json.net使用说明二

1、使用JSON.NET序列化对象public class Account{ ???public string Email { get; set; } ???public bool Active { get; set; } ???public DateTime CreatedDate { get; set; } ???public IList<string> Roles { get; set; }}Account account = new Account{ ???Email = "james@example.com", ???Active = true, ???CreatedDate = new DateTime(2013, 1, 20, 0, 0, 0, DateTimeKind.Utc), ???Roles = new List<string> { "User", "Admin" }};string json = JsonConvert.SerializeObject(account, Formatting.Indented);Console.WriteLine(json);{ ?"Email": "james@example.com", ?"Active": true, ?"CreatedDate": "2013-01-20T00:00:00Z", ?"Roles": [ ???"User", ???"Admin" ?]}2、使用JSON.NET序列化List集合List<string> videogames = new List<string> { "零度", "分享", "编程之美" };string json = JsonConvert.SerializeObject(videogames);Console.WriteLine(json);["零度","分享","编程之美"]3、使用JSON.NET序列化dictionary字典var points = new Dictionary<string, int> { { "James", 9001 }, { "Jo", 3474 }, { "Jess", 11926 } };string json = JsonConvert.SerializeObject(points, Formatting.Indented);Console.WriteLine(json);{ ?"James": 9001, ?"Jo": 3474, ?"Jess": 11926}4、将序列化结果保存到指定的文件public class Movie{ ???public string Name { get; set; } ???public int Year { get; set; }}Movie movie = new Movie { Name = "Bad Boys", Year = 1995 };using (StreamWriter file = File.CreateText(@"e:\movie.json")){ ???JsonSerializer serializer = new JsonSerializer(); ???serializer.Serialize(file, movie);}5、基于枚举类型的JsonConverters转换器public enum StringComparison { CurrentCulture = 0, CurrentCultureIgnoreCase = 1, InvariantCulture = 2 }List<StringComparison> stringComparisons = new List<StringComparison> { ????StringComparison.CurrentCulture, ???StringComparison.InvariantCulture };string jsonWithoutConverter = JsonConvert.SerializeObject(stringComparisons);Console.WriteLine(jsonWithoutConverter);[0,2]string jsonWithConverter = JsonConvert.SerializeObject(stringComparisons, new StringEnumConverter());Console.WriteLine(jsonWithConverter);["CurrentCulture","InvariantCulture"]var result = JsonConvert.DeserializeObject<List<StringComparison>>(jsonWithConverter, new StringEnumConverter());Console.WriteLine(string.Join(", ", result.Select(c => c.ToString())));CurrentCulture, InvariantCulture6、通过JRaw将JS函数序列化到JSON中public class JavaScriptSettings{ ???public JRaw OnLoadFunction { get; set; } ???public JRaw OnUnloadFunction { get; set; }}JavaScriptSettings settings = new JavaScriptSettings{ ???OnLoadFunction = new JRaw("OnLoad"), ???OnUnloadFunction = new JRaw("function(e) { alert(e); }")};string json = JsonConvert.SerializeObject(settings, Formatting.Indented);Console.WriteLine(json);{ ?"OnLoadFunction": OnLoad, ?"OnUnloadFunction": function(e) { alert(e); }}7、使用JSON.NET反序列化对象public class Account{ ???public string Email { get; set; } ???public bool Active { get; set; } ???public DateTime CreatedDate { get; set; } ???public IList<string> Roles { get; set; }}string json = @"{ ??‘Email‘: ‘james@example.com‘, ??‘Active‘: true, ??‘CreatedDate‘: ‘2013-01-20T00:00:00Z‘, ??‘Roles‘: [ ????‘User‘, ????‘Admin‘ ??] }";Account account = JsonConvert.DeserializeObject<Account>(json);Console.WriteLine(account.Email);james@example.com8、使用JSON.NET反序列化List集合string json = @"[‘Starcraft‘,‘Halo‘,‘Legend of Zelda‘]";List<string> videogames = JsonConvert.DeserializeObject<List<string>>(json);Console.WriteLine(string.Join(", ", videogames));Starcraft, Halo, Legend of Zelda9、使用JSON.NET反序列化dictionary字典string json = @"{‘href‘: ‘www.xcode.me‘,‘target‘: ‘_blank‘}";var htmlAttributes = JsonConvert.DeserializeObject<Dictionary<string, string>>(json);Console.WriteLine(htmlAttributes["href"]);www.xcode.me10、序列化var匿名类型有时候，我们并不需要先定义一个类，然后new一个对象后再进行序列化，JSON.NET支持匿名类型的序列化和反序列化。