分页数据展示后台代码
类别id传递
点击了不同的分类后将来看到的旅游线路不一样的。通过分析数据库表结构，发现
旅游线路表和分类表是一个多对一的关系
CategoryServiceImpl实现类：
public class CategoryServiceImpl implements CategoryService { private CategoryDao categoryDao = new CategoryDaoImpl(); @Override public List<Category> findAll() { //1、从redis中查询 //获取jedis客户端 Jedis jedis = JedisUtil.getJedis(); //可以使用sortedset排序查询 // Set<String> categorys = jedis.zrange("category", 0, -1); //1.3查询sortedset中的分数（cid）和值（cname） Set<Tuple> categorys = jedis.zrangeWithScores("category", 0, -1); List<Category> cs = null; //2、判断查询的集合是否为空 if (categorys == null || categorys.size()==0){ System.out.println("从数据库查询....."); //3、如果为空，需要从数据库查询，再将数据存入redis //从数据库查询 cs = categoryDao.findAll(); //将数据集合存储到redis中，category的key for (int i = 0; i < cs.size(); i++) { jedis.zadd("category",cs.get(i).getCid(),cs.get(i).getCname()); } }else { System.out.println("从redis查询....."); //4、如果不为空，直接返回 cs = new ArrayList<>(); for (Tuple tuple : categorys) { Category category = new Category(); category.setCname(tuple.getElement()); category.setCid((int) tuple.getScore()); cs.add(category); } } return cs; } }
header.html类：
<script> $(function () { $.get("user/findOne",{},function (data) { var msg = "欢迎回来,"+data.name; $("#span_username").html(msg); }); $.get("category/findAll",{},function (data) { var lis = '<li class="nav-active"><a href="https://www.cnblogs.com/xjw12345/p/index.html">首页</a></li>'; //遍历数组，拼接字符串 for (var i = 0; i < data.length; i++) { var li = '<li><a href="https://www.cnblogs.com/xjw12345/p/route_list.html?cid='+data[i].cid+'">'+data[i].cname+'</a></li>'; lis+=li; } lis+='<li><a href="https://www.cnblogs.com/xjw12345/p/favoriterank.html">收藏排行榜</a></li>'; //将lis字符串，设置到ul的html内容中 $("#category").html(lis); }); }); </script>
route_list.html页面：
<script> $(function () { var search = location.search; //切割字符串，拿到第二个值 var id = search.split("=")[1]; alert(id) }); </script>
分页数据展示分析
创建PageBean对象：
/** * 分页对象 */ public class PageBean<T> { private int totalCount;//总记录数 private int totalPage;//总页数 private int currentPage;//当前页码 private int pageSize;//每页显示的条数 private List<T> list;//每页显示的数据集合 @Override public String toString() { return "PageBean{" + "totalCount=" + totalCount + ", totalPage=" + totalPage + ", currentPage=" + currentPage + ", pageSize=" + pageSize + ", list=" + list + '}'; } public int getTotalCount() { return totalCount; } public void setTotalCount(int totalCount) { this.totalCount = totalCount; } public int getTotalPage() { return totalPage; } public void setTotalPage(int totalPage) { this.totalPage = totalPage; } public int getCurrentPage() { return currentPage; } public void setCurrentPage(int currentPage) { this.currentPage = currentPage; } public int getPageSize() { return pageSize; } public void setPageSize(int pageSize) { this.pageSize = pageSize; } public List<T> getList() { return list; } public void setList(List<T> list) { this.list = list; } }
RouteServlet类：
@WebServlet("/route/*")
public class RouteServlet extends BaseServlet {
private RouteService routeService = new RouteServiceImpl();
/**
* 分页查找
* @param request
* @param response
* @throws ServletException
* @throws IOException
*/
public void pageQuery(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
//接收参数
String currentPageStr = request.getParameter("currentPage");
String pageSizeStr = request.getParameter("pageSize");
String cidstr = request.getParameter("cid");
int cid = 0;
//2、处理参数
if (cidstr != null && cidstr.length()>0){
cid = Integer.parseInt(cidstr);
}
int currentPage = 0;//当前页码，如果不传递，则默认为第一页
if (currentPageStr!=null && currentPageStr.length()>0){
currentPage = Integer.parseInt(currentPageStr);
}else {
currentPage = 1;
}
int pageSize = 0;//每页显示条数，如果不传递，默认每页显示5条记录
if (pageSizeStr != null && pageSizeStr.length()==0){
pageSize = Integer.parseInt(pageSizeStr);
}else {
pageSize = 5;
}
//3、调用service查询pageBean对象
PageBean<Route> pb = routeService.pageQuery(cid, currentPage, pageSize);
//4、将pageBean对象序列化为json，返回
writeValue(pb,response);
}
}
RouteService接口：
/** * 线路service */ public interface RouteService { /** * 根据类别进行分页查询 * @param cid * @param currentPage * @param pageSize * @return */ public PageBean<Route> pageQuery(int cid,int currentPage,int pageSize); }
RouteServiceIpl实现类：
public class RouteServiceImpl implements RouteService { private RouteDao routeDao = new RouteDaoImpl(); @Override public PageBean<Route> pageQuery(int cid, int currentPage, int pageSize) { //封装PageBean PageBean<Route> pb = new PageBean<>(); //设置当前页码 pb.setCurrentPage(currentPage); //设置每页显示条数 pb.setPageSize(pageSize); //设置总记录数 int totalCount = routeDao.findTotalCount(cid); pb.setTotalCount(totalCount); //设置当前页显示的数据集合 int start = (currentPage-1)*pageSize; List<Route> list = routeDao.findByPage(cid, start, pageSize); pb.setList(list); //设置总页数 = 总记录数/每页显示条数 int totalPage = totalCount%pageSize==0 ? totalCount/pageSize : (totalCount/pageSize)+1; pb.setTotalPage(totalPage); return pb; } }
RouteDao接口：
public interface RouteDao { /** * 根据cid查询总记录数 */ public int findTotalCount(int cid); /** * 根据cid，start，pageSize查询当前页的数据集合 */ public List<Route> findByPage(int cid,int start,int pageSize); }
RouteDaoImpl实现类：
public class RouteDaoImpl implements RouteDao { private JdbcTemplate template = new JdbcTemplate(JDBCUtils.getDataSource()); @Override public int findTotalCount(int cid) { String sql = "select count(*) from tab_route where cid = ?"; return template.queryForObject(sql, Integer.class, cid); } @Override public List<Route> findByPage(int cid, int start, int pageSize) { String sql = "select * from tab_route where cid = ? limit ?,?"; return template.query(sql, new BeanPropertyRowMapper<>(Route.class), cid, start, pageSize); } }
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