下面的程序是我在 C# 中反序列化 XML 时发现的问题的人为示例。我有两个单独的程序集，它们声明了一个具有相同名称的类型，在下面的示例中为“Country”。这些类型由 XML namespace 区分。当我反序列化包含单个“国家/地区”元素的配置文件时，将解析正确的“国家/地区”类型。但是，如果我反序列化“国家”元素的“列表”，则会反序列化错误的“国家”类型。
class Program
{
static void Main(string[] args)
{
XDocument gbConfig = XDocument.Parse(@"<TradingBlocConfiguration>
<GreatBritain>
<Country/>
<Countries>
<Country/>
<Country/>
</Countries>
</GreatBritain> </TradingBlocConfiguration>");
XDocument euConfig = XDocument.Parse(@"<TradingBlocConfiguration>
<EuropeanUnion>
<Country/>
<Countries>
<Country/>
<Country/>
</Countries>
</EuropeanUnion> </TradingBlocConfiguration>");
var greatBritainConfiguration = BuildConfig<TradingBlocConfiguration>(gbConfig);
// A single 'Country' is always deserialized correctly..
Console.WriteLine("Great Britain Country Type " + greatBritainConfiguration.TradingBlocConfig.MemberCountry.GetType());
// A List of 'Country' is deserialized to the wrong type, depending on what '[XmlElement]' tag is listed first.
Console.WriteLine("Great Britain Countries Type " + greatBritainConfiguration.TradingBlocConfig.MemberCountries[0].GetType());
var euConfiguration = BuildConfig<TradingBlocConfiguration>(euConfig);
Console.WriteLine("EU Country Type " + euConfiguration.TradingBlocConfig.MemberCountry.GetType());
Console.WriteLine("EU Countries Type " + euConfiguration.TradingBlocConfig.MemberCountries[0].GetType());
Console.ReadLine();
}
private static T BuildConfig<T>(XDocument doc) where T : class
{
var stream = new MemoryStream();
doc.Save(stream);
T result;
using (var reader = new StreamReader(stream))
{
stream.Position = 0;
var xs = new XmlSerializer(typeof(T));
result = (T)xs.Deserialize(reader);
}
return result;
}
}
[XmlRoot("TradingBlocConfiguration")]
public sealed class TradingBlocConfiguration
{
[XmlElement("GreatBritain", typeof(GB.GreatBritain))]
[XmlElement("EuropeanUnion", typeof(EU.EuropeanUnion))]
public TradingBloc TradingBlocConfig { get; set; }
}
[XmlRoot]
[XmlInclude(typeof(GB.GreatBritain))]
[XmlInclude(typeof(EU.EuropeanUnion))]
public class BaseCountry { }
public abstract class TradingBloc
{
[XmlIgnore]
public abstract List<BaseCountry> MemberCountries { get; set; }
[XmlIgnore]
public abstract BaseCountry MemberCountry { get; set; }
}
namespace GB
{
[XmlRoot("GreatBritain")]
public class GreatBritain : TradingBloc
{
[XmlElement("Country", typeof(Country))]
public override BaseCountry MemberCountry { get; set; }
[XmlArray("Countries")]
[XmlArrayItem("Country", typeof(Country))]
public override List<BaseCountry> MemberCountries { get; set; }
[XmlRoot(Namespace = "GB")]
public class Country : BaseCountry { }
}
}
namespace EU
{
[XmlRoot("EuropeanUnion")]
public class EuropeanUnion : TradingBloc
{
[XmlElement("Country", typeof(Country))]
public override BaseCountry MemberCountry { get; set; }
[XmlArray("Countries")]
[XmlArrayItem("Country", typeof(Country))]
public override List<BaseCountry> MemberCountries { get; set; }
[XmlRoot(Namespace = "EU")]
public class Country : BaseCountry { }
}
}
如果你运行上面的例子，输出是:
Great Britain Country Type XmlSerializationTests.GB.GreatBritain+Country
Great Britain Countries Type XmlSerializationTests.EU.EuropeanUnion+Country
EU Country Type XmlSerializationTests.EU.EuropeanUnion+Country
EU Countries Type XmlSerializationTests.EU.EuropeanUnion+Country
“英国国家/地区类型”不正确。如果您更改 TradingBlocConfiguration 类中 [XmlElement] 属性的顺序，例如:
[XmlRoot("TradingBlocConfiguration")]
public sealed class TradingBlocConfiguration
{
[XmlElement("EuropeanUnion", typeof(EU.EuropeanUnion))]
[XmlElement("GreatBritain", typeof(GB.GreatBritain))]
