"此XmlReader不支持ReadElementContentAsBase64方法"

Question

using System.IO;
using System.Runtime.Serialization;
using System.Xml;
using System.Xml.Schema;
using System.Xml.Serialization;

namespace XmlTest
{
    class TestClass : IXmlSerializable
    {
        public XmlSchema GetSchema()
        {
            return null;
        }

        public void ReadXml(XmlReader reader)
        {
            var data = new byte[3];
            reader.ReadStartElement();
            reader.ReadElementContentAsBase64(data, 0, data.Length);
        }

        public void WriteXml(XmlWriter writer)
        {
            var data = new byte[] { 1, 2, 3 };
            writer.WriteBase64(data, 0, data.Length);
        }

        public static void Main()
        {
            var serializer = new DataContractSerializer(typeof(TestClass));

            var stringWriter = new StringWriter();
            using (var writer = XmlWriter.Create(stringWriter))
            {
                serializer.WriteObject(writer, new TestClass());
            }

            var stringReader = new StringReader(stringWriter.ToString());
            using (var reader = XmlReader.Create(stringReader))
            {
                serializer.ReadObject(reader, true);
            }
        }
    }
}

该ReadElementContentAsBase64行抛出NotSupportedException消息:

此XmlReader不支持ReadElementContentAsBase64方法.使用CanReadBinaryContent属性来查明读者是否实现了它.

(我查了一下,CanReadBinaryContent返回true)

我正在使用Microsoft .NET 3.5框架实现.

有什么可能导致这种情况？

注意:我有意将DataContractSerializer与IXmlSerializable混合使用.我意识到DataContractSerializer更常见的方法是让我的类成为[DataContract].

编辑:我现在正在使用一种解决方法:
Convert.FromBase64String(reader.ReadElementContentAsString())
仍然,我想知道为什么常规方式失败.

Answer 1

我也遇到过这个问题.linq创建的XmlReader doc.CreateReader()没有实现Base64解码.我首先保存到MemoryStream并从中创建一个XmlReader:

     Stream s = new MemoryStream();
     XmlSerializer serializer = new XmlSerializer(typeof(SerializableDocument));   
     document.Save(s);
     s.Seek(0, SeekOrigin.Begin);

     using (XmlReader newReader = XmlReader.Create(s))
     {
        SerializableDocument serializableDocument = (SerializableDocument)serializer.Deserialize(newReader);
        // do stuff with it
     }

Answer 2

我接受了罗伯特的答案并将其变成了扩展方法，享受吧！

public static T DeserializeWithBinaryData<T>(this XElement el)
{
    var xDoc = el.ToXmlDocument();
    using (var ms = new MemoryStream())
    {
        xDoc.Save(ms);
        ms.Seek(0, SeekOrigin.Begin);
        var serializer = new XmlSerializer(typeof (T));
        return (T)serializer.Deserialize(ms);
    }
}