10.按类别查询分页

<a
		href="${pageContext.request.contextPath}/product?method=findByPage2&category=文学">文学</a>
	<a
		href="${pageContext.request.contextPath}/product?method=findByPage2&category=生活">生活</a>
	<a
		href="${pageContext.request.contextPath}/product?method=findByPage2&category=计算机">计算机</a>
	<a
		href="${pageContext.request.contextPath}/product?method=findByPage2&category=外语">外语</a>
	<a
		href="${pageContext.request.contextPath}/product?method=findByPage2&category=经营">经管</a>
	<a
		href="${pageContext.request.contextPath}/product?method=findByPage2&category=励志">励志</a>
	<a
		href="${pageContext.request.contextPath}/product?method=findByPage2&category=社科">社科</a>
	<a
		href="${pageContext.request.contextPath}/product?method=findByPage2&category=学术">学术</a>
	<a
		href="${pageContext.request.contextPath}/product?method=findByPage2&category=少儿">少儿</a>
	<a
		href="${pageContext.request.contextPath}/product?method=findByPage2&category=艺术">艺术</a>
	<a
		href="${pageContext.request.contextPath}/product?method=findByPage2&category=原版">原版</a>
	<a
		href="${pageContext.request.contextPath}/product?method=findByPage2&category=科技">科技</a>
	<a
		href="${pageContext.request.contextPath}/product?method=findByPage2&category=考试">考试</a>

ProductServlet
	/**
	 * 根据类别查询并分页
	 * @param request
	 * @param response
	 * @throws ServletException
	 * @throws IOException
	 */
	public void findByPage2(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
	
		//获取分类
		String category=request.getParameter("category");
		System.out.println(category);
		
		//一般情况下，服务器默认的编码是“iso8859-1”，所以我们需要数据还原，然后再转换成UTF-8的形式
		//如果要调用request.setCharacterEncoding进行编码设置，一定要在任何参数被访问之前调用。
		//if(category!=null){
		//	category=new String(category.getBytes("iso8859-1"),"utf-8");
		//}
		
		
		//获取页码
		int pageCode=getPageCode(request);
		//每页显示的记录条数
		int pageSize=4;
		//调用业务层
		ProductService ps=new ProductService();
		
		//分类分页的查询
		PageBean page=ps.findByPage(pageCode,pageSize,category);
		
		request.setAttribute("page", page);
		request.getRequestDispatcher("/product_list.jsp").forward(request, response);
		
	}

ProductService
	/**
	 *  根据类别查询并分页
	 * @param pageCode
	 * @param pageSize
	 * @param category
	 * @return
	 */
	public PageBean findByPage(int pageCode, int pageSize, String category) {
		ProductDao dao=new ProductDao();
		return dao.findByPage(pageCode,pageSize,category);
	}

ProductDao
	/**
	 * 根据类别查询并分页
	 * @param pageCode
	 * @param pageSize
	 * @param category
	 * @return
	 */
	public PageBean findByPage(int pageCode, int pageSize, String category) {
		
		//存储cansh
		List<Object> list=new ArrayList();
		
		PageBean<Product> page=new PageBean<Product>();
		page.setPageCode(pageCode);
		page.setPageSize(pageSize);
	
		QueryRunner runner=new QueryRunner(MyJdbcUtils.getDataSource());
		
		String countSql=null;
		String selSql=null;
		
		if(category!=null){
			countSql="select count(*) from products where category=?";
			selSql="select * from products where category=? limit ?,?";
			list.add(category);
		}else{
			countSql="select count(*) from products ";
			selSql="select * from products limit ?,?";
		}
		
		try {
			//查询总记录的条数
			long totalCount=(long) runner.query(countSql, new ScalarHandler(),list.toArray());
			//设置条数
			page.setTotalCount((int)totalCount);
			
			list.add((pageCode-1)*pageSize);
			list.add(pageSize);
			
			//查询每页显示的条数
			List<Product> beanList=runner.query(selSql, new BeanListHandler<Product>(Product.class),list.toArray());
			page.setBeanList(beanList);
			
		} catch (SQLException e) {
			e.printStackTrace();
		}		
		return page;
	}