Json.Net学习笔记(八) 序列化的回调方法

Json.Net支持序列化回调方法，回调方法通过Json序列化器(JsonSerializer)可以用来操作一个对象，在它被序列化和反序列化之前或者之后.

OnSerializing
OnSerialized
OnDeserializing
OnDeserialized

为了告诉序列化器在对象的序列化生命周期中哪个方法应该被调用，需要用适当的attribute(OnSerializingAttribute, OnSerializedAttribute, OnDeserializingAttribute, OnDeserializedAttribute)来标记方法.

例如对象序列化的回调方法:

using Newtonsoft.Json;
using System.Runtime.Serialization;

 public class SerializationEventTestObject
    {
        // 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.";
        }
    }

示例对象被序列化和反序列化:

 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);
            Console.WriteLine(json);

            //{
            //  "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.