将数据附加到现有xml文件而不将文件加载到内存中

Question

我想将数据添加到现有的xml文件中，而不必将现有文件加载到momory中。

我有一个数据模型：

public class clsPerson
{
    public string FirstName;
    public string LastName;
    public List<string> Likes;
}

我有这个代码，将两个人添加到xml文件，关闭文件，然后我想再添加两个人......

    static void Main(string[] args)
    {
        List<clsPerson> p1 = new List<clsPerson>();
        p1.Add(new clsPerson { FirstName = "John", LastName = "Dow", Likes = new List<string> { "Apples", "Bananas" } });
        p1.Add(new clsPerson { FirstName = "Jane", LastName = "Dow", Likes = new List<string> { "Football", "Tennis" } });

        string file = @"D:\people.xml";

        System.Xml.Serialization.XmlSerializer x = new System.Xml.Serialization.XmlSerializer(p1.GetType());
        TextWriter tw = new StreamWriter(file);
        x.Serialize(tw, p1);

        tw.Close();           


        List<clsPerson> p2 = new List<clsPerson>();

        p2.Add(new clsPerson { FirstName = "New", LastName = "Guy", Likes = new List<string> { "Reading", "Walking" } });
        p2.Add(new clsPerson { FirstName = "Another", LastName = "Girl", Likes = new List<string> { "Surfing", "Running" } });

        //... i want to add p2 to people.xml without having to load the entire file into memory again
}

我可以通过重新加载文件来添加两个新条目，将所有节点读入列表并添加新条目，但这似乎效率低下，特别是如果xml中有1000个条目。