创建监听器
- 将商品分类的数据查询
public class TypeDao {
public List selectAll() throws SQLException {
//取得数据库连接
QueryRunner r = new QueryRunner(DBUtils.getDataSource());
String sql = "select * from type";
return r.query(sql, new BeanListHandler(Type.class));
}
}
- 将查询结果返回并由类 TypeService 中的方法调用返回
public class TypeService {
private TypeDao tDao = new TypeDao();
public List selectAll(){
List list = null;
try {
list = tDao.selectAll();
} catch (SQLException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
return list;
}
}
- ApplicationListener监听器在项目启动时，开始查询得到数据，将商品分类的数据显示
//创建TypeService对象
private TypeService tService = new TypeService();
public void contextInitialized(ServletContextEvent arg0) {
// TODO Auto-generated method stub
List list = tService.selectAll();
arg0.getServletContext().setAttribute("typeList", list);
}
创建分页的数据模型
//分页的数据模型
public class Page {
private int pageNumber;//当前页数
private int pageSize;//每页显示的数据个数
private int totalCount;//商品的总数
private int totalPage;//总页数
private List
根据 每页商品的个数 和 商品总数 计算 总页数 的方法
public void setPageSizeAndTotalCount(int pageSize,int totalCount) {
this.pageSize = pageSize;
this.totalCount = totalCount;
totalPage = (int) Math.ceil((double)totalCount/pageSize);
}
创建servlet控制商品分类的页面跳转
protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
// TODO Auto-generated method stub
int id = 0;//id为0时跳转的是全部系列
if(request.getParameter("id") != null) {
id = Integer.parseInt(request.getParameter("id"));
}
//默认跳转的页面
int pageNo = 1;
if(request.getParameter("pageNo") != null) {
pageNo = Integer.parseInt(request.getParameter("pageNo"));
}
Page p = gService.getGoodsPage(id, pageNo);
request.setAttribute("p", p);
//跳转到goods_list.jsp
request.getRequestDispatcher("/goods_list.jsp").forward(request, response);
}
商品分类中系列的商品查询
public ListselectGoods(int typeId,int pageNo,int pageSize) throws SQLException{ QueryRunner r = new QueryRunner(DBUtils.getDataSource()); //查询全部系列 if(typeId == 0) { String sql = "select * from goods limit ?,?"; return r.query(sql, new BeanListHandler (Goods.class),(pageNo - 1)*pageSize, pageSize); }else {//查询其他系列 String sql = "select * from goods where type_id = ? limit ?,?"; return r.query(sql, new BeanListHandler (Goods.class), typeId, (pageNo - 1)*pageSize, pageSize); } }
查询商品的总数
public int getGoodsCount(int typeId) throws SQLException {
QueryRunner r = new QueryRunner(DBUtils.getDataSource());
String sql = "";
if(typeId == 0) {
sql = "select count(*) from goods";
return r.query(sql, new ScalarHandler()).intValue();
}else {//查询其他系列
sql = "select count(*) from goods where type_id = ?";
return r.query(sql, new ScalarHandler(),typeId).intValue();
}
}
在service层调用dao层的方法创建分页的数据模型并返回商品的页数
public Page getGoodsPage(int typeId,int pageNo) {
Page p = new Page();
p.setPageNumber(pageNo);
int totalCount = 0;
try {
totalCount = gDao.getGoodsCount(typeId);
} catch (SQLException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
p.setPageSizeAndTotalCount(8, totalCount);
List list = null;
try {
list = gDao.selectGoods(typeId, pageNo, 8);
} catch (SQLException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
p.setList(list);
return p;
}
最后在jsp页面中使用 c:forEach 标签遍历结果，在商品分类中点击系列商品可以跳转到各自的页面。
