はじめに

いまさらながらJsonを使うことになり、標準のJsonで使い方を調べエクステンションを使ったサンプルを作成した。

サンプルコード

Program.cs

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.IO;
using System.Threading.Tasks;

namespace JsonSample
{
    [DataContract]
    public class FriendInfo
    {
        [DataMember]
        public string Name { get; set; }
        [DataMember]
        public string Address { get; set; }
        [DataMember]
        public int Age { get; set; }
    }

    class Program
    {
        static void Main(string[] args)
        {
            var friends = new FriendInfo[]{
                new FriendInfo()
                {
                    Name = "Name1",
                    Address = "Hokkaido 1",
                    Age = 12
                },
                new FriendInfo()
                {
                    Name = "Name2",
                    Address = "Hokkaido 2",
                    Age = 13
                },
            };

            // シリアライズ
            var json = friends.ToJson();
            Console.WriteLine(json);
            // デシリアライズ
            // 無駄なオブジェクトが発生する拡張メソッドの例
            var defrie = new List<FriendInfo>().FromJson(json);

            // chocolamintさんの指摘を参考にstringのエクステンションに
            foreach (var info in json.DeserializingJson<List<FriendInfo>>())
                Console.WriteLine("Name:{0} Adress:{1} Age:{2}", info.Name, info.Address, info.Age);

            Console.ReadLine();
        }
    }
}

ClassExtention.cs

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading.Tasks;
using System.IO;
using System.Runtime.Serialization;
using System.Runtime.Serialization.Json;

namespace JsonSample
{
    public static class ClassExtension
    {
        public static string ToJson<T>(this T obj) where T : class
        {
            var serializer = new DataContractJsonSerializer(typeof(T));

            using (var stream = new MemoryStream())
            {
                serializer.WriteObject(stream, obj);
                return Encoding.UTF8.GetString(stream.ToArray());
            }

        }

        public static T FromJson<T>(this T obj, string json) where T : class
        {
            using (var stream = new MemoryStream(Encoding.UTF8.GetBytes(json)))
            {
                var serializer = new DataContractJsonSerializer(typeof(T));
                return serializer.ReadObject(stream) as T;
            }
        }
    }
}

StringExtention.cs

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading.Tasks;
using System.IO;
using System.Runtime.Serialization;
using System.Runtime.Serialization.Json;

namespace JsonSample
{
    public static class StringExtension
    {
        public static T DeserializingJson<T>(this string obj)
        {
            using (var stream = new MemoryStream(Encoding.UTF8.GetBytes(obj)))
            {
                var serializer = new DataContractJsonSerializer(typeof(T));
                return (T)serializer.ReadObject(stream);
            }
        }
    }
}