通过NameValuePairsValueProvider对象来获取指定前缀的Key

using System;
using System.Collections.Generic;
using System.Linq;
using System.Web.Http.ValueProviders.Providers;

namespace ConsoleApp
{
    internal class Program
    {
        private static void Main(string[] args)
        {
            var dic = new Dictionary<string, string>
            {
                {"contact.Name", "张三"},
                {"contact.PhoneNo", "123456789"},
                {"contact.EmailAddress", "zhangsan@gmail.com"},
                {"contact.Address.Province", "上海"},
                {"contact.Address.City", "上海"},
                {"contact.Address.District", "长宁区"},
                {"contact.Address.Street", "金钟路968号"}
            };
            var valueProvider = new NameValuePairsValueProvider(dic.ToArray(), null);

            // prefix=""
            Console.WriteLine("Prefix: <Empty>");
            Console.WriteLine("{0,-14}{1}", "key", "value");
            var keys = valueProvider.GetKeysFromPrefix(string.Empty);
            foreach (var item in keys)
            {
                Console.WriteLine("{0,-14}{1}", item.Key, item.Value);
            }

            // Prefix="contact"
            Console.WriteLine("Prefix: contact");
            Console.WriteLine("{0,-14}{1}", "key", "value");
            keys = valueProvider.GetKeysFromPrefix("contact");
            foreach (var item in keys)
            {
                Console.WriteLine("{0,-14}{1}", item.Key, item.Value);
            }

            // Prefix="contact"
            Console.WriteLine("Prefix: contact.Address");
            Console.WriteLine("{0,-14}{1}", "key", "value");
            keys = valueProvider.GetKeysFromPrefix("contact.Address");
            foreach (var item in keys)
            {
                Console.WriteLine("{0,-14}{1}", item.Key, item.Value);
            }

            Console.Read();
        }
    }
}