Json.Net - 从“System.Net.IPAddress"上的“ScopeId"获取值时出错

The IPAddress class is not very friendly to serialization, as you've seen. Not only will it throw a SocketException if you try to access the ScopeID field for an IPv4 address, but it will also throw if you try to access the Address field directly for an IPv6 address.

要绕过异常，您需要一个自定义 JsonConverter.转换器允许您准确地告诉 Json.Net 您希望它如何序列化和/或反序列化特定类型的对象.对于一个IPAddress，似乎最简单的方法来获得满足每个人的数据只是将其转换为它的字符串表示并返回.我们可以在转换器中做到这一点.这是我的写法:

To get around the exceptions, you will need a custom JsonConverter. A converter allows you to tell Json.Net exactly how you'd like it to serialize and/or deserialize a particular type of object. For an IPAddress, it seems the easiest way to get the data that satisfies everyone is simply to convert it to its string representation and back. We can do that in the converter. Here is how I would write it:

class IPAddressConverter : JsonConverter
{
    public override bool CanConvert(Type objectType)
    {
        return (objectType == typeof(IPAddress));
    }

    public override void WriteJson(JsonWriter writer, object value, JsonSerializer serializer)
    {
        writer.WriteValue(value.ToString());
    }

    public override object ReadJson(JsonReader reader, Type objectType, object existingValue, JsonSerializer serializer)
    {
        return IPAddress.Parse((string)reader.Value);
    }
}

很简单，就像这些事情一样.但是，这并不是故事的结局.如果您需要使用 IPEndPoint 进行往返，那么您也需要一个转换器.为什么?因为 IPEndPoint 不包含默认构造函数，所以 Json.Net 将不知道如何实例化它.幸运的是，这个转换器也不难写:

Pretty straightforward, as these things go. But, this is not the end of the story. If you need to go round-trip with your IPEndPoint, then you will need a converter for it as well. Why? Because IPEndPoint does not contain a default constructor, so Json.Net will not know how to instantiate it. Fortunately, this converter is not difficult to write either:

class IPEndPointConverter : JsonConverter
{
    public override bool CanConvert(Type objectType)
    {
        return (objectType == typeof(IPEndPoint));
    }

    public override void WriteJson(JsonWriter writer, object value, JsonSerializer serializer)
    {
        IPEndPoint ep = (IPEndPoint)value;
        JObject jo = new JObject();
        jo.Add("Address", JToken.FromObject(ep.Address, serializer));
        jo.Add("Port", ep.Port);
        jo.WriteTo(writer);
    }

    public override object ReadJson(JsonReader reader, Type objectType, object existingValue, JsonSerializer serializer)
    {
        JObject jo = JObject.Load(reader);
        IPAddress address = jo["Address"].ToObject<IPAddress>(serializer);
        int port = (int)jo["Port"];
        return new IPEndPoint(address, port);
    }
}

那么，既然我们有了转换器，我们该如何使用它们呢?这是一个演示的简单示例程序.它首先创建几个端点，使用自定义转换器将它们序列化为 JSON，然后立即使用相同的转换器再次将 JSON 反序列化回端点.

So, now that we have the converters, how do we use them? Here is a simple example program that demonstrates. It first creates a couple of endpoints, serializes them to JSON using the custom converters, then immediately deserializes the JSON back into endpoints again using the same converters.

public class Program
{
    static void Main(string[] args)
    {
        var endpoints = new IPEndPoint[]
        {
            new IPEndPoint(IPAddress.Parse("8.8.4.4"), 53),
            new IPEndPoint(IPAddress.Parse("2001:db8::ff00:42:8329"), 81)
        };

        var settings = new JsonSerializerSettings();
        settings.Converters.Add(new IPAddressConverter());
        settings.Converters.Add(new IPEndPointConverter());
        settings.Formatting = Formatting.Indented;

        string json = JsonConvert.SerializeObject(endpoints, settings);
        Console.WriteLine(json);

        var endpoints2 = JsonConvert.DeserializeObject<IPEndPoint[]>(json, settings);

        foreach (IPEndPoint ep in endpoints2)
        {
            Console.WriteLine();
            Console.WriteLine("AddressFamily: " + ep.AddressFamily);
            Console.WriteLine("Address: " + ep.Address);
            Console.WriteLine("Port: " + ep.Port);
        }
    }
}

这是输出:

[
  {
    "Address": "8.8.4.4",
    "Port": 53
  },
  {
    "Address": "2001:db8::ff00:42:8329",
    "Port": 81
  }
]

AddressFamily: InterNetwork
Address: 8.8.4.4
Port: 53

AddressFamily: InterNetworkV6
Address: 2001:db8::ff00:42:8329
Port: 81

小提琴:https://dotnetfiddle.net/tK7NKY

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