保存XmlDocument时,它忽略XmlDeclaration(UTF8)中的编码并使用UTF16

Question

我有以下代码:

var doc = new XmlDocument();

XmlDeclaration xmlDeclaration = doc.CreateXmlDeclaration("1.0", "UTF-8", null);
doc.AppendChild(xmlDeclaration);

XmlElement root = doc.CreateElement("myRoot");
doc.AppendChild(root);
root.InnerText = "myInnerText";

StringWriter sw = new StringWriter();
doc.Save(sw);
Console.WriteLine(sw.ToString());

Console.WriteLine();

MemoryStream ms = new MemoryStream();
doc.Save(ms);
Console.WriteLine(Encoding.ASCII.GetString(ms.ToArray()));

这是输出:

<?xml version="1.0" encoding="utf-16"?>
<myRoot>myInnerText</myRoot>

???<?xml version="1.0" encoding="UTF-8"?>
<myRoot>myInnerText</myRoot>

基本上它的作用是创建一个xml文件,并将编码设置为utf8,但是当它将它保存到字符串编写器时,它会忽略我的编码并使用utf16.但是,在使用内存流时,它使用utf8(带有额外的BOM表字符)

为什么是这样？为什么不尊重我对utf-8的显式编码设置？

非常感谢

Answer 1

因为您所做的只是设置一个表示它是UTF-8的XML元素,所以您实际上并没有将其保存为UTF-8.您需要将输出流设置为使用UTF-8,如下所示:

var doc = new XmlDocument();
XmlElement root = doc.CreateElement("myRoot");
doc.AppendChild(root);
root.InnerText = "myInnerText";
using(TextWriter sw = new StreamWriter("C:\\output.txt", false, Encoding.UTF8)) //Set encoding
{
    doc.Save(sw);
}

一旦这样做,您甚至不必添加XML声明.它自己解决了这个问题.如果要将其保存到MemoryStream,请使用包装MemoryStream的StreamWriter.

Answer 2

我使用以下方法，它写得很漂亮，并且是 UTF-8

public static string Beautify(XmlDocument doc)
{
    string xmlString = null;
    using (MemoryStream ms = new MemoryStream()) {
        XmlWriterSettings settings = new XmlWriterSettings {
            Encoding = new UTF8Encoding(false),
            Indent = true,
            IndentChars = "  ",
            NewLineChars = "\r\n",
            NewLineHandling = NewLineHandling.Replace
        };
        using (XmlWriter writer = XmlWriter.Create(ms, settings)) {
            doc.Save(writer);
        }
        xmlString = Encoding.UTF8.GetString(ms.ToArray());
    }
    return xmlString;
}

像这样称呼它：

File.WriteAllText(fileName, Utilities.Beautify(xmlDocument));