I可与递归子级序列化

Question

我想为一个C#类实现ISerializable，该类包含一个类似类型的子类列表。考虑以下示例：

using System;
using System.Collections.Generic;
using System.IO;
using System.Runtime.Serialization;
using System.Runtime.Serialization.Formatters.Binary;
namespace serialisation
{
    [Serializable]
    internal class Nested : ISerializable
    {
        public string Name { get; set; }
        public List<Nested> Children { get; set; }
        public Nested(string name)
        {
            Name = name;
            Children = new List<Nested>();
        }
        protected Nested(System.Runtime.Serialization.SerializationInfo info, System.Runtime.Serialization.StreamingContext context)
        {
            Name = info.GetString("Name");
            // This doesn't work:
            Nested[] children = (Nested[])info.GetValue("Children", typeof(Nested[]));
            Children = new List<Nested>(children);
            // This works:
            // Children = (List<Nested>)info.GetValue("Children", typeof(List<Nested>));
        }
        public void GetObjectData(System.Runtime.Serialization.SerializationInfo info, System.Runtime.Serialization.StreamingContext context)
        {
            info.AddValue("Name", Name);
            // This doesn't work:
            info.AddValue("Children", Children.ToArray());
            // This works:
            //info.AddValue("Children", Children);
        }
    }
    internal class Program
    {
        private static void Main(string[] args)
        {
            // Generate a hierarchy
            Nested root = new Nested("root");
            Nested child1 = new Nested("child1");
            Nested child2 = new Nested("child2");
            Nested child3 = new Nested("child3");
            child1.Children.Add(child2);
            child1.Children.Add(child3);
            root.Children.Add(child1);
            Nested deserialized;
            BinaryFormatter binaryFmt = new BinaryFormatter();
            // Serialize
            using (var fs = new FileStream("Nested.xml", FileMode.OpenOrCreate))
            {
                binaryFmt.Serialize(fs, root);
            }
            // Deserialize
            using (var fs = new FileStream("Nested.xml", FileMode.OpenOrCreate))
            {
                deserialized = (Nested)binaryFmt.Deserialize(fs);
            }
            // deserialized.Children contains one null child
            Console.WriteLine("Original Name: {0}", root.Name);
            Console.WriteLine("New Name: {0}", deserialized.Name);
        }
    }
}

在上面的示例中，Nested.GetObjectData和Nested的序列化程序构造函数被相继调用了4次。

将子项作为嵌套数组添加到序列化程序将在反序列化时返回大小正确的数组，但所有元素都将为null。

然而，将类型从Nested array更改为Nested List将在调用子级的构造函数后神奇地修复null元素。

我想知道的是：

1. 嵌套列表有什么特别之处
2. 用这样的递归结构序列化类的推荐方法是什么

更新：

似乎还有一个额外的接口，IDeserializationCallback.OnSerialization，它是在反序列化发生后调用的（调用顺序是不确定的）。您可以将反序列化的数组存储在构造函数的临时成员变量中，然后在此方法中将其分配给列表。除非我遗漏了什么，否则这似乎并不理想，因为您必须用临时变量来打乱您的实现。

Answer 1

我会选择复合模式。下面的解决方案解决了BinaryFormatter（与Main中的方法类似）和XmlSerializer方法，如果您要使用它们的话。Composite和Component将替换您的Nested类。

[Serializable()]
[XmlRoot("component", Namespace="", IsNullable=false)]
public partial class CT_Component 
{
    [XmlAttribute("name")]
    public string Name { get; set;}
}
[Serializable()]
[XmlRoot("composite", Namespace="", IsNullable=false)]
public partial class CT_Composite 
{
    [XmlElement("component", typeof(CT_Component))]
    [XmlElement("composite", typeof(CT_Composite))]
    public object[] Items { get; set; }
    [XmlAttribute("name")]
    public string Name { get; set; }
}

我从下面的xsd创建了这些类，我总是从xsd转到生成的类，因为我永远无法正确地获得属性装饰。它的要点是递归CT_Composite类型：

<xs:element name="component" type="CT_Component" />
<xs:element name="composite" type="CT_Composite" />
<xs:complexType name="CT_Component">
  <xs:attribute name="name" type="xs:string" use="required" />
</xs:complexType>
<xs:complexType name="CT_Composite" >
  <xs:choice minOccurs="1" maxOccurs="unbounded">
    <xs:element ref="component" />
    <xs:element name="composite" type="CT_Composite" />
  </xs:choice>
  <xs:attribute name="name" type="xs:string" use="required" />
</xs:complexType>

序列化代码是相同的。变量声明：

var composite = new CT_Composite() {
            Name = "root",
            Items = new object[] {
                new CT_Composite() {
                    Name = "child1",
                    Items = new object[] {
                        new CT_Component() {Name="child2"},
                        new CT_Component() {Name="child3"}
                    } } } };

如果你对模式更加正统，你可以使用：

[Serializable()]
[XmlRoot("component", Namespace="", IsNullable=false)]
public class Component {
    [XmlAttribute("name")] public string Name { get; set;}
}
[Serializable()]
[XmlRoot("composite", Namespace="", IsNullable=false)]
public class Composite : Component {
    [XmlElement("component", typeof(Component))]
    [XmlElement("composite", typeof(Composite))]
    public object[] Items { get; set; }
}