c#操作xml的问题 急！ 高手指教 - .NET技术 / C#

先上代码
 public override string SerializeToXml(object objArg)
  {
  if (objArg == null)
  return "";

  StringBuilder builder = new StringBuilder();
  try
  {
  //声明Xmldocument对象
  _docXml = new XmlDocument();

  //处理描述信息
  _docXml.AppendChild(_docXml.CreateXmlDeclaration("1.0", "utf-8", "yes"));

  //序列化对象
  DoSirialAtFirst(objArg, _docXml);

  //写入到Builder对象
  XmlWriter writer = XmlWriter.Create(builder); 

  //保存
  _docXml.Save(writer);
  }
  catch (Exception ex)
  {
  throw new Exception("客户端序列化对象出错！",ex);
  }
  return builder.ToString();
  }
红色区域设置怎么无效啊，还有msdn上面说如果不进行encoding的设置，默认utf-8，为什么我设置不设置都是utf-16郁闷，因为要和java交互，所以必须用utf-8，汗~

---

学习...

---

XmlDocument.InsertBefore();

XmlDocument xmldoc =new ...
XmlDeclicration dec = xmldoc.CreateXmlDeclaration