[DataContract(Namespace = "")]
public class User
{
    [DataMember]
    public string UserName { get; set; }
 
    [DataMember]
    public string FullName { get; set; }
}
 
//Deserialization test
public void Test()
{
 
  //CASE 1.
  //string xml = "<User><UserName>john</UserName>" + 
  //                    "<FullName>John Lennon</FullName></User>";
 
  //CASE 2.
  string xml = "<User><FullName>John Lennon</FullName>" + 
                      "<UserName>john</UserName></User>";
 
 
  byte[] byteArray = Encoding.UTF8.GetBytes(xml);
  User user = null;
  using (MemoryStream stream = new MemoryStream(byteArray))
  {
    DataContractSerializer serializer = 
           new DataContractSerializer(typeof(User),"User","");
    user = (User)serializer.ReadObject(stream);
  }
}

在情况1中,FullName属性不反序列化,但是如果2它被反序列化正确.为什么？