如何在面向.net标准1.4的库中使用MetadataType属性

using System.ComponentModel.DataAnnotations;

public class PersonMetadata
{
    [Required(ErrorMessage = "姓名是必填项")]
    public string Name { get; set; }

    [Range(18, 99, ErrorMessage = "年龄必须在18到99之间")]
    public int Age { get; set; }
}

using System.ComponentModel.DataAnnotations;

[MetadataType(typeof(PersonMetadata))]
public class Person
{
    public string Name { get; set; }
    public int Age { get; set; }
}

using System;
using System.ComponentModel.DataAnnotations;

public class Program
{
    public static void Main()
    {
        var person = new Person();

        var validationContext = new ValidationContext(person, null, null);
        var validationResults = new List<ValidationResult>();

        bool isValid = Validator.TryValidateObject(person, validationContext, validationResults, true);

        if (!isValid)
        {
            foreach (var validationResult in validationResults)
            {
                Console.WriteLine(validationResult.ErrorMessage);
            }
        }
    }
}