("\nReflection.Parameterinfo");

       //Get the ParameterInfo parameter of a function.

       //Get the type.
       Type Mytype = Type.GetType("parminfo");

       //Get and display the method.
       MethodBase Mymethodbase = Mytype.GetMethod("mymethod");
       Console.Write("\nMymethodbase = " + Mymethodbase);

       //Get the ParameterInfo array.
       ParameterInfo[]Myarray = Mymethodbase.GetParameters();

       //Get and display the ParameterInfo of each parameter.
       foreach (ParameterInfo Myparam in Myarray)
       {
          Console.Write ("\nFor parameter # " + Myparam.Position 
             + ", the ParameterType is - " + Myparam.ParameterType);
       }
       return 0;
    }
 }

If you need to check the System.Type once retrieved you can use IsPrimitive and IsByRef as mentioned by David. In addition you can also use IsValueType. There are a significant number of Is* properties within the System.Type class. Your best bet would be to check the MSDN documentation on each Is* property ie...IsClass states...

Gets a value indicating whether the Type is a class; that is, not a value type or interface.

Therefore one could deduce that IsValueType does not need to be called. Keep in mind that a given type can return true across multiple properties in that IsClass could return true AND IsPassByRef could return true. Perhaps provide logic for the known CLR types since those will not change and you know those ahead of time and then build in the logic for complex types as defined by the user. You could take the approach of building in the logic to do this for the CLR types as well; either way would work.

回答2:

To get the actual Type of the parameter use the ParameterType on the ParameterInfo value. With that value there are several ways you can use it to identify the type. The easiest is with a direct comparison to a known type

if (parameter.ParameterType == typeof(int)) { 
  ...
}

Or in cases where the type is not available a name match can be used (although this is a bit flakier as refactor operations may miss the string constant and silently break the application)

if (parameter.ParameterType.Name == "TheTypeName") {
  ...
}