Question

我有一个复杂的对象是ISerializable，我想将它序列化为一个XML文档（我宁愿不改变源代码并添加XML序列化属性的节点）。 ISerializable可以与BinaryFormatter一起使用，但没有标准的方法将它序列化为XML或Json。 Json.NET库支持将ISerializable对象序列化为json，但是该实现存在一个非常小的问题，那就是类的可序列化构造函数应该是公共的，以便Json.net检测它（参见{{3这确实使Json.net无法用于我的情况。

有没有其他方法可以将ISerializable对象序列化/反序列化为xml，Json或任何其他平面文本格式？

Answer 1

Json.NET实际上支持ISerializable类型的非公共流序列化构造函数。有关确认，请参阅DefaultContractResolver.CreateISerializableContract()的源代码。

您的实际问题是ISerializable type in question也是集合，看起来Json.NET使用数组合约而不是JsonISerializableContract来表示此类型，如显示在DefaultContractResolver.CreateContract()中：

        if (typeof(IEnumerable).IsAssignableFrom(t))
        {
            return CreateArrayContract(objectType);
        }

        if (CanConvertToString(t))
        {
            return CreateStringContract(objectType);
        }

#if !(DOTNET || PORTABLE40 || PORTABLE)
        if (!IgnoreSerializableInterface && typeof(ISerializable).IsAssignableFrom(t))
        {
            return CreateISerializableContract(objectType);
        }
#endif

要解决此问题，您可以创建自己的custom contract resolver来反转此逻辑：

public class ISerializableCollectionContractResolver : DefaultContractResolver
{
    protected override JsonContract CreateContract(Type objectType)
    {
        var contract = base.CreateContract(objectType);
        var underlyingType = Nullable.GetUnderlyingType(objectType) ?? objectType;

        if (!IgnoreSerializableInterface 
            && typeof(ISerializable).IsAssignableFrom(underlyingType)
            && contract is JsonArrayContract
            && !underlyingType.GetCustomAttributes<JsonContainerAttribute>().Any())
        {
            contract = CreateISerializableContract(objectType);
        }

        return contract;
    }
}

现在，您的自定义集合应通过其ISerializable界面进行序列化。

您可能需要cache the contract resolver for best performance。

Answer 2

DataContractSerializer和DataContractJsonSerializer都支持ISerializable。见Types Supported by the Data Contract Serializer。

例如，请考虑以下类：

[Serializable]
public class SerializableClass : ISerializable
{
    readonly int valueField;

    public SerializableClass(int valueField)
    {
        this.valueField = valueField;
    }

    public int Value { get { return valueField; } }

    #region ISerializable Members

    protected SerializableClass(SerializationInfo info, StreamingContext context)
    {
        this.valueField = info.GetInt32("valueField");
    }

    void ISerializable.GetObjectData(SerializationInfo info, StreamingContext context)
    {
        info.AddValue("valueField", valueField);
    }

    #endregion
}

以下辅助方法：

public static partial class DataContractSerializerHelper
{
    public static string SerializeXml<T>(T obj, DataContractSerializer serializer = null, XmlWriterSettings settings = null)
    {
        serializer = serializer ?? new DataContractSerializer(obj.GetType());
        using (var textWriter = new StringWriter())
        {
            settings = settings ?? new XmlWriterSettings { Indent = true, IndentChars = "    " };
            using (var xmlWriter = XmlWriter.Create(textWriter, settings))
            {
                serializer.WriteObject(xmlWriter, obj);
            }
            return textWriter.ToString();
        }
    }

    public static T DeserializeXml<T>(string xml, DataContractSerializer serializer = null)
    {
        using (var textReader = new StringReader(xml ?? ""))
        using (var xmlReader = XmlReader.Create(textReader))
        {
            return (T)(serializer ?? new DataContractSerializer(typeof(T))).ReadObject(xmlReader);
        }
    }
}

public static partial class DataContractJsonSerializerHelper
{
    private static MemoryStream GenerateStreamFromString(string value)
    {
        return new MemoryStream(Encoding.Unicode.GetBytes(value ?? ""));
    }

    public static string SerializeJson<T>(T obj, DataContractJsonSerializer serializer = null)
    {
        serializer = serializer ?? new DataContractJsonSerializer(obj.GetType());
        using (var memory = new MemoryStream())
        {
            serializer.WriteObject(memory, obj);
            memory.Seek(0, SeekOrigin.Begin);
            using (var reader = new StreamReader(memory))
            {
                return reader.ReadToEnd();
            }
        }
    }

    public static T DeserializeJson<T>(string json, DataContractJsonSerializer serializer = null)
    {
        serializer = serializer ?? new DataContractJsonSerializer(typeof(T));
        using (var stream = GenerateStreamFromString(json))
        {
            var obj = serializer.ReadObject(stream);
            return (T)obj;
        }
    }
}

然后

var test = new SerializableClass(42);

var xml = DataContractSerializerHelper.SerializeXml(test);
Debug.WriteLine(xml);

可生产

<SerializableClass xmlns:i="http://www.w3.org/2001/XMLSchema-instance" xmlns:x="http://www.w3.org/2001/XMLSchema" xmlns="http://schemas.datacontract.org/2004/07/Question38188639">
    <valueField i:type="x:int" xmlns="">42</valueField>
</SerializableClass>

和

var json = DataContractJsonSerializerHelper.SerializeJson(test);
Debug.WriteLine(json);

可生产

{"valueField":42}

如何将ISerializable对象序列化为SOAP或Json或Xml

2 个答案: