c# - 将 JsonSerializerSettings 从 JsonSerializer 复制到新的 JsonSerializer

Question

有什么方法可以从 JsonSerializer 类中取出设置并在新的 JsonSerializer 中重新实现它们？

似乎没有任何方法可以做那样的事情。我发现最好的是通过反射调用的私有(private)方法，ApplySerializerSettings。

我正在尝试从 WriteJson 方法中获取序列化器并将其复制到一个新的序列化器中，稍微调整一下。具体来说，我想替换 ContractResolver。

public override void WriteJson(JsonWriter writer, object value, JsonSerializer serializer)

Answer 1

似乎最好的方法是将所有设置复制到一个新对象中。它们有很多，所以这里有一个很好的扩展方法(从 8.0.3 开始)。

public static class JsonSerializerExtensions
{
  public static JsonSerializer DeepCopy(this JsonSerializer serializer)
  {
    var copiedSerializer = new JsonSerializer
    {
      Context = serializer.Context,
      Culture = serializer.Culture,
      ContractResolver = serializer.ContractResolver,
      ConstructorHandling = serializer.ConstructorHandling,
      CheckAdditionalContent = serializer.CheckAdditionalContent,
      DateFormatHandling = serializer.DateFormatHandling,
      DateFormatString = serializer.DateFormatString,
      DateParseHandling = serializer.DateParseHandling,
      DateTimeZoneHandling = serializer.DateTimeZoneHandling,
      DefaultValueHandling = serializer.DefaultValueHandling,
      EqualityComparer = serializer.EqualityComparer,
      FloatFormatHandling = serializer.FloatFormatHandling,
      Formatting = serializer.Formatting,
      FloatParseHandling = serializer.FloatParseHandling,
      MaxDepth = serializer.MaxDepth,
      MetadataPropertyHandling = serializer.MetadataPropertyHandling,
      MissingMemberHandling = serializer.MissingMemberHandling,
      NullValueHandling = serializer.NullValueHandling,
      ObjectCreationHandling = serializer.ObjectCreationHandling,
      PreserveReferencesHandling = serializer.PreserveReferencesHandling,
      ReferenceResolver = serializer.ReferenceResolver,
      ReferenceLoopHandling = serializer.ReferenceLoopHandling,
      StringEscapeHandling = serializer.StringEscapeHandling,
      TraceWriter = serializer.TraceWriter,
      TypeNameHandling = serializer.TypeNameHandling,
      SerializationBinder = serializer.SerializationBinder,
      TypeNameAssemblyFormatHandling = serializer.TypeNameAssemblyFormatHandling
    };
    foreach (var converter in serializer.Converters)
    {
      copiedSerializer.Converters.Add(converter);
    }
    return copiedSerializer;
  }
}

虽然很丑，但至少你只需要写一次。稍微小心一点，因为属性本​​身不会被深度复制。

下面的答案取决于您的实现情况，尤其是在解决契约(Contract)时。保留它以防万一它对某人有帮助。

---

所以，我不能完全复制设置，但我发现了一个可能需要考虑的很好的解决方法。您可以在锁定的上下文中简单地设置要更改的属性，然后再重置它们。

public override void WriteJson(JsonWriter writer, object value, JsonSerializer serializer)
{
    var thing = value as IThing;

    if (thing == null)
        throw new ArgumentException($"Writing Json failed because " + 
          "value was not a 'Thing' of type, {typeof(IThing).FullName}");

    JObject jsonThing;
    //If your solution is multithreaded,
    //and is using a shared serializer (which you probably are),
    //you should lock the serializer so that it doesn't accidentally use 
    //the "CustomObjectResolver"
    lock (serializer)
    {
        //Hold the original value(s) to reset later
        var originalContractResolver = serializer.ContractResolver;
        //Set custom value(s)
        serializer.ContractResolver = new CustomObjectResolver();
        //Serialization with custom properties
        jsonThing = JObject.FromObject(value, serializer);
        //Reset original value(s)
        serializer.ContractResolver = originalContractResolver;
    }

    //Finish serializing and write to writer.
}