JSON.NET对象序列化示例教程-零度编程

JSON.NET对象序列化示例教程

2023/7/6 02:13:35

Uncategorized .NET Platform

" JSON作为一种轻量级的数据交换格式，简单灵活，被很多系统用来数据交互，作为一名.NET开发人员，JSON.NET无疑是最好的序列化框架，支持XML和JSON序列化，高性能，免费开源，支持LINQ查询。目前已被微软集成于webapi框架之中，因此，熟练掌握JSON.NET相当重要，这篇文章是零度参考官网整理的示例，通过这些示例，可以全面了解JSON.NET提供的功能。

与其它任框架一样，要使用JSON.NET框架，首先需要在您的项目中引用它，框架可以点击这里到GITHUB开源社区下载，然后根据您项目的版本直接引用newtonsoft.json.dll即可，更快捷的方法是通过NUGET提供的包管理器来进行安装，安装方式如下所示。打开VisualStudio2013，单击〖工具〗，在〖NuGet程序包管理器〗菜单下选中〖程序包管理器控制台〗，在控制台输入以下命令后，回车即可自动安装最新版。

Install-Package Newtonsoft.Json

JSON.NET框架安装完成后，就可以在您的程序中使用它，下面就是零度提供的JSON.NET使用示例，其中绿色代码表示示例的输出结果，为了便于阅读，我们通过Formatting.Indented将代码格式化输出。

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

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, InvariantCulture

6、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

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.com

8、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 Zelda

9、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.me

10、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) }

string json = @{UserName: www.xcode.me,Enabled: true}; User user = JsonConvert.DeserializeObject<User>(json); Console.WriteLine(user.UserName);

www.xcode.me

13、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。

string json = @{ 'FullName': 'Dan Deleted', 'Deleted': true, 'DeletedDate': '2013-01-20T00:00:00' };

</span><span style=""color: blue;"">try
</span><span style=""color: black;"">{
    </span><span style=""color: #2b91af;"">JsonConvert</span><span style=""color: black;"">.DeserializeObject<</span><span style=""color: #2b91af;"">Account</span><span style=""color: black;"">>(json, </span><span style=""color: blue;"">new </span><span style=""color: #2b91af;"">JsonSerializerSettings
    </span><span style=""color: black;"">{
        MissingMemberHandling = </span><span style=""color: #2b91af;"">MissingMemberHandling</span><span style=""color: black;"">.Error
    });
}
</span><span style=""color: blue;"">catch </span><span style=""color: black;"">(</span><span style=""color: #2b91af;"">JsonSerializationException </span><span style=""color: black;"">ex)
{
    </span><span style=""color: #2b91af;"">Console</span><span style=""color: black;"">.WriteLine(ex.Message);
}</span>

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

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。

    </span><span style=""color: blue;"">public string </span><span style=""color: black;"">FullName
    {
        </span><span style=""color: blue;"">get </span><span style=""color: black;"">{ </span><span style=""color: blue;"">return </span><span style=""color: black;"">FirstName + </span><span style=""color: #a31515;"">"" "" </span><span style=""color: black;"">+ LastName; }
    }
}</span>

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 }

</span><span style=""color: blue;"">public class </span><span style=""color: #2b91af;"">User
</span><span style=""color: black;"">{
    </span><span style=""color: blue;"">public string </span><span style=""color: black;"">UserName { </span><span style=""color: blue;"">get</span><span style=""color: black;"">; </span><span style=""color: blue;"">set</span><span style=""color: black;"">; }

    [</span><span style=""color: #2b91af;"">JsonConverter</span><span style=""color: black;"">(</span><span style=""color: blue;"">typeof</span><span style=""color: black;"">(</span><span style=""color: #2b91af;"">StringEnumConverter</span><span style=""color: black;"">))]
    </span><span style=""color: blue;"">public </span><span style=""color: #2b91af;"">UserStatus </span><span style=""color: black;"">Status { </span><span style=""color: blue;"">get</span><span style=""color: black;"">; </span><span style=""color: blue;"">set</span><span style=""color: black;"">; }
}</span>

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; }

    [</span><span style=""color: #2b91af;"">JsonProperty</span><span style=""color: black;"">]
    </span><span style=""color: blue;"">public string </span><span style=""color: black;"">Name { </span><span style=""color: blue;"">get</span><span style=""color: black;"">; </span><span style=""color: blue;"">set</span><span style=""color: black;"">; }

    [</span><span style=""color: #2b91af;"">JsonProperty</span><span style=""color: black;"">]
    </span><span style=""color: blue;"">public int </span><span style=""color: black;"">Size { </span><span style=""color: blue;"">get</span><span style=""color: black;"">; </span><span style=""color: blue;"">set</span><span style=""color: black;"">; }
}</span>

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; }

    [</span><span style=""color: #2b91af;"">JsonProperty</span><span style=""color: black;"">(</span><span style=""color: #a31515;"">""release_date""</span><span style=""color: black;"">)]
    </span><span style=""color: blue;"">public </span><span style=""color: #2b91af;"">DateTime </span><span style=""color: black;"">ReleaseDate { </span><span style=""color: blue;"">get</span><span style=""color: black;"">; </span><span style=""color: blue;"">set</span><span style=""color: black;"">; }
}</span>

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; }

    [</span><span style=""color: #2b91af;"">JsonProperty</span><span style=""color: black;"">(Order = 1)]
    </span><span style=""color: blue;"">public string </span><span style=""color: black;"">LastName { </span><span style=""color: blue;"">get</span><span style=""color: black;"">; </span><span style=""color: blue;"">set</span><span style=""color: black;"">; }
}</span>

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; }

    [</span><span style=""color: #2b91af;"">JsonProperty</span><span style=""color: black;"">(Required = </span><span style=""color: #2b91af;"">Required</span><span style=""color: black;"">.AllowNull)]
    </span><span style=""color: blue;"">public </span><span style=""color: #2b91af;"">DateTime</span><span style=""color: black;"">? ReleaseDate { </span><span style=""color: blue;"">get</span><span style=""color: black;"">; </span><span style=""color: blue;"">set</span><span style=""color: black;"">; }
}</span>

string json = @{ 'Name': 'Starcraft III', 'ReleaseDate': null }; Videogame starcraft = JsonConvert.DeserializeObject<Videogame>(json); Console.WriteLine(starcraft.Name);

Starcraft III

23、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; }

    [</span><span style=""color: #2b91af;"">JsonProperty</span><span style=""color: black;"">(NullValueHandling = </span><span style=""color: #2b91af;"">NullValueHandling</span><span style=""color: black;"">.Ignore)]
    </span><span style=""color: blue;"">public </span><span style=""color: #2b91af;"">DateTime</span><span style=""color: black;"">? LaunchDate { </span><span style=""color: blue;"">get</span><span style=""color: black;"">; </span><span style=""color: blue;"">set</span><span style=""color: black;"">; }
}</span>

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);

以上就是JSON.NET的序列化和反序列化示例，下一篇博客将总结JSON.NET与LINQ的结合，希望对您有所帮助。"