WebApi2官网学习记录---JSON与XML的序列化

时间:2023-03-08 22:08:04

JSON序列化:

WebAPI的默认序列库使用的是Json.NET,可以在Globally中配置使用DataContractJsonSerializer 进行序列化

        protected void Application_Start()
{
GlobalConfiguration.Configure(WebApiConfig.Register);
var json = GlobalConfiguration.Configuration.Formatters.JsonFormatter;
json.UseDataContractJsonSerializer = true;
}

默认情况下,所有的公共的属性和字段都能被序列化(非公共的不能),除非声明了JsonIgnore特性

public class Product
{
public string Name { get; set; }
public decimal Price { get; set; }
[JsonIgnore]
public int ProductCode { get; set; } // 不能被序列化
}

或者使用一下方式,将需要序列化的元素显示标出来

[DataContract]
public class Product
{
[DataMember]
public string Name { get; set; }
[DataMember]
public decimal Price { get; set; }
public int ProductCode { get; set; } // 不能被序列化
}

JSON序列化时的一些设置【测试好像没效果,疑惑】

  var json =  GlobalConfiguration.Configuration.Formatters.JsonFormatter;
//设置UTC时区
json.SerializerSettings.DateTimeZoneHandling = Newtonsoft.Json.DateTimeZoneHandling.Utc;
//设置缩进
json.SerializerSettings.Formatting = Newtonsoft.Json.Formatting.Indented;
//使用驼峰命名法
json.SerializerSettings.ContractResolver = new CamelCasePropertyNamesContractResolver();
//使用Microsoft JSON 时间格式("\/Date(ticks)\/")
json.SerializerSettings.DateFormatHandling= Newtonsoft.Json.DateFormatHandling.MicrosoftDateFormat;

action方法可以返回一个匿名对象,序列化成JSON(匿名对象不能序列化成XML)

 public object Get()
{
return new {
Name = "Alice",
Age = ,
Pets = new List<string> { "Fido", "Polly", "Spot" }
};
}
结果:
{"Name":"Alice","Age":,"Pets":["Fido","Polly","Spot"]}

如果从client收到一个JSON格式的对象,可以反序列化这个JSON对象成Newtonsoft.Json.Linq.JObject  类型的对象【需要时POST请求】

public void Post(JObject person)
{
string name = person["Name"].ToString();
int age = person["Age"].ToObject<int>();
}

Note:XML序列器不支持 匿名对象和JObject实例

XML序列化: 

默认使用DataContractSerializer进行xml序列化,序列化的规则如下:

  • 所有的公共属性和字段都能被序列化,使用IgnoreDataMember 特性可以将其排除
  • 私有和受保护的成员不会被序列化
  • 只读属性不会被序列化
  • 类和成员的名字被原样写入xml
  • 使用默认的xml命名空间

如果要更准确的控制序列化的内容,可以使用DataContract 特性,当出现了这个特性,将按如下规则进行序列化:

  • 只有标记了DataMember特性的字段或属性才能被序列化
  • 标记了DataMember特性的private/protected的成员也能被序列化
  • 只读属性不会被序列化
  • 改变对应的xml文件中命名空间或类的名字,使用DataContract特性
            //xml默认使用DataContractSerializer 进行序列化
var xml = GlobalConfiguration.Configuration.Formatters.XmlFormatter;
xml.UseXmlSerializer = true; //使用XmlSerializer 进行序列化
xml.Indent = true;//使用缩进
//设置指定对象使用指定的序列化器
xml.SetSerializer<Product>(new XmlSerializer(typeof(Product)));

移除JSON或XML序列化器 

void ConfigureApi(HttpConfiguration config)
{
// Remove the JSON formatter
config.Formatters.Remove(config.Formatters.JsonFormatter); // or // Remove the XML formatter
config.Formatters.Remove(config.Formatters.XmlFormatter);
}

处理对象的循环引用

默认情况下XML和JSON的序列化器会对对象的循环引用这种情况在序列化时抛出异常

JSON可以使用如下方式处理:

var json = GlobalConfiguration.Configuration.Formatters.JsonFormatter;
json.SerializerSettings.PreserveReferencesHandling =
Newtonsoft.Json.PreserveReferencesHandling.All;

举例如下:

 public class Employee
{
public string Name { get; set; }
public Department Department { get; set; }
} public class Department
{
public string Name { get; set; }
public Employee Manager { get; set; }
} public class DepartmentsController : ApiController
{
public Department Get(int id)
{
Department sales = new Department() { Name = "Sales" };
Employee alice = new Employee() { Name = "Alice", Department = sales };
sales.Manager = alice;
return sales;
}
}
结果:
{"$id":"","Name":"Sales","Manager":{"$id":"","Name":"Alice","Department":{"$ref":""}}}

XML有两种方式处理这种情况:

  1. 在DataContract特性上设置IsReference=true
 [DataContract(IsReference=true)]
public class Department
{
[DataMember]
public string Name { get; set; }
[DataMember]
public Employee Manager { get; set; }
}

2.创建一个针对这个对象的xml序列化器,设置允许循环引用

 var xml = GlobalConfiguration.Configuration.Formatters.XmlFormatter;
var dcs = new DataContractSerializer(typeof(Department), null, int.MaxValue,
false, /* preserveObjectReferences: */ true, null);
xml.SetSerializer<Department>(dcs);

测试对象的序列化

 string Serialize<T>(MediaTypeFormatter formatter, T value)
{
// Create a dummy HTTP Content.
Stream stream = new MemoryStream();
var content = new StreamContent(stream);
/// Serialize the object.
formatter.WriteToStreamAsync(typeof(T), value, stream, content, null).Wait();
// Read the serialized string.
stream.Position = ;
return content.ReadAsStringAsync().Result;
} T Deserialize<T>(MediaTypeFormatter formatter, string str) where T : class
{
// Write the serialized string to a memory stream.
Stream stream = new MemoryStream();
StreamWriter writer = new StreamWriter(stream);
writer.Write(str);
writer.Flush();
stream.Position = ;
// Deserialize to an object of type T
return formatter.ReadFromStreamAsync(typeof(T), stream, null, null).Result as T;
} // Example of use
void TestSerialization()
{
var value = new Person() { Name = "Alice", Age = }; var xml = new XmlMediaTypeFormatter();
string str = Serialize(xml, value); var json = new JsonMediaTypeFormatter();
str = Serialize(json, value); // Round trip
Person person2 = Deserialize<Person>(json, str);
}