Net.Json 常用例子

#JsonConvert 例子

内容主要都是官方的例子，加上一些中文注释而已。 主要方便自己查询，分享一份出来.

参考文档：
https://www.newtonsoft.com/json/help/html/Introduction.htm

##JsonConver序列化
    Product product = new Product();
    
    product.Name = "Apple";
    product.ExpiryDate = new DateTime(2008, 12, 28);
    product.Price = 3.99M;
    product.Sizes = new string[] { "Small", "Medium", "Large" };
    
    string output = JsonConvert.SerializeObject(product);
    //{
    //  "Name": "Apple",
    //  "ExpiryDate": "2008-12-28T00:00:00",
    //  "Price": 3.99,
    //  "Sizes": [
    //    "Small",
    //    "Medium",
    //    "Large"
    //  ]
    //}
    
    Product deserializedProduct = JsonConvert.DeserializeObject<Product>(output);

##JsonSerializer
如果需要对对象序列化进行更多的控制。JsonSerializer能够支持Json读写流（ JsonTextReader and JsonTextWriter）

Product product = new Product();
    product.ExpiryDate = new DateTime(2008, 12, 28);
    
    JsonSerializer serializer = new JsonSerializer();
    serializer.Converters.Add(new JavaScriptDateTimeConverter());
    serializer.NullValueHandling = NullValueHandling.Ignore;
    
    using (StreamWriter sw = new StreamWriter(@"c:\json.txt"))
    using (JsonWriter writer = new JsonTextWriter(sw))
    {
        serializer.Serialize(writer, product);
        // {"ExpiryDate":new Date(1230375600000),"Price":0}
    }

## Json特性

JsonObjectAttribute - 控制Net.Json序列化对象

JsonArrayAttribute - 控制Net.Json序列化Array对象

JsonDictionaryAttribute - 控制Net.Json序列化Dictionary对象

JsonPropertyAttribute - 控制Net.Json这些属性、字段需要序列化

JsonConverterAttribute - 控制classes or fields and properties指定JsonConverter 进行序列化

JsonExtensionDataAttribute - 将不匹配的成员写入指定的容器中,具体可以看例子

JsonConstructorAttribute 指定反序列化时指定构造函数创建类

## Json回调

public class SerializationEventTestObject
    {
        // 2222
        // This member is serialized and deserialized with no change.
        public int Member1 { get; set; }
    
        // The value of this field is set and reset during and 
        // after serialization.
        public string Member2 { get; set; }
    
        // This field is not serialized. The OnDeserializedAttribute 
        // is used to set the member value after serialization.
        [JsonIgnore]
        public string Member3 { get; set; }
    
        // This field is set to null, but populated after deserialization.
        public string Member4 { get; set; }
    
        public SerializationEventTestObject()
        {
            Member1 = 11;
            Member2 = "Hello World!";
            Member3 = "This is a nonserialized value";
            Member4 = null;
        }
    
        [OnSerializing]
        internal void OnSerializingMethod(StreamingContext context)
        {
            Member2 = "This value went into the data file during serialization.";
        }
    
        [OnSerialized]
        internal void OnSerializedMethod(StreamingContext context)
        {
            Member2 = "This value was reset after serialization.";
        }
    
        [OnDeserializing]
        internal void OnDeserializingMethod(StreamingContext context)
        {
            Member3 = "This value was set during deserialization";
        }
    
        [OnDeserialized]
        internal void OnDeserializedMethod(StreamingContext context)
        {
            Member4 = "This value was set after deserialization.";
        }
    }

###测试代码
    SerializationEventTestObject obj = new SerializationEventTestObject();
    
    Console.WriteLine(obj.Member1);
    // 11
    Console.WriteLine(obj.Member2);
    // Hello World!
    Console.WriteLine(obj.Member3);
    // This is a nonserialized value
    Console.WriteLine(obj.Member4);
    // null
    
    string json = JsonConvert.SerializeObject(obj, Formatting.Indented);
    // {
    //   "Member1": 11,
    //   "Member2": "This value went into the data file during serialization.",
    //   "Member4": null
    // }
    
