序列化(和反序列化)XML列表

我在序列化一些c#字段到XML文件时遇到了一些问题。下面是我的代码:

public class Facility
{
    public string ID = "";
    public string Name = "";
    public List<Profile> Profiles { get; set; }
}
public class PrefSet
{
    public string SomeItem = "";
    public string AnotherItem = "";
}
public class Config
{
    public string Username = "";
    public string Password = "";
    public List<Facility> Facilities { get; set; }
    public static void SerializeObjectToFile<T>(T dataToSerialize, string filePath)
    {
        try
        {
            using (Stream stream = File.Open(filePath, FileMode.Create, FileAccess.ReadWrite))
            {
                XmlSerializer serializer = new XmlSerializer(typeof(T));
                XmlTextWriter writer = new XmlTextWriter(stream, Encoding.Default);
                writer.Formatting = Formatting.Indented;
                serializer.Serialize(writer, dataToSerialize);
                writer.Close();
            }
        }
        catch
        {
            File.Create(filePath);
        }
    }
    public static T DeserializeObjectFromFile<T>(string filePath)
    {
        try
        {
            XmlSerializer serializer = new XmlSerializer(typeof(T));
            T serializedData;
            using (Stream stream = File.Open(filePath, FileMode.Open, FileAccess.Read))
            {
                serializedData = (T)serializer.Deserialize(stream);
            }
            return serializedData;
        }
        catch
        {
            throw;
        }
    }
}

我想配置它，这样我将有一个这样的XML输出:

<?xml version="1.0" encoding="Windows-1252"?>
<Config xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xmlns:xsd="http://www.w3.org/2001/XMLSchema">
  <Username>admin</Name>
  <Password>123456</VoiceServer>
  <Facilities>
    <Facility>
      <ID>1</ID>
      <Name>First Facility</Name>
      <Profiles>
        <Profile>
          <SomeItem>Value</SomeItem>
          <AnotherItem>Value</AnotherItem>
        </Profile>
        <Profile>
          <SomeItem>Value</SomeItem>
          <AnotherItem>Value</AnotherItem>
        </Profile>
        <Profile>
          <SomeItem>Value</SomeItem>
          <AnotherItem>Value</AnotherItem>
        </Profile>
      </Profiles>
    </Facility>
    <Facility>
      <ID>2</ID>
      <Name>Second Facility</Name>
      <Profiles>
        <Profile>
          <SomeItem>Value</SomeItem>
          <AnotherItem>Value</AnotherItem>
        </Profile>
        <Profile>
          <SomeItem>Value</SomeItem>
          <AnotherItem>Value</AnotherItem>
        </Profile>
        <Profile>
          <SomeItem>Value</SomeItem>
          <AnotherItem>Value</AnotherItem>
        </Profile>
      </Profiles>
    </Facility>
  </Facilities>
</Config>

注意可以有多个Profile和Facility列表。

下面是我用来执行序列化的代码:

Config config = new Config();
Facility fac = new Facility();
Profile prof = new Profile();
if (File.Exists(CONFIG_FILE)) config = Config.DeserializeObjectFromFile<Config>(CONFIG_FILE);
fac.ID = "1";
fac.Name = "Facility One";
prof.SomeItem = "Value";
prof.AnotherItem = "Value";
config.Facilities.Add(fac);
fac.Profiles.Add(prof);

Config.SerializeObjectToFile<Config>(config, CONFIG_FILE);

另外，例如，我希望能够编辑和保存对项目的更改。

我遇到的问题是，它将创建XML格式，但如果我改变一个值，它将创建一个全新的Facility项，而不是更新现有的Facility列表项。