为什么我的XDocument在我不想要时保存声明？

Question

我有以下代码:

class Program
{
    static void Main(string[] args)
    {
        using (var stream = File.Create(@"C:\test.xml"))
        {
            var xml =
                new XElement("root",
                    new XElement("subelement1", "1"),
                    new XElement("subelement2", "2"));

            var doc = new XDocument(xml);
            doc.Declaration = null;
            doc.Save(stream);
        }
    }
}

我试图在没有xml声明的情况下保存XML,但即使我将声明归零XDocument,它仍然被保存到最终的XML中.

此代码输出:

<?xml version="1.0" encoding="utf-8"?>
<root>
  <subelement1>1</subelement1>
  <subelement2>2</subelement2>
</root>

Answer 1

相反,XDocument.Save()您可以使用XmlWriter与XmlWriterSettings.OmitXmlDeclaration设置为true

using System.IO;
using System.Xml;
using System.Xml.Linq;

XmlWriterSettings xws = new XmlWriterSettings();
xws.OmitXmlDeclaration = true;
xws.Indent = true;

using (var stream = File.Create(@"C:\test.xml"))
using (XmlWriter xw = XmlWriter.Create(stream, xws))
{
    var xml = new XElement(
        "root",
        new XElement("subelement1", "1"),
        new XElement("subelement2", "2"));

    xml.Save(xw);
}

Answer 2

您可以使用XmlWriter自定义XmlWriterSettings(您需要使用using指令System.Xml)来执行此操作:

using System;
using System.IO;
using System.Xml;
using System.Xml.Linq;

class Program
{
    static void Main(string[] args)
    {
        var xml =
            new XElement("root",
                         new XElement("subelement1", "1"),
                         new XElement("subelement2", "2"));

        var doc = new XDocument(xml);
        var settings = new XmlWriterSettings
        {
            OmitXmlDeclaration = true
        };
        using (var stream = File.Create(@"test.xml"))
        {
            using (var writer = XmlWriter.Create(stream, settings))
            {
                doc.Save(writer);
            }
        }
    }
}

这是假设您要指定Stream- 您还可以XmlWriter从文件名创建:

using (var writer = XmlWriter.Create("test.xml", settings))
{
    doc.Save(writer);
}

(如果你不需要XDocument其他任何东西,你可以Save以同样的方式调用根元素.)