    Console.WriteLine(obj.Member1);
    // 11
    Console.WriteLine(obj.Member2);
    // This value was reset after serialization.
    Console.WriteLine(obj.Member3);
    // This is a nonserialized value
    Console.WriteLine(obj.Member4);
    // null
    
    obj = JsonConvert.DeserializeObject<SerializationEventTestObject>(json);
    
    Console.WriteLine(obj.Member1);
    // 11
    Console.WriteLine(obj.Member2);
    // This value went into the data file during serialization.
    Console.WriteLine(obj.Member3);
    // This value was set during deserialization
    Console.WriteLine(obj.Member4);
    // This value was set after deserialization.

## Json 错误处理

###方法1 JsonConvert 委托

List<string> errors = new List<string>();
    
    List<DateTime> c = JsonConvert.DeserializeObject<List<DateTime>>(@"[
          '2009-09-09T00:00:00Z',
          'I am not a date and will error!',
          [
            1
          ],
          '1977-02-20T00:00:00Z',
          null,
          '2000-12-01T00:00:00Z'
        ]",
        new JsonSerializerSettings
        {
            Error = delegate(object sender, ErrorEventArgs args)
            {
                errors.Add(args.ErrorContext.Error.Message);
                args.ErrorContext.Handled = true;
            },
            Converters = { new IsoDateTimeConverter() }
        });
    
    // 2009-09-09T00:00:00Z
    // 1977-02-20T00:00:00Z
    // 2000-12-01T00:00:00Z
    
    // The string was not recognized as a valid DateTime. There is a unknown word starting at index 0.
    // Unexpected token parsing date. Expected String, got StartArray.
    // Cannot convert null value to System.DateTime.

###方法2 JsonSerializer 委托
    List<string> errors = new List<string>();
    
    JsonSerializer serializer = new JsonSerializer();
    serializer.Error += delegate(object sender, ErrorEventArgs args)
    {
        // only log an error once
        if (args.CurrentObject == args.ErrorContext.OriginalObject)
        {
            errors.Add(args.ErrorContext.Error.Message);
        }
    };

###方法3 OnErrorAttribute
    public class PersonError
    {
        private List<string> _roles;
    
        public string Name { get; set; }
        public int Age { get; set; }
    
        public List<string> Roles
        {
            get
            {
                if (_roles == null)
                {
                    throw new Exception("Roles not loaded!");
                }
    
                return _roles;
            }
            set { _roles = value; }
        }
    
        public string Title { get; set; }
    
        [OnError]
        internal void OnError(StreamingContext context, ErrorContext errorContext)
        {
            errorContext.Handled = true;
        }
    }

PersonError person = new PersonError
    {
        Name = "George Michael Bluth",
        Age = 16,
        Roles = null,
        Title = "Mister Manager"
    };
    
    string json = JsonConvert.SerializeObject(person, Formatting.Indented);
    
    Console.WriteLine(json);
    //{
    //  "Name": "George Michael Bluth",
    //  "Age": 16,
    //  "Title": "Mister Manager"
    //}

## 自定义转换器CustomCreationConverter

public interface IPerson
    {
        string FirstName { get; set; }
        string LastName { get; set; }
        DateTime BirthDate { get; set; }
    }
    
    public class Employee : IPerson
    {
        public string FirstName { get; set; }
        public string LastName { get; set; }
        public DateTime BirthDate { get; set; }
    
        public string Department { get; set; }
        public string JobTitle { get; set; }
    }
    
    public class PersonConverter : CustomCreationConverter<IPerson>
    {
        public override IPerson Create(Type objectType)
        {
            return new Employee();
        }
    }

----------

//[
    //  {
    //    "FirstName": "Maurice",
    //    "LastName": "Moss",
    //    "BirthDate": "1981-03-08T00:00Z",
    //    "Department": "IT",
    //    "JobTitle": "Support"
    //  },
    //  {
    //    "FirstName": "Jen",
    //    "LastName": "Barber",
    //    "BirthDate": "1985-12-10T00:00Z",
    //    "Department": "IT",
    //    "JobTitle": "Manager"
    //  }
    //]
    
