自定义延迟加载类

延迟加载类

    public class LazyLoader<TModel> where TModel:class
    {
        TModel _data;
        Func<TModel> _loadDataFunc = null;
        bool _loaded = false;
        public LazyLoader():this(null){ }
        public LazyLoader(Func<TModel> loadDataFunc) 
        {
            _loadDataFunc = loadDataFunc;
            _data = null;
            _loaded = false;
        }
        public TModel QueryData() 
        {
            if (!_loaded && _loadDataFunc != null)
            {
                _data = _loadDataFunc();
            }
            return _data;
        }
        public void SetData(TModel value) 
        {
            _data = value;
            _loaded = true;
        }
    }

使用方法（简单举列）

比如员工菜单 可能你再使用这个员工对象的时候并不需要去加载他的菜单 当你要用的时候再加载 这时候就需要延迟加载了 

    public class Employee
    {
        public LazyLoader<IEnumerable<Menu>> _menus;
        public Employee(Guid employeeId, string employeeNo, string name, string password, string email, string phone, bool enabled,  bool isAdministrtor, DateTime registerDate, string remark, string ipLimitation)
        {
            EmployeeId = employeeId;
            EmployeeNo = employeeNo;
            Name = name;
            Password = password;
            Email = email;
            Phone = phone;
            Enabled = enabled;
            IsAdministrator = isAdministrtor;
            RegisterDate = registerDate;
            Remark = remark;
            IpLimitation = ipLimitation;
            _menus = new LazyLoader<IEnumerable<Menu>>(() => SystemResourceService.QueryMenusByEmployeeId(employeeId));
        }

        public Guid EmployeeId { get; private set; }
        public string EmployeeNo { get; private set; }
        public string Name { get; private set; }
        public string Password { get; private set; }
        public string Email { get; private set; }
        public string Phone { get; private set; }
        public bool Enabled { get; set; }
        public bool IsAdministrator { get; private set; }
        public DateTime RegisterDate { get; private set; }
        public string Remark { get; private set; }
        public string IpLimitation { get; set; }
        public object Id
        {
            get { return EmployeeId; }
        }
    }