.net 4.0的Lazy<T>方法，反射实现延迟加载。

//自己山寨。
public class YaLazy<T>
    {
        private bool _isValueCreated = false;
        public bool IsValueCreated
        {
            get
            {
                return _isValueCreated;
            }
        }
        private T _value;
        public T Value
        {
            get
            {
                if (this._value != null)
                {
                    return (T)_value;
                }
                return CreateValue();

            }
        }
        private T CreateValue()
        {
            _isValueCreated = true;
            _value = (T)Activator.CreateInstance(typeof(T));
            return _value;
        }
    }

使用方法和Lazy<T>类似:

YaLazy<Student> student2 = new YaLazy<Student>();
             Console.WriteLine(student2);
             student2.Value.ID = 23;
             student2.Value.Name = "New";
             Console.WriteLine(student2);

----------------------

或者使用官方用法：

Lazy<Student> student = newLazy<Student>();
  Console.WriteLine(student);
  student.Value.ID = 23;
  student.Value.Name = "New";
  Console.WriteLine(student);

延迟初始化Student:我们在Console.WriteLine(student);  一行设置断点查看,发现IsValueCreated是false ,Value值是null。