Force XDocument to write to String with UTF-8 enco

问题:

I want to be able to write XML to a String with the declaration and with UTF-8 encoding. This seems mighty tricky to accomplish.

I have read around a bit and tried some of the popular answers for this but the they all have issues. My current code correctly outputs as UTF-8 but does not maintain the original formatting of the XDocument (i.e. indents / whitespace)!

Can anyone offer some advice please?

XDocument xml = new XDocument(new XDeclaration("1.0", "utf-8", "yes"), xelementXML);

MemoryStream ms = new MemoryStream();
using (XmlWriter xw = new XmlTextWriter(ms, Encoding.UTF8))
{
    xml.Save(xw);
    xw.Flush();

    StreamReader sr = new StreamReader(ms);
    ms.Seek(0, SeekOrigin.Begin);

    String xmlString = sr.ReadToEnd();
}

The XML requires the formatting to be identical to the way .ToString() would format it i.e.

<?xml version="1.0" encoding="utf-8" standalone="yes"?>
<root>
    <node>blah</node>
</root>

What I'm currently seeing is

<?xml version="1.0" encoding="utf-8" standalone="yes"?><root><node>blah</node></root>

Update I have managed to get this to work by adding XmlTextWriter settings... It seems VERY clunky though!

MemoryStream ms = new MemoryStream();
XmlWriterSettings settings = new XmlWriterSettings();
settings.Encoding = Encoding.UTF8;
settings.ConformanceLevel = ConformanceLevel.Document;
settings.Indent = true;
using (XmlWriter xw = XmlTextWriter.Create(ms, settings))
{
    xml.Save(xw);
    xw.Flush();

    StreamReader sr = new StreamReader(ms);
    ms.Seek(0, SeekOrigin.Begin);
    String blah = sr.ReadToEnd();
}

回答1:

Try this:

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

class Test
{
    static void Main()
    {
        XDocument doc = XDocument.Load("test.xml",
                                       LoadOptions.PreserveWhitespace);
        doc.Declaration = new XDeclaration("1.0", "utf-8", null);
        StringWriter writer = new Utf8StringWriter();
        doc.Save(writer, SaveOptions.None);
        Console.WriteLine(writer);
    }

    private class Utf8StringWriter : StringWriter
    {
        public override Encoding Encoding { get { return Encoding.UTF8; } }
    }
}

Of course, you haven't shown us how you're building the document, which makes it hard to test... I've just tried with a hand-constructed XDocument and that contains the relevant whitespace too.

回答2:

Try XmlWriterSettings:

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

And pass it on like

using (XmlWriter xw = XmlWriter.Create(sb, xws))

回答3:

See also https://stackoverflow.com/a/3288376/1430535

return xdoc.Declaration.ToString() + Environment.NewLine + xdoc.ToString();