/// <summary>
/// 数据集基类
/// </summary>
/// <typeparam name="T"></typeparam>
public abstract class BaseTB<T>
    where T : class
{
    private static string _TextFile = Path.Combine(ConfigurationManager.AppSettings["TextDBDir"], typeof(T).Name + "TB.txt");
    private static List<T> _data = null;

    /// <summary>
    /// 数据容器
    /// </summary>
    internal static List<T> Container
    {
        get
        {
            if (_data == null)
            {
                if (File.Exists(_TextFile))
                {
                    _data = JsonHelper.Deserialize<List<T>>(File.ReadAllText(_TextFile));
                }
                else
                {
                    _data = new List<T>();
                }
            }
            return _data;
        }
    }

    /// <summary>
    /// 获取记录
    /// </summary>
    /// <param name="obj"></param>
    /// <returns></returns>
    public abstract T Get(T obj);

    /// <summary>
    /// 属性复制
    /// </summary>
    /// <param name="obj1"></param>
    /// <param name="obj2"></param>
    public abstract void Copy(T obj1, T obj2);

    /// <summary>
    /// 添加记录
    /// </summary>
    /// <param name="obj"></param>
    /// <returns></returns>
    public bool Add(T obj)
    {
        bool result = false;

        T item = Get(obj);
        if (item == null)
        {
            Container.Add(obj);
            Save();
            result = true;
        }

        return result;
    }

    /// <summary>
    /// 更新记录
    /// </summary>
    /// <param name="obj"></param>
    /// <returns></returns>
    public bool Update(T obj)
    {
        bool result = false;

        T item = Get(obj);
        if (item != null)
        {
            Copy(item, obj);
            Save();
            result = true;
        }

        return result;
    }

    /// <summary>
    /// 删除记录
    /// </summary>
    /// <param name="obj"></param>
    /// <returns></returns>
    public bool Remove(T obj)
    {
        bool result = false;

        T item = Get(obj);
        if (item != null)
        {
            Container.Remove(item);
            Save();
            result = true;
        }

        return result;
    }

    /// <summary>
    /// 保存数据
    /// </summary>
    internal void Save()
    {
        File.WriteAllText(_TextFile, JsonHelper.Serialize(Container));
    }
}

/// <summary>
/// 实体类
/// </summary>
public class User
{
    public string Usn { get; set; }
    public string Pwd { get; set; }
}

/// <summary>
/// 数据集
/// </summary>
public class UserTB : BaseTB<User>
{      
    #region 实现父类方法

    /// <summary>
    /// 获取对象
    /// </summary>
    /// <param name="user"></param>
    /// <returns></returns>
    public override User Get(User user)
    {
        return Get(user.Usn);
    }

    /// <summary>
    /// 属性复制
    /// </summary>
    /// <param name="user1"></param>
    /// <param name="user2"></param>
    public override void Copy(User user1, User user2)
    {
        user1.Usn = user2.Usn;
        user1.Pwd = user2.Pwd;
    }

    #endregion

    /// <summary>
    /// 获取对象
    /// </summary>
    /// <param name="usn"></param>
    /// <returns></returns>
    public User Get(string usn)
    {
        User result = null;

        foreach (User item in Container)
        {
            if (item.Usn.ToLower() == usn.ToLower())
            {
                result = item;
                break;
            }
        }

        return result;
    }

    /// <summary>
    /// 删除记录
    /// </summary>
    /// <param name="usn"></param>
    public void Remove(string usn)
    {
        User user = new User() { Usn = usn };
        Remove(user);
    }
}

/// <summary>
/// 数据库
/// </summary>
public static class Database
{
    /// <summary>
    /// 初始化
    /// </summary>
    static Database()
    {
        if (!Directory.Exists(ConfigurationManager.AppSettings["TextDBDir"]))
        {
            Directory.CreateDirectory(ConfigurationManager.AppSettings["TextDBDir"]);
        }
    }

    private static UserTB _usertb;
    /// <summary>
    /// UserTB
    /// </summary>
    public static UserTB UserTB
    {
        get
        {
            if (_usertb == null)
            {
                _usertb = new UserTB();
            }
            return _usertb;
        }
    }
}

User user = new User() { Usn = "dnawo", Pwd = "666666" };
Database.UserTB.Add(user);
user.Pwd = "999999";
Database.UserTB.Update(user);