.NET(C#) Json.Net(newtonsoft)操作处理(解析)JSON数据(LINQ to JSON)

Json.Net安装使用参考文档：https://www.cjavapy.com/article/174/

1、使用LINQ for JSON

JObject o = JObject.Parse(@"{
  'CPU': 'Intel',
  'Drives': [
    'DVD read/writer',
    '500 gigabyte hard drive'
  ]
}");
string cpu = (string)o["CPU"];
// Intel
string firstDrive = (string)o["Drives"][0];
// DVD read/writer
IList<string> allDrives = o["Drives"].Select(t => (string)t).ToList();
// DVD read/writer
// 500 gigabyte hard drive

2、解析JSON

1）解析JSON文本

可以使用Parse(string)从字符串读取JSON值。

string json = @"{
  CPU: 'Intel',
  Drives: [
    'DVD read/writer',
    '500 gigabyte hard drive'
  ]
}";
JObject o = JObject.Parse(json);
string json = @"[
  'Small',
  'Medium',
  'Large'
]";
JArray a = JArray.Parse(json);

2）从文件加载JSON

using (StreamReader reader = File.OpenText(@"c:\person.json"))
{
    JObject o = (JObject)JToken.ReadFrom(new JsonTextReader(reader));
    // do stuff
}

3、创建JSON

1）手动创建JSON

一次设置一个值并创建一个对象和数组可以让您完全控制，但是它比其他选项更冗长。

JArray array = new JArray();
JValue text = new JValue("Manual text");
JValue date = new JValue(new DateTime(2000, 5, 23));
array.Add(text);
array.Add(date);
string json = array.ToString();
// [
//   "Manual text",
//   "2000-05-23T00:00:00"
// ]

2）用LINQ创建JSON

使用LINQ声明性地创建JSON对象是一种从值集合创建JSON的快速方法。

List<Post> posts = GetPosts();
JObject rss =
    new JObject(
        new JProperty("channel",
            new JObject(
                new JProperty("title", "James Newton-King"),
                new JProperty("link", "http://james.newtonking.com"),
                new JProperty("description", "James Newton-King's blog."),
                new JProperty("item",
                    new JArray(
                        from p in posts
                        orderby p.Title
                        select new JObject(
                            new JProperty("title", p.Title),
                            new JProperty("description", p.Description),
                            new JProperty("link", p.Link),
                            new JProperty("category",
                                new JArray(
                                    from c in p.Categories
                                    select new JValue(c)))))))));
Console.WriteLine(rss.ToString());
//{
//  "channel": {
//    "title": "James Newton-King",
//    "link": "http://james.newtonking.com",
//    "description": "James Newton-King\'s blog.",
//    "item": [
//      {
//        "title": "Json.NET 1.3 + New license + Now on CodePlex",
//        "description": "Announcing the release of Json.NET 1.3, the MIT license and being available on CodePlex",
//        "link": "http://james.newtonking.com/projects/json-net.aspx",
//        "category": [
//          "Json.NET",
//          "CodePlex"
//        ]
//      },
//      {
//        "title": "LINQ to JSON beta",
//        "description": "Announcing LINQ to JSON",
//        "link": "http://james.newtonking.com/projects/json-net.aspx",
//        "category": [
//          "Json.NET",
//          "LINQ"
//        ]
//      }
//    ]
//  }
//}

3）通过object创建JSON

最后一个选项是使用FromObject()方法从非JSON类型创建JSON对象。在内部，FromObject将使用JsonSerializer将对象序列化为LINQ到JSON对象，而不是文本。

下面的示例展示了如何从匿名对象创建JSON对象，但是任何.net类型都可以与FromObject一起用于创建JSON。

JObject o = JObject.FromObject(new
{
    channel = new
    {
        title = "James Newton-King",
        link = "http://james.newtonking.com",
        description = "James Newton-King's blog.",
        item =
            from p in posts
            orderby p.Title
            select new
            {
                title = p.Title,
                description = p.Description,
                link = p.Link,
                category = p.Categories
            }
    }
});