c# 解析JSON的几种办法

朴灿烈づ我的快乐病毒、 2022-08-26 01:19 131阅读 0赞

欲成为海洋大师，必知晓海中每一滴水的真名。

刚开始只是想找一个转换JSON数组的方法，结果在MSDN翻到一大把。

搜索过程中免不了碰到一大堆名词：WCF => DataContract => DataMember => DataContractJsonSerializer，然后就是不停的引入命名空间。

这一段经历，立即让我就联想到了上面引用的这句存在于某小说里面巫师的话语。静态语言真有点令人抓狂，不停的做准备，然后才可能开始工作。

## 对比 ##

<table>  .NET下几种常见的解析JSON方法      
 <thead> 
  <tr> 
   <th>主要类</th> 
   <th>命名空间</th> 
   <th>限制</th> 
   <th>内建LINQ支持</th> 
  </tr> 
 </thead> 
 <tbody> 
  <tr> 
   <td><a href="http://msdn.microsoft.com/zh-cn/library/system.runtime.serialization.json.datacontractjsonserializer.aspx" rel="nofollow">DataContractJsonSerializer</a></td> 
   <td><a href="http://msdn.microsoft.com/zh-cn/library/bb907644.aspx" rel="nofollow">System.Runtime.Serialization.Json</a></td> 
   <td>通用</td> 
   <td>否</td> 
  </tr> 
  <tr> 
   <td><a href="http://msdn.microsoft.com/zh-cn/library/system.web.script.serialization.javascriptserializer.aspx" rel="nofollow">JavaScriptSerializer</a></td> 
   <td><a href="http://msdn.microsoft.com/zh-cn/library/bb359469.aspx" rel="nofollow">System.Web.Script.Serialization</a></td> 
   <td>只能在Web环境使用</td> 
   <td>否</td> 
  </tr> 
  <tr> 
   <td><a href="http://msdn.microsoft.com/zh-cn/library/system.json.jsonarray%28VS.95%29.aspx" rel="nofollow">JsonArray</a>、<a href="http://msdn.microsoft.com/zh-cn/library/system.json.jsonobject%28v=VS.95%29.aspx" rel="nofollow">JsonObject</a>、<a href="http://msdn.microsoft.com/zh-cn/library/system.json.jsonvalue%28v=VS.95%29.aspx" rel="nofollow">JsonValue</a></td> 
   <td><a href="http://msdn.microsoft.com/zh-cn/library/cc626400%28v=VS.95%29.aspx" rel="nofollow">System.Json</a></td> 
   <td>只能在Silverlight中使用</td> 
   <td>是</td> 
  </tr> 
  <tr> 
   <td><a href="http://james.newtonking.com/projects/json/help/html/T_Newtonsoft_Json_JsonConvert.htm" rel="nofollow">JsonConvert</a>、<a href="http://james.newtonking.com/projects/json/help/html/T_Newtonsoft_Json_Linq_JArray.htm" rel="nofollow">JArray</a>、<a href="http://james.newtonking.com/projects/json/help/html/T_Newtonsoft_Json_Linq_JObject.htm" rel="nofollow">JObject</a>、<a href="http://james.newtonking.com/projects/json/help/html/T_Newtonsoft_Json_Linq_JValue.htm" rel="nofollow">JValue</a>、<a href="http://james.newtonking.com/projects/json/help/html/T_Newtonsoft_Json_Linq_JProperty.htm" rel="nofollow">JProperty</a></td> 
   <td><a href="http://james.newtonking.com/projects/json/help/" rel="nofollow">Newtonsoft.Json</a></td> 
   <td>通用</td> 
   <td>是</td> 
  </tr> 
 </tbody> 
</table>

## 准备数据 ##

实体类：

[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; }
        }

定义：

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 ##

帮助类：

// using System.Runtime.Serialization.Json;
        
        /// <summary>
        /// 解析JSON，仿Javascript风格
        /// </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);
        // 反序列化，泛型集合
        JSON.parse<List<Person>>(jsonString);
        // 数组转换            
        JSON.parse<Person[]>(jsonString);

输出：

## 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，格式化过的输出

输出：

[
      {
        "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：

// 与Linq to XML 相似的嵌套构造函数： 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);

输出：

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