Java Web 网络商城案例演示九（首页热门商品和最新商品显示）

Java Web 网络商城案例演示九（首页热门商品和最新商品显示）

一、分析SQL语句的编写

查询数据库商品表当中最新的9件商品信息

-- 查询商品表中最新的9件商品信息
SELECT * FROM product WHERE pflag=0 ORDER BY pdate DESC LIMIT 0,9;
-- 查询来自（product的当中排序按降序0到9 并且有货 ）

-- 查询商品表中最热最新的9件商品信息
SELECT * FROM product WHERE pflag=0 AND is_hot=1 ORDER BY pdate DESC LIMIT 0,9;

二、原理分析

三、步骤实现

1、准备工作（放文页面就发送请求）：
2、在IndexServlet的execute的方法当中实现功能
调用业务层查询最新商品，查询最热商品，返回两个集合
将2个集合放入到request
转发到真实的首页
3、建立商品模块的相关的程序
ProdectServlet ProdectService ProdectServiceImpl ProductDao ProductDaoImpl Product

ProdectServlet

ProdectService

public interface ProductService {
	List<Product> findHots() throws Exception;
	List<Product> findNews() throws Exception;
}

ProdectServiceImpl

public class ProductServiceImpl implements ProductService {
	ProductDao productDao = new ProductDaoImpl();
	@Override
	public List<Product> findHots() throws Exception {
		// TODO Auto-generated method stub
		return productDao.findHots();
	}
	@Override
	public List<Product> findNews() throws Exception {
		// TODO Auto-generated method stub
		return productDao.findNews();
	}
}

ProductDao

public interface ProductDao {
	List<Product> findHots() throws Exception;
	List<Product> findNews() throws Exception;
}

ProductDaoImpl

public class ProductDaoImpl implements ProductDao {
	@Override
	public List<Product> findHots() throws Exception {
		// TODO Auto-generated method stub
		String sql = "SELECT * FROM product WHERE pflag=0 AND is_hot=1 ORDER BY pdate DESC LIMIT 0,9;";
		QueryRunner qr = new QueryRunner(JDBCUtils.getDataSource());
		return qr.query(sql, new BeanListHandler<Product>(Product.class));
	}
	@Override
	public List<Product> findNews() throws Exception {
		// TODO Auto-generated method stub
		String sql = "SELECT * FROM product WHERE pflag=0 ORDER BY pdate DESC LIMIT 0,9";
		QueryRunner qr = new QueryRunner(JDBCUtils.getDataSource());
		return qr.query(sql, new BeanListHandler<Product>(Product.class));
	}
}

3、调用service，和dao
IndexServlet当中

public class IndexServlet extends BaseServlet {
	@Override
	public String execute(HttpServletRequest request, HttpServletResponse resp) throws Exception {
		/*
		 * // 调用业务层的一个功能，获取全部的分类信息,返回集合 CategoryService categoryService = new
		 * CategoryServiceImpl(); List<Category> list = categoryService.getAllCats(); //
		 * 将返回的集合放入request内 request.setAttribute("allCats", list); // 转发到真实的首页
		 */				
		//调用业务层查询最新商品，查询最热商品，返回两个集合
		ProductService productService = new ProductServiceImpl();
		List<Product> list01 = productService.findHots();
		List<Product> list02 = productService.findNews();		
		//将2个集合放入到request		
		request.setAttribute("hots", list01);
		request.setAttribute("news", list02);		
		//转发到真实的首页	
		return "/jsp/index.jsp";
	}
}

4、在index.jsp当中所以遍历的方式获取到IndexServlet当中的数据（删除重复的数据）

<c:forEach items="${hots }" var="p">
					<div class="col-md-2"
						style="text-align: center; height: 200px; padding: 10px 0px;">
						<a href="product_info.htm"> <img
							src="${pageContext.request.contextPath}/${p.pimage}" width="130" height="130"
							style="display: inline-block;">
						</a>
						<p>
							<a href="product_info.html" style='color: #666'>${p.pname }</a>
						</p>
						<p>
							<font color="#E4393C" style="font-size: 16px">&yen;${p.shop_price }</font>
						</p>
					</div>
				</c:forEach>

<c:forEach items="${news }" var="p">
					<div class="col-md-2"
						style="text-align: center; height: 200px; padding: 10px 0px;">
						<a href="product_info.htm"> <img
							src="${pageContext.request.contextPath}/${p.pimage}" width="130" height="130"
							style="display: inline-block;">
						</a>
						<p>
							<a href="product_info.html" style='color: #666'>${p.pname }</a>
						</p>
						<p>
							<font color="#E4393C" style="font-size: 16px">&yen;${p.shop_price }</font>
						</p>
					</div>
				</c:forEach>