xdocument.toString()删除XML编码标记

要么显式写出声明,要么使用 StringWriter 并打电话 Save() :

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

class Test
{
    static void Main()
    {
        string xml = @"<?xml version='1.0' encoding='utf-8'?>
<Cooperations>
  <Cooperation />
</Cooperations>";

        XDocument doc = XDocument.Parse(xml);
        StringBuilder builder = new StringBuilder();
        using (TextWriter writer = new StringWriter(builder))
        {
            doc.Save(writer);
        }
        Console.WriteLine(builder);
    }
}

您可以很容易地将其添加为扩展方法:

public static string ToStringWithDeclaration(this XDocument doc)
{
    if (doc == null)
    {
        throw new ArgumentNullException("doc");
    }
    StringBuilder builder = new StringBuilder();
    using (TextWriter writer = new StringWriter(builder))
    {
        doc.Save(writer);
    }
    return builder.ToString();
}

这样做的好处是,如果有,它就不会爆炸。 不是 声明:)

然后您可以使用:

string x = doc.ToStringWithDeclaration();

请注意,这将使用UTF-16作为编码,因为这是 架线作家 . 你可以通过创建一个 架线作家 ,例如 to always use UTF-8 .

声明属性将包含XML声明。要获取内容加声明,可以执行以下操作:

tb_output.Text = xml.Declaration.ToString() + xml.ToString()

使用此:

output.Text = String.Concat(xml.Declaration.ToString() , xml.ToString())

我喜欢这样

        string distributorInfo = string.Empty;

        XDocument distributors = new XDocument();

     //below is important else distributors.Declaration.ToString() throws null exception
        distributors.Declaration = new XDeclaration("1.0", "utf-8", "yes"); 

        XElement rootElement = new XElement("Distributors");
        XElement distributor = null;
        XAttribute id = null;

        distributor = new XElement("Distributor");
        id = new XAttribute("Id", "12345678");
        distributor.Add(id);
        rootElement.Add(distributor);

        distributor = new XElement("Distributor");
        id = new XAttribute("Id", "22222222");

        distributor.Add(id);

        rootElement.Add(distributor);         

        distributors.Add(rootElement);

        distributorInfo = String.Concat(distributors.Declaration.ToString(), distributors.ToString());

请看下面我在DistributorInfo中得到的信息

<?xml version="1.0" encoding="utf-8" standalone="yes"?>
<Distributors>
  <Distributor Id="12345678" />
  <Distributor Id="22222222" />
  <Distributor Id="11111111" />
</Distributors>

与其他+1答案类似,但对声明有一点更详细的说明,并稍微更准确地连接起来。

<xml /> 声明应该在格式化的XML中位于它自己的行上,所以我要确保添加了换行符。 注:使用 Environment.Newline 因此,它将生成特定于平台的新行

// Parse xml declaration menthod
XDocument document1 =
  XDocument.Parse(@"<?xml version=""1.0"" encoding=""iso-8859-1""?><rss version=""2.0""></rss>");
string result1 =
  document1.Declaration.ToString() +
  Environment.NewLine +
  document1.ToString() ;

// Declare xml declaration method
XDocument document2 = 
  XDocument.Parse(@"<rss version=""2.0""></rss>");
document2.Declaration =
  new XDeclaration("1.0", "iso-8859-1", null);
string result2 =
  document2.Declaration.ToString() +
  Environment.NewLine +
  document2.ToString() ;

两种结果都会产生:

<?xml version="1.0" encoding="iso-8859-1"?>
<rss version="2.0"></rss>

也可以使用XmlWriter并调用

Writer.WriteDocType() 

方法。

其中一些答案解决了海报的要求,但似乎过于复杂。这里有一个简单的扩展方法,它可以避免需要单独的编写器,处理缺少的声明,并支持标准的ToString SaveOptions参数。

public static string ToXmlString(this XDocument xdoc, SaveOptions options = SaveOptions.None)
{
    var newLine =  (options & SaveOptions.DisableFormatting) == SaveOptions.DisableFormatting ? "" : Environment.NewLine;
    return xdoc.Declaration == null ? xdoc.ToString(options) : xdoc.Declaration + newLine + xdoc.ToString(options);
}

要使用扩展名,只需替换 xml.ToString() 具有 xml.ToXmlString()

string uploadCode = "UploadCode";
string LabName = "LabName";
XElement root = new XElement("TestLabs");
foreach (var item in returnList)
{  
       root.Add(new XElement("TestLab",
                new XElement(uploadCode, item.UploadCode),
                new XElement(LabName, item.LabName)
                            )
               );
}

XDocument returnXML = new XDocument(new XDeclaration("1.0", "UTF-8","yes"),
             root);

string returnVal;
using (var sw = new MemoryStream())
{
       using (var strw = new StreamWriter(sw, System.Text.UTF8Encoding.UTF8))
       {
              returnXML.Save(strw);
              returnVal = System.Text.UTF8Encoding.UTF8.GetString(sw.ToArray());
       }
}

// ReturnVal has the string with XML data with XML declaration tag