通过文件流写入XML数据

 using(FileStream fs = new FileStream(GlobalParams.XmlFileName,FileMode.Open,FileAccess.ReadWrite))
            {
                try
                {
                    XDocument doc = XDocument.Load(fs);
                    XElement element = new XElement("Email",
                        new XElement("EmailFrom", txtEmailAddress.Text.Trim()),
                        new XElement("MailHost", txtSMTP.Text.Trim()),
                        new XElement("EmailAccount", txtEmailAccount.Text.Trim()),
                        new XElement("EmailPassword", txtEmailPassword.Text.Trim()),
                        new XElement("SMTPPort", updSMTPPort.Value),
                        new XElement("EnableSSL", chkSSL.Checked)
                        );

                    if (!doc.Root.Descendants("EmailFrom").Any(ele => ele.Value == txtEmailAddress.Text.Trim()))
                    {
                        doc.Root.Element("Push_MLG").Add(element);
                        fs.SetLength(0);
                        doc.Save(fs);
                    }
                }
                catch (Exception ex)
                {
                    MessageBox.Show(string.Format("Failed:\t{0}", ex.Message));
                    return;
                }