一、流程分析
二、代码
1.view层
(1)msg.jsp
1 <body> 2 <h2>${msg }</h2> 3 <input type="button" value="返回" onclick="history.go(-1)"/> 4 </body> 5 </html>
2.servlet层
(1)AdminCategoryServlet.java
1 /** 2 * 删除一级分类 3 * @param req 4 * @param resp 5 * @return 6 * @throws ServletException 7 * @throws IOException 8 */ 9 public String deleteParent(HttpServletRequest req, HttpServletResponse resp) 10 throws ServletException, IOException { 11 String cid = req.getParameter("cid"); 12 int count = service.findChildCountByParent(cid); 13 if(count > 0) { 14 req.setAttribute("code", "eror"); 15 req.setAttribute("msg", "该分类下还有子分类，不能删除！"); 16 return "/adminjsps/msg.jsp"; 17 } 18 service.delete(cid); 19 return findAll(req, resp); 20 }
3.service层
(1)AdminCategoryService.java
1 /** 2 * 查询子类个数 3 * @param cid 4 * @return 5 */ 6 public int findChildCountByParent(String cid) { 7 try { 8 return categoryDao.findChildCountByparent(cid); 9 } catch (SQLException e) { 10 throw new RuntimeException(e); 11 } 12 } 13 14 /** 15 * 删除分类 16 * @param cid 17 */ 18 public void delete(String cid) { 19 try { 20 categoryDao.delete(cid); 21 } catch (SQLException e) { 22 throw new RuntimeException(e); 23 } 24 }
4.dao层
(1)AdminCategoryDao.java
1 /** 2 * 查询子类个数 3 * @param cid 4 * @return 5 * @throws SQLException 6 */ 7 public int findChildCountByparent(String cid) throws SQLException { 8 String sql = "select count(1) from t_category where pid=?"; 9 Number count = (Number) qr.query(sql, new ScalarHandler(), cid); 10 return count == null ? 0 : count.intValue(); 11 } 12 13 /** 14 * 删除分类 15 * @param cid 16 * @throws SQLException 17 */ 18 public void delete(String cid) throws SQLException { 19 String sql = "delete from t_category where cid=?"; 20 qr.update(sql, cid); 21 }