    List<IPerson> people = JsonConvert.DeserializeObject<List<IPerson>>(json, new PersonConverter());
    
    IPerson person = people[0];
    
    Console.WriteLine(person.GetType());
    // Newtonsoft.Json.Tests.Employee
    
    Console.WriteLine(person.FirstName);
    // Maurice
    
    Employee employee = (Employee)person;
    
    Console.WriteLine(employee.JobTitle);
    // Support

## 序列化跟踪日志

Staff staff = new Staff();
    staff.Name = "Arnie Admin";
    staff.Roles = new List<string> { "Administrator" };
    staff.StartDate = new DateTime(2000, 12, 12, 12, 12, 12, DateTimeKind.Utc);
    
    ITraceWriter traceWriter = new MemoryTraceWriter();
    
    JsonConvert.SerializeObject(
        staff,
        new JsonSerializerSettings { TraceWriter = traceWriter, Converters = { new JavaScriptDateTimeConverter() } });
    
    Console.WriteLine(traceWriter);
    // 2012-11-11T12:08:42.761 Info Started serializing Newtonsoft.Json.Tests.Serialization.Staff. Path ''.
    // 2012-11-11T12:08:42.785 Info Started serializing System.DateTime with converter Newtonsoft.Json.Converters.JavaScriptDateTimeConverter. Path 'StartDate'.
    // 2012-11-11T12:08:42.791 Info Finished serializing System.DateTime with converter Newtonsoft.Json.Converters.JavaScriptDateTimeConverter. Path 'StartDate'.
    // 2012-11-11T12:08:42.797 Info Started serializing System.Collections.Generic.List`1[System.String]. Path 'Roles'.
    // 2012-11-11T12:08:42.798 Info Finished serializing System.Collections.Generic.List`1[System.String]. Path 'Roles'.
    // 2012-11-11T12:08:42.799 Info Finished serializing Newtonsoft.Json.Tests.Serialization.Staff. Path ''.
    // 2013-05-18T21:38:11.255 Verbose Serialized JSON: 
    // {
    //   "Name": "Arnie Admin",
    //   "StartDate": new Date(
    //     976623132000
    //   ),
    //   "Roles": [
    //     "Administrator"
    //   ]
    // }

### 自定义序列化跟踪日志
    public class NLogTraceWriter : ITraceWriter
    {
        private static readonly Logger Logger = LogManager.GetLogger("NLogTraceWriter");
    
        public TraceLevel LevelFilter
        {
            // trace all messages. nlog can handle filtering
            get { return TraceLevel.Verbose; }
        }
    
        public void Trace(TraceLevel level, string message, Exception ex)
        {
            LogEventInfo logEvent = new LogEventInfo
            {
                Message = message,
                Level = GetLogLevel(level),
                Exception = ex
            };
    
            // log Json.NET message to NLog
            Logger.Log(logEvent);
        }
    
        private LogLevel GetLogLevel(TraceLevel level)
        {
            switch (level)
            {
                case TraceLevel.Error:
                    return LogLevel.Error;
                case TraceLevel.Warning:
                    return LogLevel.Warn;
                case TraceLevel.Info:
                    return LogLevel.Info;
                case TraceLevel.Off:
                    return LogLevel.Off;
                default:
                    return LogLevel.Trace;
            }
        }
    }

#    LINQ to JSON

##解析对象
     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

##解析数组对象

string json = @"[
      'Small',
      'Medium',
      'Large'
    ]";
    
    JArray a = JArray.Parse(json);

## 创建Json
    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"
    // ]

## Linq 创建Json

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": "Annoucing 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": "Annoucing LINQ to JSON",
    //        "link": "http://james.newtonking.com/projects/json-net.aspx",
    //        "category": [
    //          "Json.NET",
    //          "LINQ"
    //        ]
    //      }
    //    ]
    //  }
    //}