var definition = new { Name = "零度编程", Site = "www.xcode.me" };var json = JsonConvert.SerializeObject(definition);Console.WriteLine(json);{ "Name": "零度编程", "Site": "www.xcode.me" }var definition = new { Name = "", Site = "" };string json = @"{‘Name‘:‘零度编程‘,‘Site‘:‘www.xcode.me‘}";var webSite = JsonConvert.DeserializeAnonymousType(json, definition);Console.WriteLine(webSite.Name);零度编程11、用新JSON字符串填充指定对象的属性值Account account = new Account{ ???Email = "james@example.com", ???Active = true, ???CreatedDate = new DateTime(2013, 1, 20, 0, 0, 0, DateTimeKind.Utc), ???Roles = new List<string>{"User","Admin"}};string json = @"{‘Active‘: false, ‘Roles‘: [‘Expired‘]}";JsonConvert.PopulateObject(json, account);Console.WriteLine(account.Active);false上面的示例中，account对象的Active值首次设置为true，可通过PopulateObject方法通过json字符串重新填充Active属性和Roles属性。12、使用JSON.NET反序列化时可指定构造函数首先我们定义如下的类型，我们希望JSON.NET反序列化对象时使用第2个构造函数，我们将第一个默认构造函数屏蔽，标记为私有private修饰符。第2个构造函数需要指定一个website对象作为参数，如果提供的参数为null则抛出异常：public class Website{ ???public string Url { get; set; } ???private Website() ???{ ???} ???public Website(Website website) ???{ ???????if (website == null) throw new ArgumentNullException("website"); ???????Url = website.Url; ???}}现在使用一般的方式反序列化一个JSON字符串。string json = @"{‘Url‘:‘http://www.xcode.me‘}";try{ ???JsonConvert.DeserializeObject<Website>(json);}catch (Exception ex){ ???Console.WriteLine(ex);}Value cannot be null.Parameter name: website我们发现该序列化方法抛出了异常，并没有按照我们预想的方式进行反序列化，JSON.NET提供如下的方式指定公有构造函数。Website website = JsonConvert.DeserializeObject<Website>(json, new JsonSerializerSettings{ ???ConstructorHandling = ConstructorHandling.AllowNonPublicDefaultConstructor});Console.WriteLine(website.Url);http://www.xcode.me另外，JSON.NET提供了指定任何构造函数的JsonConstructorAttribute特性，只需要在构造函数上标记，即可指定构造函数。public class User{ ???public string UserName { get; private set; } ???public bool Enabled { get; private set; } ???public User() ???{ ???} ???[JsonConstructor] ???public User(string userName, bool enabled) ???{ ???????UserName = userName; ???????Enabled = enabled; ???}}string json = @"{""UserName"": ""www.xcode.me"",""Enabled"": true}";User user = JsonConvert.DeserializeObject<User>(json);Console.WriteLine(user.UserName);www.xcode.me13、当对象的属性为默认值(0或null)时不序列化该属性public class Person{ ???public string Name { get; set; } ???public int Age { get; set; } ???public Person Partner { get; set; } ???public decimal? Salary { get; set; }}Person person = new Person();string jsonIncludeDefaultValues = JsonConvert.SerializeObject(person, Formatting.Indented);Console.WriteLine(jsonIncludeDefaultValues);{ ?"Name": null, ?"Age": 0, ?"Partner": null, ?"Salary": null}string json = JsonConvert.SerializeObject(person, Formatting.Indented, new JsonSerializerSettings{ ???DefaultValueHandling = DefaultValueHandling.Ignore});Console.WriteLine(json);{}14、反序列化时JSON属性与对象属性的数量必须一致默认情况下，JSON.NET反序列化并不要求JSON属性的数量与对象属性的数量相等，也就是始终保持有则序列化，无则不序列化的原则，不会抛出异常。但是，我们的需求并非这样，我们希望属性数量不等或者未提供值时，抛出异常，而不是正常反序列化，可以这样。public class Account{ ???public string FullName { get; set; } ???public bool Deleted { get; set; }}string json = @"{ ?‘FullName‘: ‘Dan Deleted‘, ?‘Deleted‘: true, ?‘DeletedDate‘: ‘2013-01-20T00:00:00‘}";try{ ???JsonConvert.DeserializeObject<Account>(json, new JsonSerializerSettings ???{ ???????MissingMemberHandling = MissingMemberHandling.Error ???});}catch (JsonSerializationException ex){ ???Console.WriteLine(ex.Message);}Could not find member ‘DeletedDate‘ on object of type ‘Account‘. Path ‘DeletedDate‘, line 4, position 23.这样，当未全部指定对象的属性时，就会抛出异常，而不是部分属性序列化。