我对petshop4的简单理解！[通俗易懂]

petshop4充分体现了面向接口编程的思想，就是给你一个接口你别管我是怎么实现的，你只管用别说其他的。

namespace PetShop.BLL {

/// <summary> /// A business component to manage products /// </summary> public class Product {

// Get an instance of the Product DAL using the DALFactory // Making this static will cache the DAL instance after the initial load private static readonly IProduct dal = PetShop.DALFactory.DataAccess.CreateProduct();

在bll层，这里使用创建Produce的接口，你只管调用他的方法。

namespace PetShop.IDAL{ /// <summary> /// Interface for the Product DAL /// </summary> public interface IProduct{ /// <summary> /// Method to search products by category name /// </summary> /// <param name=”category”>Name of the category to search by</param> /// <returns>Interface to Model Collection Generic of search results</returns> IList<ProductInfo> GetProductsByCategory(string category);

/// <summary> /// Method to search products by a set of keyword /// </summary> /// <param name=”keywords”>An array of keywords to search by</param> /// <returns>Interface to Model Collection Generic of search results</returns> IList<ProductInfo> GetProductsBySearch(string[] keywords);

/// <summary> /// Query for a product /// </summary> /// <param name=”productId”>Product Id</param> /// <returns>Interface to Model ProductInfo for requested product</returns> ProductInfo GetProduct(string productId); }

这里是定义了Product接口和他的虚方法。

namespace PetShop.SQLServerDAL {

public class Product : IProduct {

//Static constants private const string SQL_SELECT_PRODUCTS_BY_CATEGORY = “SELECT Product.ProductId, Product.Name, Product.Descn, Product.Image, Product.CategoryId FROM Product WHERE Product.CategoryId = @Category”; private const string SQL_SELECT_PRODUCTS_BY_SEARCH1 = “SELECT ProductId, Name, Descn, Product.Image, Product.CategoryId FROM Product WHERE ((“; private const string SQL_SELECT_PRODUCTS_BY_SEARCH2 = “LOWER(Name) LIKE ‘%’ + {0} + ‘%’ OR LOWER(CategoryId) LIKE ‘%’ + {0} + ‘%'”; private const string SQL_SELECT_PRODUCTS_BY_SEARCH3 = “) OR (“; private const string SQL_SELECT_PRODUCTS_BY_SEARCH4 = “))”; private const string SQL_SELECT_PRODUCT = “SELECT Product.ProductId, Product.Name, Product.Descn, Product.Image, Product.CategoryId FROM Product WHERE Product.ProductId = @ProductId”; private const string PARM_CATEGORY = “@Category”; private const string PARM_KEYWORD = “@Keyword”; private const string PARM_PRODUCTID = “@ProductId”;

/// <summary> /// Query for products by category /// </summary> /// <param name=”category”>category name</param> /// <returns>A Generic List of ProductInfo</returns> public IList<ProductInfo> GetProductsByCategory(string category) {

IList<ProductInfo> productsByCategory = new List<ProductInfo>();

这里是实现Product接口的类，

namespace PetShop.DALFactory {

/// <summary> /// This class is implemented following the Abstract Factory pattern to create the DAL implementation /// specified from the configuration file /// </summary> public sealed class DataAccess {

// Look up the DAL implementation we should be using private static readonly string path = ConfigurationManager.AppSettings[“WebDAL”]; private static readonly string orderPath = ConfigurationManager.AppSettings[“OrdersDAL”]; private DataAccess() { }

public static PetShop.IDAL.ICategory CreateCategory() { string className = path + “.Category”; return (PetShop.IDAL.ICategory)Assembly.Load(path).CreateInstance(className); }

这里是利用工厂模式来映射你需要你想创建哪一个。

后面还有一些消息队列MSMQMessage利用cache缓存以后达到异步处理购物车里订单的功能！

刚开始看应先从先从Product入口，关于Product的一些操作串联起来看一遍！

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