在 XmlWriter 中省略 XmlDeclaration 并实现 IXmlSerializable

Question

我想通过实现 IXmlSerialized 创建自定义 xml 序列化。 我有一个实现 IXmlSerialized 接口的测试类：

[Serializable]
public class Employee : IXmlSerializable
{
    public Employee()
    {
        Name = "Vyacheslav";

        Age = 23;                 
    }

    public string Name{get; set;}

    public int Age { get; set; }



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

    public void ReadXml(XmlReader reader)
    {
        this.Name = reader["Name"].ToString();
        this.Age = Int32.Parse(reader["Age"].ToString());
    }

    public void WriteXml(XmlWriter writer)
    {
        XmlWriterSettings settings = new XmlWriterSettings();
        settings.OmitXmlDeclaration = true;
        settings.ConformanceLevel = ConformanceLevel.Fragment;

        XmlWriter newWriter = XmlWriter.Create(writer, settings);
        newWriter.WriteAttributeString("Name", this.Name);
        newWriter.WriteAttributeString("Age", this.Age.ToString());            
    }
}

我想要做的是省略 xml 声明。为此，我创建了 XmlWriterSettings 的正确实例并将其作为第二个参数传递以创建新的 XmlWriter。 但是当我调试这段代码时，我看到 newWriter.Settings.OmitXmlDeclaration 设置为 false 并且序列化数据包含标记。我做错了什么？

实际的序列化如下所示：

        var me = new Employee();

        XmlSerializer serializer = new XmlSerializer(typeof(Employee));
        TextWriter writer = new StreamWriter(@"D:\file.txt");
        serializer.Serialize(writer, me);
        writer.Close();

第二个问题是 - 如果我想序列化在要序列化的字段中具有自定义类型 ContactInfo 的 Employee 类型，我是否也需要在 ContactInfo 上实现 IXmlSerialized ？

Answer 1

writer-settings 是最外层 writer 的函数；您应该将其应用到创建文件的代码中，即

using(var file = File.Create("file.txt"))
using(var writer = XmlWriter.Create(file, settings))
{
    serializer.Serialize(writer, me);
}

另外，您不需要来实现IXmlSerialized。你无法在内在层面做到这一点——已经太晚了。

例如：

using System.IO;
using System.Xml;
using System.Xml.Serialization;
public class Employee 
{
    [XmlAttribute] public string Name { get; set; }
    [XmlAttribute] public int Age { get; set; }
}
class Program
{
    static void Main()
    {
        var settings = new XmlWriterSettings();
        settings.OmitXmlDeclaration = true;
        var me = new Employee {
            Name = "Vyacheslav", Age = 23
        };
        var serializer = new XmlSerializer(typeof (Employee));
        using (var file = File.Create("file.txt"))
        using (var writer = XmlWriter.Create(file, settings))
        {
            serializer.Serialize(writer, me);
        }
    }
}

如果您不需要额外的命名空间，那么：

        var ns = new XmlSerializerNamespaces();
        ns.Add("", "");
        serializer.Serialize(writer, me, ns);

它将生成文件：

<Employee Name="Vyacheslav" Age="23" />