是否可以在序列化期间为类型定义自己的转换？

Question

我在一个类型上使用[DataContract] 属性使其可序列化。一些属性/字段是结构类型，我不想按原样序列化，但想严格使用自定义类型进行序列化。

如何用类型替换序列化？

Answer 1

当您在 .NET 中使用 [DataContract] 属性时，通常最终会使用 DataContractSerializer 序列化类型。 DataContractSerializer 有一个名为 DataContractSurrogate 的只读属性。该属性是一个IDataContractSurrogate 接口。 （只读属性可以在构造函数上设置，也可以通过DataContractSerializerSettings类型设置）

该接口包含在序列化期间将一种类型转换为另一种类型的逻辑。接口提供了 8 种方法，但是在序列化和反序列化期间将一种类型转换为另一种类型，您实际上只需要实现 3 个。这是实现接口的类的基本结构，您可以在其中替换类型和转换逻辑.

internal class SerializerSurrogate : IDataContractSurrogate
{
    /// <summary>
    /// Identifies a type transformation.
    /// </summary>
    /// <param name="type">The type being inspected.</param>
    /// <returns>The type to transform to. If the same type is used, transform does not happen.</returns>
    public Type GetDataContractType(Type type)
    {
        if (type == typeof(sourceType))
            return typeof(targetType);

        return type;
    }

    /// <summary>
    /// During serialization, transfrom from sourceType to targetType.
    /// </summary>
    /// <param name="obj">The object instance.</param>
    /// <param name="targetType">The source type.</param>
    /// <returns>A new object instance based on targetType.</returns>
    public object GetObjectToSerialize(object obj, Type targetType)
    {
        if (obj is sourceType)
        {
            // Create instance of targetType from the obj variable which is sourceType
            // Set the properties of the targetType, based on the (sourceType)obj variable.
            return new targetType();
        }

        return obj;
    }

    /// <summary>
    /// During deserialization, transform from targetType to sourceType.
    /// </summary>
    /// <param name="obj">The object instance.</param>
    /// <param name="targetType">The target type.</param>
    /// <returns>A new object instance based on sourceType.</returns>
    public object GetDeserializedObject(object obj, Type targetType)
    {
        if (obj is targetType)
        {
            // Create instance of sourceType from the obj variable which is targetType
            // Set the properties of the sourceType, based on the (targetType)obj variable.
            return new sourceType();
        }

        return obj;
    }

    public object GetCustomDataToExport(Type clrType, Type dataContractType)
    {
        throw new NotImplementedException();
    }

    public object GetCustomDataToExport(MemberInfo memberInfo, Type dataContractType)
    {
        throw new NotImplementedException();
    }

    public void GetKnownCustomDataTypes(Collection<Type> customDataTypes)
    {
        throw new NotImplementedException();
    }

    public Type GetReferencedTypeOnImport(string typeName, string typeNamespace, object customData)
    {
        return null;
    }

    public CodeTypeDeclaration ProcessImportedType(CodeTypeDeclaration typeDeclaration, CodeCompileUnit compileUnit)
    {
        return null;
    }
}