.NET XML序列化 - 存储引用，而不是对象的副本

问题描述：

在净/ C＃应用程序，我有数据结构具有相互之间的引用。
当我序列化它们，净序列化与独立的对象副本的所有引用。
在以下示例中，我试图序列化到'人'
人可能会参考其他人。

In .Net/C# Application, I have data structures which have references to each other.
When I serialize them, .Net Serializes all references with separate object copies.
In Following Example, I am trying to serialize to Array of 'Person'
A 'Person' may have reference to another person.

public class Person
{
    public string Name;
    public Person Friend;
}


Person p1 = new Person();
p1.Name = "John";


Person p2 = new Person();
p2.Name = "Mike";


p1.Friend = p2;


Person[] group = new Person[] { p1, p2 };
XmlSerializer ser = new XmlSerializer(typeof(Person[]));
using (TextWriter tw = new StreamWriter("test.xml"))
    ser.Serialize(tw,group );


//above code generates following xml


<ArrayOfPerson>
  <Person>
    <Name>John</Name>
    <Friend>
      <Name>Mike</Name>
    </Friend>
  </Person>
  <Person>
    <Name>Mike</Name>
  </Person>
</ArrayOfPerson>

在上面code，同样的'迈克'的对象是有两个地方，因为是同一个对象的两个引用。

答

这是不可能的XmlSerializer.你可以做到这一点与DataContractSerializer使用$p$pserveObjectReferences属性。你可以看看这个帖子这解释了细节。

It is not possible with XmlSerializer. You could achieve this with DataContractSerializer using the PreserveObjectReferences property. You may take a look at this post which explains the details.

下面是一个示例code：

Here's a sample code:

public class Person
{
    public string Name;
    public Person Friend;
}

class Program
{
    static void Main(string[] args)
    {
        Person p1 = new Person();
        p1.Name = "John";

        Person p2 = new Person();
        p2.Name = "Mike";
        p1.Friend = p2;
        Person[] group = new Person[] { p1, p2 };

        var serializer = new DataContractSerializer(group.GetType(), null, 
            0x7FFF /*maxItemsInObjectGraph*/, 
            false /*ignoreExtensionDataObject*/, 
            true /*preserveObjectReferences : this is where the magic happens */, 
            null /*dataContractSurrogate*/);
        serializer.WriteObject(Console.OpenStandardOutput(), group);
    }
}

这将产生以下XML：

This produces the following XML:

<ArrayOfPerson z:Id="1" z:Size="2" xmlns="http://schemas.datacontract.org/2004/07/ToDelete" xmlns:i="http://www.w3.org/2001/XMLSchema-instance" xmlns:z="http://schemas.microsoft.com/2003/10/Serialization/">
    <Person z:Id="2">
        <Friend z:Id="3">
            <Friend i:nil="true"/>
            <Name z:Id="4">Mike</Name>
        </Friend>
        <Name z:Id="5">John</Name>
    </Person>
    <Person z:Ref="3" i:nil="true"/>
</ArrayOfPerson>

现在设置 preserveObjectReferences 到假在构造函数中，你会得到这样的：

Now set PreserveObjectReferences to false in the constructor and you will get this:

<ArrayOfPerson xmlns="http://schemas.datacontract.org/2004/07/ToDelete" xmlns:i="http://www.w3.org/2001/XMLSchema-instance">
    <Person>
        <Friend>
            <Friend i:nil="true"/>
            <Name>Mike</Name>
        </Friend>
        <Name>John</Name>
    </Person>
    <Person>
        <Friend i:nil="true"/>
        <Name>Mike</Name>
    </Person>
</ArrayOfPerson>

值得一提的是，这种方式生产的XML是不能互通的，只能用DataContractSerializer的（同样的评论被反序列化的BinaryFormatter).

.NET XML序列化 - 存储引用，而不是对象的副本

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