## 从一个对象创建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
                }
        }
    });

## 查询Json值

string json = @"{
      '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': 'Annoucing the release of Json.NET 1.3, the MIT license and the source on CodePlex',
            'link': 'http://james.newtonking.com/projects/json-net.aspx',
            'categories': [
              'Json.NET',
              'CodePlex'
            ]
          },
          {
            'title': 'LINQ to JSON beta',
            'description': 'Annoucing LINQ to JSON',
            'link': 'http://james.newtonking.com/projects/json-net.aspx',
            'categories': [
              'Json.NET',
              'LINQ'
            ]
          }
        ]
      }
    }";
    
    JObject rss = JObject.Parse(json);
    
    string rssTitle = (string)rss["channel"]["title"];
    // James Newton-King
    
    string itemTitle = (string)rss["channel"]["item"][0]["title"];
    // Json.NET 1.3 + New license + Now on CodePlex
    
    JArray categories = (JArray)rss["channel"]["item"][0]["categories"];
    // ["Json.NET", "CodePlex"]
    
    IList<string> categoriesText = categories.Select(c => (string)c).ToList();
    // Json.NET
    // CodePlex

## Linq查询

var postTitles =
        from p in rss["channel"]["item"]
        select (string)p["title"];
    
    foreach (var item in postTitles)
    {
        Console.WriteLine(item);
    }
    
    //LINQ to JSON beta
    //Json.NET 1.3 + New license + Now on CodePlex
    
    var categories =
        from c in rss["channel"]["item"].SelectMany(i => i["categories"]).Values<string>()
        group c by c
        into g
        orderby g.Count() descending
        select new { Category = g.Key, Count = g.Count() };
    
    foreach (var c in categories)
    {
        Console.WriteLine(c.Category + " - Count: " + c.Count);
    }
    
    //Json.NET - Count: 2
    //LINQ - Count: 1
    //CodePlex - Count: 1

## 使用LInq反序列化
    string jsonText = @"{
      'short': {
        'original': 'http://www.foo.com/',
        'short': 'krehqk',
        'error': {
          'code': 0,
          'msg': 'No action taken'
        }
      }
    }";
    
    JObject json = JObject.Parse(jsonText);
    
    Shortie shortie = new Shortie
    {
        Original = (string)json["short"]["original"],
        Short = (string)json["short"]["short"],
        Error = new ShortieException
        {
            Code = (int)json["short"]["error"]["code"],
            ErrorMessage = (string)json["short"]["error"]["msg"]
        }
    };
    
    Console.WriteLine(shortie.Original);
    // http://www.foo.com/
    
    Console.WriteLine(shortie.Error.ErrorMessage);
    // No action taken

## SelectToken查询Json

JObject o = JObject.Parse(@"{
      'Stores': [
        'Lambton Quay',
        'Willis Street'
      ],
      'Manufacturers': [
        {
          'Name': 'Acme Co',
          'Products': [
            {
              'Name': 'Anvil',
              'Price': 50
            }
          ]
        },
        {
          'Name': 'Contoso',
          'Products': [
            {
              'Name': 'Elbow Grease',
              'Price': 99.95
            },
            {
              'Name': 'Headlight Fluid',
              'Price': 4
            }
          ]
        }
      ]
    }");
    
    string name = (string)o.SelectToken("Manufacturers[0].Name");
    // Acme Co
    
    decimal productPrice = (decimal)o.SelectToken("Manufacturers[0].Products[0].Price");
    // 50
    
    string productName = (string)o.SelectToken("Manufacturers[1].Products[0].Name");
    // Elbow Grease

## SelectToken用JsonPath
    JObject o = JObject.Parse(@"{
      'Stores': [
        'Lambton Quay',
        'Willis Street'
      ],
      'Manufacturers': [
        {
          'Name': 'Acme Co',
          'Products': [
            {
              'Name': 'Anvil',
              'Price': 50
            }
          ]
        },
        {
          'Name': 'Contoso',
          'Products': [
            {
              'Name': 'Elbow Grease',
              'Price': 99.95
            },
            {
              'Name': 'Headlight Fluid',
              'Price': 4
            }
          ]
        }
      ]
    }");
    
