使用XmlSerializer反序列化List <int>导致额外的项目

Question

我注意到XmlSerializer和通用列表(特别是List<int>)的奇怪行为.我想知道是否有人以前见过这个或知道发生了什么.看起来好像序列化工作正常但反序列化想要在列表中添加额外的项目.下面的代码演示了这个问题.

可序列化类:

public class ListTest
{
    public int[] Array { get; set; }
    public List<int> List { get; set; }

    public ListTest()
    {
        Array = new[] {1, 2, 3, 4};
        List = new List<int>(Array);
    }
}

测试代码:

ListTest listTest = new ListTest();
Debug.WriteLine("Initial Array: {0}", (object)String.Join(", ", listTest.Array));
Debug.WriteLine("Initial List: {0}", (object)String.Join(", ", listTest.List));

XmlSerializer serializer = new XmlSerializer(typeof(ListTest));
StringBuilder xml = new StringBuilder();
using(TextWriter writer = new StringWriter(xml))
{
    serializer.Serialize(writer, listTest);
}

Debug.WriteLine("XML: {0}", (object)xml.ToString());

using(TextReader reader = new StringReader(xml.ToString()))
{
    listTest = (ListTest) serializer.Deserialize(reader);
}

Debug.WriteLine("Deserialized Array: {0}", (object)String.Join(", ", listTest.Array));
Debug.WriteLine("Deserialized List: {0}", (object)String.Join(", ", listTest.List));

调试输出:

Initial Array: 1, 2, 3, 4
Initial List: 1, 2, 3, 4

XML:

<?xml version="1.0" encoding="utf-16"?>
<ListTest xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xmlns:xsd="http://www.w3.org/2001/XMLSchema">
  <Array>
    <int>1</int>
    <int>2</int>
    <int>3</int>
    <int>4</int>
  </Array>
  <List>
    <int>1</int>
    <int>2</int>
    <int>3</int>
    <int>4</int>
  </List>
</ListTest>

Deserialized Array: 1, 2, 3, 4
Deserialized List: 1, 2, 3, 4, 1, 2, 3, 4

请注意,数组和列表似乎都已正确序列化为XML,但在反序列化时,数组出现正确,但列表返回时带有一组重复的项.有任何想法吗？

Answer 1

这是因为您正在构造函数中初始化List.当您进行反序列化时,会创建一个新的ListTest,然后从状态填充该对象.

想想这样的工作流程

1. 创建一个新的ListTest
2. 执行构造函数(添加1,2,3,4)
3. 反序列化xml状态,并将1,2,3,4添加到List

一个简单的解决方案是在构造函数范围之外初始化对象.

public class ListTest
{
    public int[] Array { get; set; }
    public List<int> List { get; set; }

    public ListTest()
    {

    }

    public void Init() 
    {
        Array = new[] { 1, 2, 3, 4 };
        List = new List<int>(Array);
    }
}

ListTest listTest = new ListTest();
listTest.Init(); //manually call this to do the initial seed