嵌套复合对象的 WCF XML 序列化

Question

您好，我有一个服务合同，在其实施过程中，我试图将它收到的请求参数写入一个文本文件。此处将“TypeA a”的复合对象作为参数传递。

        namespace WebService
{
    // NOTE: If you change the interface name "IRequestStatusChanged" here, you must also update the reference to "IRequestStatusChanged" in App.config.
    [ServiceContract]
    public interface IRequestStatusChanged
    {
        [OperationContract]
        Input StatusChanged(Input In);

    }

    [Serializable] [DataContract]
    public class Input
    {
        [DataMember]
        RequestStatus RS = new RequestStatus();

    }

    [Serializable] [DataContract]
    public class RequestStatus
    {
        [DataMember]
        RequestToken RT = new RequestToken();

        [DataMember]
        public String State

    }
    [Serializable] [DataContract]
    public class RequestToken
    {
        [DataMember]
        public string Id;
    }
}

Implementation of contract

namespace WebService
{
    // NOTE: If you change the class name "RequestStatusChanged" here, you must also update the reference to "RequestStatusChanged" in App.config.
    public class RequestStatusChanged : IRequestStatusChanged
    {
        public Input StatusChanged(Input In)
        {


           /* IFormatter formatter = new System.Runtime.Serialization.Formatters.Binary.BinaryFormatter();
            Stream outfile = new FileStream(@"C:\test.txt", FileMode.Open,FileAccess.Write);
            formatter.Serialize(outfile, In);
            outfile.Close(); */


            XmlSerializer serializer = new XmlSerializer(typeof(Input));
            TextWriter TW = new StreamWriter(@"c:\test.xml");
            serializer.Serialize(TW, In);
            TW.Close();

            return In;
        }

    }
}

之前我尝试 IFORMATTER 序列化对象并将其写入文本文件，但它不是人类可读的，所以我尝试了 xml 序列化。

当我检查写入的 XML 文件时，它只有“TypeA”对象的标签，而没有将“TypeB”和“TypeC”对象写入文件。我已在服务合同中将所有类标记为 [Serializable]。我想将收到的所有文本或 xml 格式的参数写入一个文件，以便它们可读（一种日志文件）。

Answer 1

XmlSerializer 仅序列化 public 成员。您定义的DataContract 类型中的所有成员都没有任何访问说明符，因此它们默认为私有。

但是，您在这里使用了两个不同的序列化框架 - DataContractSerializer 被 WCF 隐式使用，除非您另有说明，而 XmlSerializer。为什么不直接使用DataContractSerializer，因为您已经具备了 WCF 所需的所有属性？

var serialiser = new DataContractSerializer(typeof(TypeA));
serialiser.WriteObject(xmlWriter, typeAObj);

Answer 2

类型 'TypeB' 和 'TypeC' 不会写入文件，因为它们不是必需的 - 当序列化程序序列化或反序列化 TypeA 的实例时，它知道成员 'b' 的类型是TypeB，所以不写类型信息。你也需要这些信息吗？由于您正在序列化 TypeA，并且您知道字段 b 的类型为 TypeB，因此您不需要日志文件中的额外信息。

在 WCF 使用的所有序列化器中，唯一可以“强制”一直写入类型的序列化器是 JSON 序列化器 - 但是你会得到 JSON 的结果，而不是 XML - 见下文。

public class StackOverflow_6666697
{
    [DataContract]
    public class TypeA { [DataMember] public TypeB b = new TypeB(); }
    [DataContract]
    public class TypeB { [DataMember] public TypeC c = new TypeC(); }
    [DataContract]
    public class TypeC { [DataMember] public string S1; }
    public static void Test()
    {
        MemoryStream ms = new MemoryStream();
        XmlWriterSettings ws = new XmlWriterSettings
        {
            Indent = true,
            IndentChars = "  ",
            OmitXmlDeclaration = true,
            Encoding = Encoding.UTF8
        };
        TypeA instance = new TypeA { b = new TypeB { c = new TypeC { S1 = "Hello world" } } };