15、JSON.NET中忽略null值得处理器public class Person{ ???public string Name { get; set; } ???public int Age { get; set; } ???public Person Partner { get; set; } ???public decimal? Salary { get; set; }}Person person = new Person { Name = "Nigal Newborn", Age = 1 };string jsonIncludeNullValues = JsonConvert.SerializeObject(person, Formatting.Indented);Console.WriteLine(jsonIncludeNullValues);{ ?"Name": "Nigal Newborn", ?"Age": 1, ?"Partner": null, ?"Salary": null}string json = JsonConvert.SerializeObject(person, Formatting.Indented, new JsonSerializerSettings{ ???NullValueHandling = NullValueHandling.Ignore});Console.WriteLine(json);{ ?"Name": "Nigal Newborn", ?"Age": 1}在上面的示例中，默认情况下JSON.NET会将对象的null属性值序列化为JSON中null值。当对象属性值为null时，可忽略序列化，只需要指定NullValueHandling即可，另外有一种场景是，当对象属性值为null时，需要替换为空字符串双引号，如何替换，请点击这里参阅零度的文章。16、JSON.NET中循环引用的处理方法有的对象具有循环引用，对象的属性是对象本身，这会导致JSON.NET进入无限死循环，我们需要指定ReferenceLoopHandling打破这种循环引用。public class Employee{ ???public string Name { get; set; } ???public Employee Manager { get; set; }}Employee joe = new Employee { Name = "Joe User" };Employee mike = new Employee { Name = "Mike Manager" };joe.Manager = mike;mike.Manager = mike;string json = JsonConvert.SerializeObject(joe, Formatting.Indented, new JsonSerializerSettings{ ???ReferenceLoopHandling = ReferenceLoopHandling.Ignore});Console.WriteLine(json);{ ?"Name": "Joe User", ?"Manager": { ???"Name": "Mike Manager" ?}}17、通过ContractResolver指定属性名首字母小写通常，在.NET中属性采用PascalCase规则（首字母大写），在JavaScript中属性名使用CamelCase规则（首字母小写），我们希望序列化后的JSON字符串符合CamelCase规则，JSON.NET提供的ContractResolver可以设置属性名小写序列化，更灵活的设置请点击这里参阅零度的文章。public class Person{ ???public string FirstName { get; set; } ???public string LastName { get; set; } ???public string FullName ???{ ???????get { return FirstName + " " + LastName; } ???}}Person person = new Person { FirstName = "Sarah", LastName = "Security" };string json = JsonConvert.SerializeObject(person, Formatting.Indented, new JsonSerializerSettings{ ???ContractResolver = new CamelCasePropertyNamesContractResolver()});Console.WriteLine(json);{ ?"firstName": "Sarah", ?"lastName": "Security", ?"fullName": "Sarah Security"}18、JSON.NET中通过特性序列化枚举类型public enum UserStatus { NotConfirmed, Active, Deleted }public class User{ ???public string UserName { get; set; } ???[JsonConverter(typeof(StringEnumConverter))] ???public UserStatus Status { get; set; }}默认情况下JSON.NET针对枚举类型输出对应的INT值，如果需要输出具有语义的字符串，可指定JsonConverter的值为StringEnumConverter类型。User user = new User { UserName = @"零度编程", Status = UserStatus.Deleted };string json = JsonConvert.SerializeObject(user, Formatting.Indented);Console.WriteLine(json);{ ?"UserName": "零度编程", ?"Status": "Deleted"}19、指定需要序列化的属性通过JsonProperty指定哪些字段应该被序列化，需要序列化则标记，不需要序列化则取消标记。[JsonObject(MemberSerialization.OptIn)]public class File{ ???//Id不需要序列化 ???public Guid Id { get; set; } ???[JsonProperty] ???public string Name { get; set; } ???[JsonProperty] ???public int Size { get; set; }}File file = new File{ ???Id = Guid.NewGuid(), ???Name = "xcode.pdf", ???Size = 50 * 1024};string json = JsonConvert.SerializeObject(file, Formatting.Indented);Console.WriteLine(json);{ ?"Name": "xcode.pdf", ?"Size": 51200}20、序列化对象时指定属性名序列化对象时，可标记属性的JsonProperty特性，并指定需要序列化为JSON时应有的属性名。public class Videogame{ ???[JsonProperty("name")] ???public string Name { get; set; } ???[JsonProperty("release_date")] ???public DateTime ReleaseDate { get; set; }}Videogame starcraft = new Videogame{ ???Name = "Starcraft", ???ReleaseDate = new DateTime(1998, 1, 1)};string json = JsonConvert.SerializeObject(starcraft, Formatting.Indented);Console.WriteLine(json);{ ?"name": "Starcraft", ?"release_date": "1998-01-01T00:00:00"}21、序列化时指定属性在JSON中的顺序public class Person{ ???[JsonProperty(Order = 2)] ???public string FirstName { get; set; } ???