方式一、
XNamespace xNamespace = "http://www.sitemaps.org/schemas/sitemap/0.9";
XNamespace xhtml = "http://www.w3.org/1999/xhtml";
XElement root = new XElement(
xNamespace + "urlset",
new XAttribute("xmlns", "http://www.sitemaps.org/schemas/sitemap/0.9"),
new XAttribute(XNamespace.Xmlns + "xhtml", "http://www.w3.org/1999/xhtml"),
new XElement(
xNamespace.GetName("url"),// + "url"
new XElement(xNamespace.GetName("loc"), "http://www.example.com/english/page.html"),
new XElement(xhtml + "link",
new XAttribute("rel", "alternate"),
new XAttribute("hreflang", "de"),
new XAttribute("href", "http://www.example.com/deutsch/page.html"))
)
);
Console.WriteLine(root);
方式二、
XNamespace xNamespace = "http://www.sitemaps.org/schemas/sitemap/0.9";
XNamespace xhtml = "http://www.w3.org/1999/xhtml"; XElement root = new XElement(xNamespace + "urlset");
root.SetAttributeValue("xmlns", "http://www.sitemaps.org/schemas/sitemap/0.9");
root.SetAttributeValue(XNamespace.Xmlns + "xhtml", "http://www.w3.org/1999/xhtml"); ////创建子节点
XElement url = new XElement(xNamespace.GetName("url"));
url.SetElementValue(xNamespace.GetName("loc"), "https://translate.google.cn");
url.SetElementValue(xNamespace.GetName("lastmod"), "2018-10-22");
url.SetElementValue(xNamespace.GetName("changefreq"), "monthly");
url.SetElementValue(xNamespace.GetName("priority"), "0.9"); //xhtml:link
XElement twlink = new XElement(xhtml + "link");
twlink.SetAttributeValue("rel", "alternate");
twlink.SetAttributeValue("hreflang", "zh-tw");
twlink.SetAttributeValue("href", "https://translate.google.cn");
url.Add(twlink); XElement uslink = new XElement(xhtml + "link");
uslink.SetAttributeValue("rel", "alternate");
uslink.SetAttributeValue("hreflang", "en-tw");
uslink.SetAttributeValue("href", "https://translate.google.cn");
url.Add(uslink);
//添加节点到父节点，添加根节点到对象
root.Add(url);
Console.WriteLine(root);
控制台打印效果：（生成文件也是一样的）
<urlset xmlns="http://www.sitemaps.org/schemas/sitemap/0.9" xmlns:xhtml="http://www.w3.org/1999/xhtml">
<url>
<loc>http://www.example.com/english/page.html</loc>
<xhtml:link rel="alternate" hreflang="de" href="http://www.example.com/deutsch/page.html" />
</url>
</urlset>
-------------------------
<urlset xmlns="http://www.sitemaps.org/schemas/sitemap/0.9" xmlns:xhtml="http://www.w3.org/1999/xhtml">
<url>
<loc>https://translate.google.cn</loc>
<lastmod>--</lastmod>
<changefreq>monthly</changefreq>
<priority>0.9</priority>
<xhtml:link rel="alternate" hreflang="zh-tw" href="https://translate.google.cn" />
<xhtml:link rel="alternate" hreflang="en-tw" href="https://translate.google.cn" />
</url>
</urlset>
参考资料：
https://support.google.com/webmasters/answer/75712?hl=zh-Hant&ref_topic=4581190
https://support.google.com/webmasters/answer/189077?hl=zh-Hant&ref_topic=2370587&visit_id=636757708970115411-988286469&rd=1
https://docs.microsoft.com/en-us/dotnet/csharp/programming-guide/concepts/linq/how-to-create-a-document-with-namespaces-linq-to-xml
https://*.com/questions/34671195/how-to-format-xml-using-linq
https://*.com/questions/23223014/video-sitemap-colon-in-name-using-linq-to-xml