网上商城2---分类管理

分类管理：查询所有分类

准备工作:

创建数据库表、javabean、dao接口和实现类、service接口和实现类

步骤一：创建分类表

步骤二：创建javabean Category

步骤三：编写dao接口、及其实现类

步骤四：编写service

代码实现

步骤一：完善IndexServlet，显示/jsp/index.jsp查询分类

public class IndexServlet extends HttpServlet {

	protected void doGet(HttpServletRequest request, HttpServletResponse response)
			throws ServletException, IOException {
		
		ProductService service = new ProductService();
		//查询所有分类
		//List<Category> categoryList = service.findAllCategory();

              //将查询结果存放到request作用域

              //request.setAttribute("categoryList", categoryList);

request.getRequestDispatcher("/index.jsp").forward(request, response);}

步骤二：完善CategoryService，提供findAll()方法

	实现类

public List<Category> findAllCategory() {

		ProductDao dao = new ProductDao();
		List<Category> categoryList = null;
		try {
			categoryList = dao.findAllCategory();
		} catch (SQLException e) {
			e.printStackTrace();
		}
		return categoryList;
	}

步骤三：完善CategoryDao,提供findAll（）方法

public List<Category> findAllCategory() throws SQLException {
		QueryRunner runner = new QueryRunner(DataSourceUtils.getDataSource());
		String sql = "select * from category";
		return runner.query(sql, new BeanListHandler<Category>(Category.class));
	}

步骤四：遍历数据

<ul class="nav navbar-nav" id="categoryUl">
				
					<%-- <c:forEach items="${categoryList }" var="category">
						<li><a href="#">${category.cname }</a></li>
					</c:forEach> --%>
					
				</ul>

优化:Ajax异步加载

1、修改header.jsp。添加js函数，页面加载发送ajax查询所有分类

2、编写CategoryServlet，提供findAll()方法

增强：缓存技术

代码实现

redis.properties