[JsonProperty(Order = 1)] ???public string LastName { get; set; }}Person person = new Person { FirstName = "零度", LastName = "编程" };string json = JsonConvert.SerializeObject(person, Formatting.Indented);Console.WriteLine(json);{ ?"LastName": "编程", ?"FirstName": "零度"}22、反序列化指定属性是否必须有值必须不为null在反序列化一个JSON时，可通过JsonProperty特性的Required指定反序列化行为，当反序列化行为与指定的行为不匹配时，JSON.NET将抛出异常，Required是枚举，Required.Always表示属性必须有值切不能为null，Required.AllowNull表示属性必须有值，但允许为null值。public class Videogame{ ???[JsonProperty(Required = Required.Always)] ???public string Name { get; set; } ???[JsonProperty(Required = Required.AllowNull)] ???public DateTime? ReleaseDate { get; set; }}string json = @"{ ???‘Name‘: ‘Starcraft III‘, ???‘ReleaseDate‘: null ?}";Videogame starcraft = JsonConvert.DeserializeObject<Videogame>(json);Console.WriteLine(starcraft.Name);Starcraft III23、通过特性指定null值忽略序列化public class Vessel{ ???public string Name { get; set; } ???public string Class { get; set; } ???[JsonProperty(NullValueHandling = NullValueHandling.Ignore)] ???public DateTime? LaunchDate { get; set; }}Vessel vessel = new Vessel { Name = "Red October", Class = "Typhoon" };string json = JsonConvert.SerializeObject(vessel, Formatting.Indented);Console.WriteLine(json);{ ?"Name": "Red October", ?"Class": "Typhoon"}24、忽略不需要序列化的属性并不是对象所有属性都要参与序列化，我们可以使用JsonIgnore特性排除不需要序列化的属性，下面示例中的PasswordHash将被忽略。public class Account{ ???public string FullName { get; set; } ???public string EmailAddress { get; set; } ???[JsonIgnore] ???public string PasswordHash { get; set; }}Account account = new Account{ ???FullName = "admin", ???EmailAddress = "admin@xcode.me", ???PasswordHash = "VHdlZXQgJ1FASmFtZXNOSw=="};string json = JsonConvert.SerializeObject(account);Console.WriteLine(json);{"FullName":"admin","EmailAddress":admin@xcode.me}25、通过特性指定属性的默认序列化值当属性没有赋值时，默认值一般是null或者0，我们可通过DefaultValue特性改变默认值，可用指定的字符替换，而不是输出null。public class Customer{ ???public string FirstName { get; set; } ???[DefaultValue("")] ???public string LastName { get; set; }}{"FirstName":null,"LastName":""}26、序列化或反序列化时指定日期时间格式JSON.NET中提供一个名为JsonSerializerSettings的设置对象，可通过此对象设置很多序列化和反序列化的行为，如果要设置JSON.NET序列化输出的日期时间格式，只需要指定格式化字符串即可。默认序列化行为，日期时间格式如下：public class Customer{ ???public string FirstName { get; set; } ???public string LastName { get; set; } ???public DateTime CreateDate { get; set; }}var custom = new Customer { FirstName = "零度", LastName = "编程", CreateDate = DateTime.Now };string json = JsonConvert.SerializeObject(custom, Formatting.Indented);Console.WriteLine(json);{ ?"FirstName": "零度", ?"LastName": "编程", ?"CreateDate": "2015-08-24T17:19:39.0227502+08:00"}通过JsonSerializerSettings的DateFormatString属性指定日期时间格式：JsonSerializerSettings settings = new JsonSerializerSettings();settings.DateFormatString = "yyyy-MM-dd HH:mm:ss";settings.Formatting = Formatting.Indented;string json = JsonConvert.SerializeObject(custom, settings);Console.WriteLine(json);{ ?"FirstName": "零度", ?"LastName": "编程", ?"CreateDate": "2015-08-24 17:23:56"}27、JSON字符串格式化默认情况下通过JsonConvert.SerializeObject(object value)序列化后的JSON是压缩格式，为了便于阅读，通常需要将JSON字符串格式化处理。var value = new Customer { FirstName = "零度", LastName = "编程"};string json = JsonConvert.SerializeObject(value);Console.WriteLine(json);{"FirstName":"零度","LastName":"编程"}以上为指定格式化，将输出压缩版JSON字符串，可通过Formatting.Indented指定格式化输出。string json = JsonConvert.SerializeObject(value, Formatting.Indented);Console.WriteLine(json);{ ?"FirstName": "零度", ?"LastName": "编程"}也可以指定JsonSerializerSettings对象的Formatting值为Formatting.Indented进行格式化，与上面的结果等效。JsonSerializerSettings settings = new JsonSerializerSettings();settings.Formatting = Formatting.Indented;string json = JsonConvert.SerializeObject(value, settings);Console.WriteLine(json);