Question

我正在尝试生成这样的XML：

<?xml version="1.0"?>
<!DOCTYPE APIRequest SYSTEM
"https://url">
<APIRequest>
  <Head>
      <Key>123</Key>
  </Head>
  <ObjectClass>
    <Field>Value</Field
  </ObjectClass>
</APIRequest>

我有一个用XMLSerialization属性装饰的类（ObjectClass），如下所示：

[XmlRoot("ObjectClass")]
public class ObjectClass
{
    [XmlElement("Field")]
    public string Field { get; set; }
}

我的真正hacky直觉思想让我的工作就是在序列化时这样做：

ObjectClass inst = new ObjectClass();
XmlSerializer serializer = new XmlSerializer(inst.GetType(), "");

StringWriter w = new StringWriter();
w.WriteLine(@"<?xml version=""1.0""?>");
w.WriteLine("<!DOCTYPE APIRequest SYSTEM");
w.WriteLine(@"""https://url"">");
w.WriteLine("<APIRequest>");
w.WriteLine("<Head>");
w.WriteLine(@"<Field>Value</Field>");
w.WriteLine(@"</Head>");

XmlSerializerNamespaces ns = new XmlSerializerNamespaces();
ns.Add("", ""); 
serializer.Serialize(w, inst, ns);

w.WriteLine("</APIRequest>");

但是，这会生成如下XML：

<?xml version="1.0"?>
<!DOCTYPE APIRequest SYSTEM
"https://url">
<APIRequest>
  <Head>
      <Key>123</Key>
  </Head>
  <?xml version="1.0" encoding="utf-16"?>
  <ObjectClass>
    <Field>Value</Field>
  </ObjectClass>
</APIRequest>

即。 serialize语句自动添加＆lt;？xml文本声明。

我知道我正在攻击这个错误，所以有人能指出我正确的方向吗？

作为一个注释，我认为只使用一个带有ObjectClass的APIRequest类来实现它是否具有实际意义（因为有20种不同类型的ObjectClass，它们每个都需要这个样板）但是如果我错了。

Answer 1

试试这个：

internal static string ToXml(object obj)
{
  string retval = null;
  if (obj != null)
  {
    StringBuilder sb = new StringBuilder();
    using(XmlWriter writer = XmlWriter.Create(sb, new XmlWriterSettings() { OmitXmlDeclaration = true }))
    {
      new XmlSerializer(obj.GetType()).Serialize(writer, obj);
    }
    retval = sb.ToString();
  }
  return retval;
}

Answer 2

永远不要使用字符串连接来构建xml。这是邪恶的。

输出：

<?xml version="1.0" encoding="utf-16"?>
<!DOCTYPE APIRequest SYSTEM "https://url">
<APIRequest>
  <Head>
    <Key>123</Key>
  </Head>
  <ObjectClass>
    <Field>Value</Field>
  </ObjectClass>
</APIRequest>

代码：

using System;
using System.Diagnostics;
using System.Text;
using System.Xml;
using System.Xml.Serialization;

public static class Program {
    public static void Main() {
        var obj = new ObjectClass { Field = "Value" };

        var settings = new XmlWriterSettings {
            Indent = true
        };

        var xml = new StringBuilder();
        using (var writer = XmlWriter.Create(xml, settings)) {
            Debug.Assert(writer != null);

            writer.WriteDocType("APIRequest", null, "https://url", null);
            writer.WriteStartElement("APIRequest");
            writer.WriteStartElement("Head");
            writer.WriteElementString("Key", "123");
            writer.WriteEndElement(); // </Head>

            var nsSerializer = new XmlSerializerNamespaces();
            nsSerializer.Add("", "");

            var xmlSerializer = new XmlSerializer(obj.GetType(), "");
            xmlSerializer.Serialize(writer, obj, nsSerializer);

            writer.WriteEndElement(); // </APIRequest>
        }

        Console.WriteLine(xml.ToString());
        Console.ReadLine();
    }
}

[XmlRoot("ObjectClass")]
public class ObjectClass {
    [XmlElement("Field")]
    public string Field { get; set; }
}

Answer 3

如果出于性能原因不想依赖xml编写器等，可以这样做：

// Read into memory stream and set namespaces to empty strings
XmlSerializerNamespaces nsSerializer = new XmlSerializerNamespaces();
nsSerializer.Add(string.Empty, string.Empty);
XmlSerializer xs = new XmlSerializer(typeof(Model.AudioItem));
xs.Serialize(ms, item, nsSerializer);

// Read into UTF-8 stream and read off first line (i.e "<?xml version="1.0"?>")
StreamReader sr = new StreamReader(ms);
ms.Position = 0;
sr.ReadLine();

sr.ReadToEnd（）。ToString（）现在包含裸序列化

Answer 4

派生您自己的XmlTextWriter以省略XML声明。

Private Class MyXmlTextWriter
Inherits XmlTextWriter
Sub New(ByVal sb As StringBuilder)
    MyBase.New(New StringWriter(sb))
End Sub
Sub New(ByVal w As TextWriter)
    MyBase.New(w)
End Sub

Public Overrides Sub WriteStartDocument()
    ' Don't emit XML declaration
End Sub
Public Overrides Sub WriteStartDocument(ByVal standalone As Boolean)
    ' Don't emit XML declaration
End Sub
End Class

使用派生的MyXmlTextWriter的实例调用Serialize。

Dim tw As New MyXmlTextWriter(sb)
Dim objXmlSerializer As New XmlSerializer(type)
objXmlSerializer.Serialize(tw, obj)

Answer 5

Scott Hanselman's在此发表了一篇好文章。我使用了Kzu的例子（斯科特的博客指向的）一段时间以后也做了同样的事情并且效果很好。

Answer 6

if (!string.IsNullOrEmpty(strXML) && strXML.Contains(@"<?xml"))
strXML = strXML.Remove(0, strXML.IndexOf(@"?>", 0) + 2);

Answer 7

一条衬里，用于从字符串中删除第一行：

String.Join("\n", strXML.Split('\n').Skip(1).ToArray())

不优雅，但简洁。

没有<！ - ？xml - >文本声明的.NET XML序列化

7 个答案: