最近一直在看DDD开发 规约似乎用得很普遍。 但是还是理解不了。所以记录下学习的进度。～
规约（Specification）模式
目的：查询语句和查询条件的分离
写了一个关于规约的模拟小程序
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class
Program { static
void Main(string[] args) { for
(int
i = 0; i < 10; i++) { OrderInfo o = new
OrderInfo() { ID = i + 1, OrderTime = DateTime.Now, PorductID = new
Random().Next(800, 810), Price = new
Random().Next(123, 321), UserID = i + 1, UserName = "ZZQ"
+ i.ToString() }; SimulateDataBase.Add(o); } IRepository<OrderInfo> orderRespository = new
OrderRepository(); OrderInfo orderInfo = orderRespository.GetEntity(new
OrderInfoSpecification(2)); Console.WriteLine(orderInfo.UserName); Console.Read(); } } public
class OrderInfo { public
int ID { get; set; } public
int UserID { get; set; } public
string UserName { get; set; } public
int PorductID { get; set; } public
decimal Price { get; set; } public
DateTime OrderTime { get; set; } } public
interface IRepository<TEntity> where
TEntity : class,new() { void
Add(TEntity entity); IEnumerable<TEntity> GetEntitys(ISpecification<TEntity> specification); TEntity GetEntity(ISpecification<TEntity> specification); } public
interface IOrderRepository : IRepository<OrderInfo> { } public
class OrderRepository : IOrderRepository { public
void Add(OrderInfo entity) { SimulateDataBase.Add(entity); } public
IEnumerable<OrderInfo> GetEntitys(ISpecification<OrderInfo> specification) { return
SimulateDataBase.OrderInfoList.Where(specification.IsSatisfiedBy); } public
OrderInfo GetEntity(ISpecification<OrderInfo> specification) { return
SimulateDataBase.OrderInfoList.Where(specification.IsSatisfiedBy).FirstOrDefault(); } } public
interface ISpecification<TEntity> { bool
IsSatisfiedBy(TEntity obj); //ISpecification<TEntity> And(ISpecification<TEntity> other); //ISpecification<TEntity> Or(ISpecification<TEntity> other); //ISpecification<TEntity> AndNot(ISpecification<TEntity> other); //ISpecification<TEntity> Not(); Expression<Func<TEntity, bool>> GetExpression(); } public
abstract class Specification<TEntity> : ISpecification<TEntity> { public
bool IsSatisfiedBy(TEntity obj) { return
this.GetExpression().Compile()(obj); } public
abstract Expression<Func<TEntity, bool>> GetExpression(); } public
class OrderInfoSpecification : Specification<OrderInfo> { //private readonly OrderInfo order; //public OrderInfoSpecification(OrderInfo order) //{ // this.order = order; //} private
readonly int userId; public
OrderInfoSpecification(int
userId) { this.userId = userId; } public
override Expression<Func<OrderInfo, bool>> GetExpression() { return
x => x.UserID == userId; } } public
static class SimulateDataBase { private
static List<OrderInfo> orderInfoList = new
List<OrderInfo>(); public
static IList<OrderInfo> OrderInfoList { get
{ return
orderInfoList; } } public
static void Add(OrderInfo order) { orderInfoList.Add(order); } } |
原文：http://www.cnblogs.com/since87/p/3545211.html