运用 DataContractSerializer 存储本地对象

    public void Save(string filename,State state)
        {
            DataContractSerializer ds = new DataContractSerializer(typeof(State));
            using (FileStream fs = new FileStream(GetLocalTempdataPath(filename), FileMode.Create))
            {
                ds.WriteObject(fs, state);
                fs.Close();
            }
        }

    public State Load(string filename)
        {
            try
            {
                DataContractSerializer ds = new DataContractSerializer(typeof(State));
                FileStream fs = new FileStream(GetLocalTempdataPath(filename), FileMode.OpenOrCreate);
                var result = (State)ds.ReadObject(fs);
                fs.Close();
                return result;
            }
            catch (Exception)
            {
                return null;
            }
        }

    private string GetLocalTempdataPath(string filename)
        {
            return Path.Combine(AppDomain.CurrentDomain.BaseDirectory,
                string.Format("{0}.dat", filename));
        }

　　[DataContract]
    public class State
    {
        [DataMember]
        public string Id{ get; set; }
    }