Question

我在C＃中有这个课程

public class ExerciseDTO {
    Dictionary<String, String> qa;
    private String materialId, content, topic;

    //constructors

    //properties

    public void makePersistent(String path) {
        Stream outputStream = File.OpenWrite(path + @"\" + this.topic + ".xml");
        XmlSerializer serializer = new XmlSerializer(typeof(ExerciseDTO));
        serializer.Serialize(outputStream, this);
        outputStream.Flush();
        outputStream.Close();
    }
}

调用makePersistent方法会使应用程序抛出带有消息An error occured while reflecting object of type ExerciseDTO的异常。为什么我不能序列化这个类的实例？

Answer 1

为什么我不能序列化这个类的实例？

因为XmlSerializer类doesn't support serializing Dictionary<TKey, TValue>属性。

作为替代方案，您可以使用支持词典的DataContractSerializer。

Answer 2

[Serializable]
public class ExerciseDTO {
...
}

您还应该有一个默认（免费参数）构造函数
如果您想要自动序列化，您还应该公开您的财产
字典的序列化＆lt;＆gt; .net不支持，但有工作区，例如this post。

编辑：如下所示：它应该是 XmlSerializer 类不支持“字典序列化＆lt;＆gt;”。

Answer 3

Darin说，Dictionary不是XML可序列化的。您可以创建自己的XmlSerializableDictionary。网上有很多很好的例子。这是一个：

http://weblogs.asp.net/pwelter34/archive/2006/05/03/444961.aspx

如果链接将来死亡，请复制/粘贴：

using System;
using System.Collections.Generic;
using System.Text;
using System.Xml.Serialization;

[XmlRoot("dictionary")]
public class SerializableDictionary<TKey, TValue>
    : Dictionary<TKey, TValue>, IXmlSerializable
{
    #region IXmlSerializable Members

    public System.Xml.Schema.XmlSchema GetSchema()
    {
        return null;
    }

    public void ReadXml(System.Xml.XmlReader reader)
    {
        XmlSerializer keySerializer = new XmlSerializer(typeof(TKey));
        XmlSerializer valueSerializer = new XmlSerializer(typeof(TValue));
        bool wasEmpty = reader.IsEmptyElement;

        reader.Read();

        if (wasEmpty)
            return;

        while (reader.NodeType != System.Xml.XmlNodeType.EndElement)
        {
            reader.ReadStartElement("item");
            reader.ReadStartElement("key");

            TKey key = (TKey)keySerializer.Deserialize(reader);

            reader.ReadEndElement();
            reader.ReadStartElement("value");

            TValue value = (TValue)valueSerializer.Deserialize(reader);
            reader.ReadEndElement();
            this.Add(key, value);
            reader.ReadEndElement();
            reader.MoveToContent();
        }

        reader.ReadEndElement();
    } 

    public void WriteXml(System.Xml.XmlWriter writer)
    {
        XmlSerializer keySerializer = new XmlSerializer(typeof(TKey));

        XmlSerializer valueSerializer = new XmlSerializer(typeof(TValue));

        foreach (TKey key in this.Keys)
        {
            writer.WriteStartElement("item");

            writer.WriteStartElement("key");
            keySerializer.Serialize(writer, key);
            writer.WriteEndElement();
            writer.WriteStartElement("value");
            TValue value = this[key];
            valueSerializer.Serialize(writer, value);
            writer.WriteEndElement();
            writer.WriteEndElement();
        }
    }
    #endregion
}

序列化对象的问题

3 个答案: