提交方式：

<a
		href="${pageContext.request.contextPath}/product?method=findByPage2&category=文學">文學</a>
	<a
		href="${pageContext.request.contextPath}/product?method=findByPage2&category=生活">生活</a>
	<a
		href="${pageContext.request.contextPath}/product?method=findByPage2&category=計算機">計算機</a>
	<a
		href="${pageContext.request.contextPath}/product?method=findByPage2&category=外語">外語</a>
	<a
		href="${pageContext.request.contextPath}/product?method=findByPage2&category=經營">經管</a>
	<a
		href="${pageContext.request.contextPath}/product?method=findByPage2&category=勵誌">勵誌</a>
	<a
		href="${pageContext.request.contextPath}/product?method=findByPage2&category=社科">社科</a>
	<a
		href="${pageContext.request.contextPath}/product?method=findByPage2&category=學術">學術</a>
	<a
		href="${pageContext.request.contextPath}/product?method=findByPage2&category=少兒">少兒</a>
	<a
		href="${pageContext.request.contextPath}/product?method=findByPage2&category=藝術">藝術</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=考試">考試</a>

三層架構：

ProductServlet
	/**
	 * 根據類別查詢並分頁
	 * @param request
	 * @param response
	 * @throws ServletException
	 * @throws IOException
	 */
	public void findByPage2(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
	
		//獲取分類
		String category=request.getParameter("category");
		System.out.println(category);
		
		//一般情況下，服務器默認的編碼是“iso8859-1”，所以我們需要數據還原，然後再轉換成UTF-8的形式
		//如果要調用request.setCharacterEncoding進行編碼設置，一定要在任何參數被訪問之前調用。
		//if(category!=null){
		//	category=new String(category.getBytes("iso8859-1"),"utf-8");
		//}
		
		
		//獲取頁碼
		int pageCode=getPageCode(request);
		//每頁顯示的記錄條數
		int pageSize=4;
		//調用業務層
		ProductService ps=new ProductService();
		
		//分類分頁的查詢
		PageBean page=ps.findByPage(pageCode,pageSize,category);
		
		request.setAttribute("page", page);
		request.getRequestDispatcher("/product_list.jsp").forward(request, response);
		
	}

ProductService
	/**
	 *  根據類別查詢並分頁
	 * @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
	/**
	 * 根據類別查詢並分頁
	 * @param pageCode
	 * @param pageSize
	 * @param category
	 * @return
	 */
	public PageBean findByPage(int pageCode, int pageSize, String category) {
		
		//存儲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 {
			//查詢總記錄的條數
			long totalCount=(long) runner.query(countSql, new ScalarHandler(),list.toArray());
			//設置條數
			page.setTotalCount((int)totalCount);
			
			list.add((pageCode-1)*pageSize);
			list.add(pageSize);
			
			//查詢每頁顯示的條數
			List<Product> beanList=runner.query(selSql, new BeanListHandler<Product>(Product.class),list.toArray());
			page.setBeanList(beanList);
			
		} catch (SQLException e) {
			e.printStackTrace();
		}		
		return page;
	}

10.按類別查詢分頁