public TradingBloc TradingBlocConfig { get; set; }
}
然后结果变为:
Great Britain Country Type XmlSerializationTests.GB.GreatBritain+Country
Great Britain Countries Type XmlSerializationTests.GB.GreatBritain+Country
EU Country Type XmlSerializationTests.EU.EuropeanUnion+Country
EU Countries Type XmlSerializationTests.GB.GreatBritain+Country
在这种情况下，英国看起来不错，但欧盟是错误的 :)。谁能解释为什么 List 被反序列化为错误的类型？
最佳答案
解决方案是添加 xmlns 标签。下面更新的代码可以正常工作:
class Program
{
static void Main(string[] args)
{
XDocument gbConfig = XDocument.Parse(@"<TradingBlocConfiguration>
<GreatBritain xmlns=""GB"">
<Country/>
<Countries>
<Country/>
<Country/>
</Countries>
</GreatBritain> </TradingBlocConfiguration>");
XDocument euConfig = XDocument.Parse(@"<TradingBlocConfiguration>
<EuropeanUnion xmlns=""EU"">
<Country/>
<Countries>
<Country/>
<Country/>
</Countries>
</EuropeanUnion> </TradingBlocConfiguration>");
var greatBritainConfiguration = BuildConfig<TradingBlocConfiguration>(gbConfig);
// A single 'Country' is always deserialized correctly..
Console.WriteLine("Great Britain Country Type " + greatBritainConfiguration.TradingBlocConfig.MemberCountry.GetType());
// A List of 'Country' is deserialized to the wrong type, depending on what '[XmlElement]' tag is listed first.
Console.WriteLine("Great Britain Countries Type " + greatBritainConfiguration.TradingBlocConfig.MemberCountries[0].GetType());
var euConfiguration = BuildConfig<TradingBlocConfiguration>(euConfig);
Console.WriteLine("EU Country Type " + euConfiguration.TradingBlocConfig.MemberCountry.GetType());
Console.WriteLine("EU Countries Type " + euConfiguration.TradingBlocConfig.MemberCountries[0].GetType());
Console.ReadLine();
}
private static T BuildConfig<T>(XDocument doc) where T : class
{
var stream = new MemoryStream();
doc.Save(stream);
T result;
using (var reader = new StreamReader(stream))
{
stream.Position = 0;
var xs = new XmlSerializer(typeof(T), new Type[] { typeof(GB.GreatBritain.Country) });
result = (T)xs.Deserialize(reader);
}
return result;
}
}
[XmlRoot("TradingBlocConfiguration")]
public sealed class TradingBlocConfiguration
{
[XmlElement("GreatBritain", typeof(GB.GreatBritain), Namespace = "GB")]
[XmlElement("EuropeanUnion", typeof(EU.EuropeanUnion), Namespace = "EU")]
public TradingBloc TradingBlocConfig { get; set; }
}
[XmlRoot]
[XmlInclude(typeof(GB.GreatBritain))]
[XmlInclude(typeof(EU.EuropeanUnion))]
public class BaseCountry { }
public abstract class TradingBloc
{
[XmlIgnore]
public abstract List<BaseCountry> MemberCountries { get; set; }
[XmlIgnore]
public abstract BaseCountry MemberCountry { get; set; }
}
namespace GB
{
[XmlRoot("GreatBritain")]
public class GreatBritain : TradingBloc
{
[XmlElement("Country", typeof(Country))]
public override BaseCountry MemberCountry { get; set; }
[XmlArray("Countries")]
[XmlArrayItem("Country", typeof(Country))]
public override List<BaseCountry> MemberCountries { get; set; }
[XmlRoot(Namespace = "GB")]
public class Country : BaseCountry { }
}
}
namespace EU
{
[XmlRoot("EuropeanUnion")]
public class EuropeanUnion : TradingBloc
{
[XmlElement("Country", typeof(Country))]
public override BaseCountry MemberCountry { get; set; }
[XmlArray("Countries")]
[XmlArrayItem("Country", typeof(Country))]
public override List<BaseCountry> MemberCountries { get; set; }
[XmlRoot(Namespace = "EU")]
public class Country : BaseCountry { }
}
}
关于C# XMLSerializer 将错误的类型反序列化为列表，我们在Stack Overflow上找到一个类似的问题： https://stackoverflow.com/questions/43088469/
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