public void CreateXML()
{

    //xml儲存的路徑，注意路徑。
    string filepath = "E:/my.xml";
    //繼續判斷當前路徑下是否有該檔案
    if(!File.Exists (filepath))
    {
        //建立XML文件例項
        XmlDocument xmlDoc = new XmlDocument();
        //建立root節點，也就是最上一層節點
        XmlElement root = xmlDoc.CreateElement("team");
        root.SetAttribute("name", "Dreamer");
        //繼續建立下一層節點
        XmlElement student = xmlDoc.CreateElement("student");
 
        //繼續建立下一層節點
        XmlElement name = xmlDoc.CreateElement("name");
        //設定節點中的數值
        name.InnerText = "Tom";
        XmlElement age = xmlDoc.CreateElement("age");
        age.InnerText = "20";
        XmlElement id = xmlDoc.CreateElement("id");
        id.InnerText = "20111234";

        //把節點一層一層的新增至XMLDoc中 ，請仔細看它們之間的先後順序，這將是生成XML檔案的順序
        student.AppendChild(name);
        student.AppendChild(age);
        student.AppendChild(id);
        root.AppendChild(student);

        student = xmlDoc.CreateElement("student");
        name = xmlDoc.CreateElement("name");
        name.InnerText = "Shierly";
        age = xmlDoc.CreateElement("age");
        age.InnerText = "19";
        id = xmlDoc.CreateElement("id");
        id.InnerText = "20113210";
        student.AppendChild(name);
        student.AppendChild(age);
        student.AppendChild(id);
        root.AppendChild(student);

        student = xmlDoc.CreateElement("student");
        name = xmlDoc.CreateElement("name");
        name.InnerText = "Lili";
        age = xmlDoc.CreateElement("age");
        age.InnerText = "21";
        id = xmlDoc.CreateElement("id");
        id.InnerText = "20111110";
        student.AppendChild(name);
        student.AppendChild(age);
        student.AppendChild(id);
        root.AppendChild(student);

        xmlDoc.AppendChild(root);
        //把XML檔案儲存至本地
        xmlDoc.Save(filepath);
    }

}