思考一种好的架构（八）

库存业务服务库：

 [Table("Stock")]
    public class StockEntity
    {
        [ColumnAttribute(IsPrimaryKey = true)]
        [AutoIncrement]
        public int ID { get; set; }

        /// <summary>  
        /// 商品ID
        /// </summary>
        public int ProductID { get; set; }

        /// <summary> 
        /// 数量
        /// </summary>
        public int Number { get; set; }
    }

 public class StockServer : IStock
    {
        IDbContext DC;
        public StockServer(IDbContext DC)
        {
            this.DC = DC;
        }

        public IQuery<StockDTO> GetSingle(int productID)
        {
            return DC.Query<StockEntity>().Where(x => x.ProductID.Equals(productID)).Select(x=>new StockDTO() { 
                ID=x.ID,
                Number=x.Number,
                ProductID=x.ProductID
            });
        }

        public bool ReducedInventory(int productID, int number)
        {
            var result = DC.Update<StockEntity>(x => x.ProductID.Equals(productID) && x.Number > 0, d => new StockEntity()
            {
                Number = d.Number - number
            });
            if (result > 0)
            {
                return true;
            }
            else
            {
                return false;
            }

        }

        public IQuery<StockDTO> StockNumberQuery(int? minNumber, int? maxNumber)
        {
            var result = DC.Query<StockEntity>()
                .EmptyCheck(minNumber, x => x.Number >= minNumber)
                .EmptyCheck(maxNumber, x => x.Number <= maxNumber);
            return result.Select(x => new StockDTO()
            {
                ID = x.ID,
                Number = x.Number,
                ProductID = x.ProductID
            });
        }
    }

  public static void ConfigureServices(IServiceCollection services)
        {
            services.AddTransient<IStock, StockServer>();
        }

        public static void Configure(IApplicationBuilder app, IHostingEnvironment env)
        {
            
        }

上节有提到库存服务，这节不再赘述

订单服务：

 [APIRouth("Order")]
    [ApiController]
    public class OrderController : Controller
    {
        IOrder orderServer;
        public OrderController(IOrder orderServer)
        {
            this.orderServer = orderServer;
        }
       
        [HttpGet]
        [Command]
        public IActionResult GenerateOrder(int productID, int number)
        {
            var result = orderServer.GenerateOrder(productID, number);
            return Json(result);
        }
    }

 [ColumnAttribute(IsPrimaryKey =true)]
        [AutoIncrement]
        public int ID { get; set; }

        /// <summary>
        /// 商品ID
        /// </summary>
        public int ProductID { get; set; }

        /// <summary>
        /// 数量
        /// </summary>
        public int Number { get; set; }

        /// <summary>
        /// 创建时间
        /// </summary>
        public DateTime CreateTimer { get; set; }

public class OrderServer : IOrder
    {
        IDbContext DC;
        IProduct product;
        IStock stock;
        IMediator mediator;
        public OrderServer(IDbContext DC, IProduct product, IStock stock, IMediator mediator)
        {
            this.mediator = mediator;
            this.product = product;
            this.DC = DC;
            this.stock = stock;
        }
        public bool GenerateOrder(int productID, int number)
        {
            var productDto = product.GetSingle(productID);
            if (productDto == null)
            {
                throw new Exception("商品未找到");
            }
            if (!stock.ReducedInventory(productID, number))
            {
                throw new Exception("库存不足");
            }
            if (new Random().Next(100) > 50)
            {
                throw new Exception("测试回滚库存");
            }
            mediator.Publish(new OrderGenerationEvent(DateTime.Now, number) { });
            return true;
        }

Command特性头表示这次请求时写操作请求

这里有提到mediator，事件总线（EventBus）

之前的CQRS也有提及，事件总线具体后续再说

 public static class Startup
    {
        public static void ConfigureServices(IServiceCollection services)
        {
            services.AddTransient<IOrder, OrderServer>();
        }

        public static void Configure(IApplicationBuilder app, IHostingEnvironment env)
        {
            
        }
    }