c# 解析JSON的幾種辦法

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欲成為海洋大師，必知曉海中每一滴水的真名。

剛開始只是想找一個轉換JSON數組的方法，結果在MSDN翻到一大把。

搜尋過程中免不了碰到一大堆名詞：WCF => DataContract => DataMember => DataContractJsonSerializer，然後就是不停的引入命名空間。

這一段經曆，立即讓我就聯想到了上面引用的這句存在於某小說裡面巫師的話語。靜態語言真有點令人抓狂，不停的做準備，然後才可能開始工作。

對比

.NET下幾種常見的解析JSON方法

主要類	命名空間	限制	內建LINQ支援
DataContractJsonSerializer	System.Runtime.Serialization.Json	通用	否
JavaScriptSerializer	System.Web.Script.Serialization	只能在Web環境使用	否
JsonArray、JsonObject、JsonValue	System.Json	只能在Silverlight中使用	是
JsonConvert、JArray、JObject、JValue、JProperty	Newtonsoft.Json	通用	是

 

準備資料

實體類：

    [DataContract]    public class Person    {        [DataMember(Order = 0, IsRequired = true)]        public string Name { get; set; }        [DataMember(Order = 1)]        public int Age { get; set; }        [DataMember(Order = 2)]        public bool Alive { get; set; }        [DataMember(Order = 3)]        public string[] FavoriteFilms { get; set; }        [DataMember(Order = 4)]        public Person Child { get; set; }    }

定義：

Action<object> log = o => Console.WriteLine(o);Func<int, int, int> add = (x, y) => x + y;var p1 = new Person {    Age = 12,    Alive = true,    Name = "lj",    FavoriteFilms = new[] { "Up", "Avatar" }};var p2 = new Person() { Age = 28, Name = "cy", Child = p1 };            

使用DataContractJsonSerializer

協助類：

  // using System.Runtime.Serialization.Json;        /// <summary>    /// 解析JSON，仿Javascript風格    /// </summary>    public static class JSON    {        public static T parse<T>(string jsonString)        {            using (var ms = new MemoryStream(Encoding.UTF8.GetBytes(jsonString)))            {                return (T)new DataContractJsonSerializer(typeof(T)).ReadObject(ms);            }        }        public static string stringify(object jsonObject)        {            using (var ms = new MemoryStream())            {                new DataContractJsonSerializer(jsonObject.GetType()).WriteObject(ms, jsonObject);                return Encoding.UTF8.GetString(ms.ToArray());            }        }    }

用法：

    // 序列化    var jsonString = JSON.stringify(new[] { p1, p2 });    log(jsonString == JSON.stringify(new List<Person>() { p1, p2 }));   //true    log(jsonString);    // 還原序列化，泛型集合    JSON.parse<List<Person>>(jsonString);    // 數群組轉換                JSON.parse<Person[]>(jsonString);

輸出：

[{"Name":"lj","Age":12,"Alive":true,"FavoriteFilms":["Up","Avatar"],"Child":null},{"Name":"cy","Age":28,"Alive":false,"FavoriteFilms":null,"Child":{"Name":"lj","Age":12,"Alive":true,"FavoriteFilms":["Up","Avatar"],"Child":null}}]

使用JavaScriptSerializer

  // using System.Web.Script.Serialization;        var jser    = new JavaScriptSerializer();    var json    = jser.Serialize(new List<Person>() { p1, p2 });    var persons = jser.Deserialize<List<Person>>(json);

使用Silverlight

  // using System.Json        var css = "{ \"#header\" : {background:\"red\"}, layout : [5,4,1],color:\"cyan\" }";        var style = JsonObject.Parse(css) as JsonObject;            (    from s in style    where s.Key == "color"    select (string)s.Value    ).First().ToString();    // "cyan"            // 更多操作    style["layout"][0] = 22;        var hd = style["#header"];    style["body>div+p"] = hd;    style.Remove("#header");        var bd = new JsonObject();    bd["border"] = "1px solid cyan";    style["body>div+p"]["#meta"] = bd;    style.ToString();    // {"layout":[22,4,1],"color":"cyan","body>div+p":{"background":"red","#meta":{"border":"1px solid cyan"}}}

使用JSON.NET

  // using Newtonsoft.Json;        var json = JsonConvert.SerializeObject(new[] { p1, p2 });    var persons = JsonConvert.DeserializeObject<List<Person>>(json);    var ja = JArray.Parse(jsonString);                log(ja);//注意，格式化過的輸出

輸出：

[  {    "Name": "lj",    "Age": 12,    "Alive": true,    "FavoriteFilms": [      "Up",      "Avatar"    ],    "Child": null  },  {    "Name": "cy",    "Age": 28,    "Alive": false,    "FavoriteFilms": null,    "Child": {      "Name": "lj",      "Age": 12,      "Alive": true,      "FavoriteFilms": [        "Up",        "Avatar"      ],      "Child": null    }  }]

LINQ：

    var ageCount = ja.Select(j => (int)j["Age"]).Aggregate(add);        var q = from j in ja            where !j["Name"].Value<string>().Equals("lj")            select (int)j["Age"];        log(q.Aggregate(add) == ageCount);  //false

其他：

  // 與Linq to XML 相似的嵌套建構函式：    var jo = new JObject(                    new JProperty("age", persons.Select( p => p.Age)),                    new JProperty("funny", true),                    new JProperty("array", new JArray(new[] { 2, 4, 1 }))                    );    log(jo);        // JObject 操作    var css = "{ \"#header\" : {background:\"red\"}, layout : [5,4,1] }";    var style = JObject.Parse(css);    var bd = new JObject();    bd["color"] = "1px solid cyan";    style["border"] = bd;    var hd = style["#header"];    style["body>div+p"] = hd;    hd.Parent.Remove();    style["layout"][0] = 22;    log(style);

輸出：

    {      "age": [        12,        28      ],      "funny": true,      "array": [        2,        4,        1      ]    }    {      "layout": [        22,        4,        1      ],      "border": {        "color": "1px solid cyan"      },      "body>div+p": {        "background": "red"      }    }