    // manufacturer with the name 'Acme Co'
    JToken acme = o.SelectToken("$.Manufacturers[?(@.Name == 'Acme Co')]");
    
    Console.WriteLine(acme);
    // { "Name": "Acme Co", Products: [{ "Name": "Anvil", "Price": 50 }] }
    
    // name of all products priced 50 and above
    IEnumerable<JToken> pricyProducts = o.SelectTokens("$..Products[?(@.Price >= 50)].Name");
    
    foreach (JToken item in pricyProducts)
    {
        Console.WriteLine(item);
    }
    // Anvil
    // Elbow Grease

## SelectToken用LINQ

IList<string> storeNames = o.SelectToken("Stores").Select(s => (string)s).ToList();
    // Lambton Quay
    // Willis Street
    
    IList<string> firstProductNames = o["Manufacturers"].Select(m => (string)m.SelectToken("Products[1].Name")).ToList();
    // null
    // Headlight Fluid
    
    decimal totalPrice = o["Manufacturers"].Sum(m => (decimal)m.SelectToken("Products[0].Price"));
    // 149.95

#XML转JSON

## SerializeXmlNode
    string xml = @"<?xml version='1.0' standalone='no'?>
    <root>
      <person id='1'>
        <name>Alan</name>
        <url>http://www.google.com</url>
      </person>
      <person id='2'>
        <name>Louis</name>
        <url>http://www.yahoo.com</url>
      </person>
    </root>";
    
    XmlDocument doc = new XmlDocument();
    doc.LoadXml(xml);
    
    string jsonText = JsonConvert.SerializeXmlNode(doc);
    //{
    //  "?xml": {
    //    "@version": "1.0",
    //    "@standalone": "no"
    //  },
    //  "root": {
    //    "person": [
    //      {
    //        "@id": "1",
    //        "name": "Alan",
    //        "url": "http://www.google.com"
    //      },
    //      {
    //        "@id": "2",
    //        "name": "Louis",
    //        "url": "http://www.yahoo.com"
    //      }
    //    ]
    //  }
    //}

## XML属性强制转换为Json

string xml = @"<person id='1'>
      <name>Alan</name>
      <url>http://www.google.com</url>
      <role>Admin1</role>
    </person>";
    
    XmlDocument doc = new XmlDocument();
    doc.LoadXml(xml);
    
    string json = JsonConvert.SerializeXmlNode(doc);
    //{
    //  "person": {
    //    "@id": "1",
    //    "name": "Alan",
    //    "url": "http://www.google.com",
    //    "role": "Admin1"
    //  }
    //}
    
    xml = @"<person xmlns:json='http://james.newtonking.com/projects/json' id='1'>
      <name>Alan</name>
      <url>http://www.google.com</url>
      <role json:Array='true'>Admin</role>
    </person>";
    
    doc = new XmlDocument();
    doc.LoadXml(xml);
    
    json = JsonConvert.SerializeXmlNode(doc);
    //{
    //  "person": {
    //    "@id": "1",
    //    "name": "Alan",
    //    "url": "http://www.google.com",
    //    "role": [
    //      "Admin"
    //    ]
    //  }
    //}

## JSON转换XML
    string json = @"{
      '?xml': {
        '@version': '1.0',
        '@standalone': 'no'
      },
      'root': {
        'person': [
          {
            '@id': '1',
            'name': 'Alan',
            'url': 'http://www.google.com'
          },
          {
            '@id': '2',
            'name': 'Louis',
            'url': 'http://www.yahoo.com'
          }
        ]
      }
    }";
    
    XmlDocument doc = (XmlDocument)JsonConvert.DeserializeXmlNode(json);
    // <?xml version="1.0" standalone="no"?>
    // <root>
    //   <person id="1">
    //     <name>Alan</name>
    //     <url>http://www.google.com</url>
    //   </person>
    //   <person id="2">
    //     <name>Louis</name>
    //     <url>http://www.yahoo.com</url>
    //   </person>
    // </root>