        XmlWriter w = XmlWriter.Create(ms, ws);
        new XmlSerializer(typeof(TypeA)).Serialize(w, instance);
        w.Flush();
        Console.WriteLine("XmlSerializer:");
        Console.WriteLine(Encoding.UTF8.GetString(ms.ToArray()));

        ms.SetLength(0);
        w = XmlWriter.Create(ms, ws);
        new DataContractSerializer(typeof(TypeA)).WriteObject(w, instance);
        w.Flush();
        Console.WriteLine("DataContractSerializer:");
        Console.WriteLine(Encoding.UTF8.GetString(ms.ToArray()));

        ms.SetLength(0);
        w = XmlWriter.Create(ms, ws);
        new NetDataContractSerializer().WriteObject(w, instance);
        w.Flush();
        Console.WriteLine("NetDataContractSerializer:");
        Console.WriteLine(Encoding.UTF8.GetString(ms.ToArray()));

        ms.SetLength(0);
        w = JsonReaderWriterFactory.CreateJsonWriter(ms, Encoding.UTF8);
        new DataContractJsonSerializer(typeof(TypeA), null, 65536, false, null, true).WriteObject(w, instance);
        w.Flush();
        Console.WriteLine("DataContractJsonSerializer:");
        Console.WriteLine(Encoding.UTF8.GetString(ms.ToArray()));
    }
}

另一种选择（我真的不建议这样做，因为您会为了记录而更改系统的逻辑）是将字段声明为object。这样，由于声明的类型与实际类型不同，类型信息将被写出 - 见下文。

public class StackOverflow_6666697
{
    [DataContract]
    public class TypeA { [DataMember] public object b = new TypeB(); }
    [DataContract]
    public class TypeB { [DataMember] public object c = new TypeC(); }
    [DataContract]
    public class TypeC { [DataMember] public string S1; }
    public static void Test()
    {
        MemoryStream ms = new MemoryStream();
        XmlWriterSettings ws = new XmlWriterSettings
        {
            Indent = true,
            IndentChars = "  ",
            OmitXmlDeclaration = true,
            Encoding = Encoding.UTF8
        };
        TypeA instance = new TypeA { b = new TypeB { c = new TypeC { S1 = "Hello world" } } };

        XmlWriter w = XmlWriter.Create(ms, ws);
        new XmlSerializer(typeof(TypeA), new Type[] { typeof(TypeB), typeof(TypeC) }).Serialize(w, instance);
        w.Flush();
        Console.WriteLine("XmlSerializer:");
        Console.WriteLine(Encoding.UTF8.GetString(ms.ToArray()));

        ms.SetLength(0);
        w = XmlWriter.Create(ms, ws);
        new DataContractSerializer(typeof(TypeA), new Type[] { typeof(TypeB), typeof(TypeC) }).WriteObject(w, instance);
        w.Flush();
        Console.WriteLine("DataContractSerializer:");
        Console.WriteLine(Encoding.UTF8.GetString(ms.ToArray()));

        ms.SetLength(0);
        w = XmlWriter.Create(ms, ws);
        new NetDataContractSerializer().WriteObject(w, instance);
        w.Flush();
        Console.WriteLine("NetDataContractSerializer:");
        Console.WriteLine(Encoding.UTF8.GetString(ms.ToArray()));

        ms.SetLength(0);
        w = JsonReaderWriterFactory.CreateJsonWriter(ms, Encoding.UTF8);
        new DataContractJsonSerializer(typeof(TypeA), new Type[] { typeof(TypeB), typeof(TypeC) }, 65536, false, null, true).WriteObject(w, instance);
        w.Flush();
        Console.WriteLine("DataContractJsonSerializer:");
        Console.WriteLine(Encoding.UTF8.GetString(ms.ToArray()));
    }
}