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黑马旅游网学习笔记之旅游线路查询(七)

时间：2020-01-11 21:49:37

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黑马旅游网学习笔记之旅游线路查询(七)

概述

(一)参数传递

(二)后台代码

(三)前台代码

(一)参数传递

(二)后台代码

第一步，加上rname字段

然后分三种情况：第一种，直接在首页查询只有rname 没有cid第二种，进去之后在搜索框搜索有rname和cid第三种，进去之后不搜索只有cid 没有rname我们可以写一个sql的模板，应对以上三种情况

RouteServlet：

package cn.itcast.travel.web.servlet;import cn.itcast.travel.domain.PageBean;import cn.itcast.travel.domain.Route;import cn.itcast.travel.service.RouteService;import cn.itcast.travel.service.impl.RouteServiceImpl;import javax.servlet.ServletException;import javax.servlet.annotation.WebServlet;import javax.servlet.http.HttpServletRequest;import javax.servlet.http.HttpServletResponse;import java.io.IOException;@WebServlet("/route/*")public class RouteServlet extends BaseServlet {private RouteService routeService = new RouteServiceImpl();/*** 分页查询** @param request* @param response* @throws ServletException* @throws IOException*/public void pageQuery(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {//1.接受参数String currentPageStr = request.getParameter("currentPage");String pageSizeStr = request.getParameter("pageSize");String cidStr = request.getParameter("cid");//接受rname 线路名称String rname = request.getParameter("rname");//2.处理参数int cid = 0;//类别的idif (cidStr != null && cidStr.length() > 0) {cid = Integer.parseInt(cidStr);}int currentPage = 0;//当前页码if (currentPageStr != null && currentPageStr.length() > 0) {currentPage = Integer.parseInt(currentPageStr);} else {currentPage = 1;//如果不传递，则默认为第一页}int pageSize = 0;//每页显示条数if (pageSizeStr != null && pageSizeStr.length() > 0) {pageSize = Integer.parseInt(pageSizeStr);} else {pageSize = 5;//如果不传递，则默认一页显示5条记录}//3. 调用service查询PageBean对象PageBean<Route> pb = routeService.pageQuery(cid, currentPage, pageSize, rname);//4. 将pageBean对象序列化为json，返回writeValue(pb, response);}}

RouteServiceImpl：

package cn.itcast.travel.service.impl;import cn.itcast.travel.dao.RouteDao;import cn.itcast.travel.dao.impl.RouteDaoImpl;import cn.itcast.travel.domain.PageBean;import cn.itcast.travel.domain.Route;import cn.itcast.travel.service.RouteService;import java.util.List;public class RouteServiceImpl implements RouteService {private RouteDao routeDao = new RouteDaoImpl();/*** 分页查询* 根据cid,start,pageSize查询当前页的数据集合* start为查询结果的索引值(默认从0开始)* pageSize为查询结果返回的数量** @param cid* @param currentPage* @param pageSize* @return*/@Overridepublic PageBean<Route> pageQuery(int cid, int currentPage, int pageSize, String rname) {//封装PageBeanPageBean<Route> pb = new PageBean<Route>();//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, rname);pb.setTotalCount(totalCount);//设置当前页显示的数据集合int start = (currentPage - 1) * pageSize;//开始的记录数（已知当前处于第几页，一页显示多少条）公式：（当前页码 - 1）* 每页显示的记录数List<Route> list = routeDao.findByPage(cid, start, pageSize, rname);pb.setList(list);//设置总页数（总页数 = 总记录数 / 每页显示条数）注意判断能否除得尽，如果除不尽就加1int totalPage = totalCount % pageSize == 0 ? totalCount / pageSize : (totalCount / pageSize) + 1;pb.setTotalPage(totalPage);return pb;}}

RouteDaoImpl：

package cn.itcast.travel.dao.impl;import cn.itcast.travel.dao.RouteDao;import cn.itcast.travel.domain.Route;import cn.itcast.travel.util.JDBCUtils;import org.springframework.jdbc.core.BeanPropertyRowMapper;import org.springframework.jdbc.core.JdbcTemplate;import java.util.ArrayList;import java.util.List;public class RouteDaoImpl implements RouteDao {private JdbcTemplate template = new JdbcTemplate(JDBCUtils.getDataSource());/*** 根据cid查询总记录数** @param cid* @return*/@Overridepublic int findTotalCount(int cid, String rname) {//1.定义sql模板String sql = "select count(*) from tab_route where 1=1 ";StringBuilder sb = new StringBuilder(sql);List params = new ArrayList();//条件们//2.判断参数是否有值if (cid != 0) {sb.append(" and cid = ?");//要注意空格params.add(cid);//添加?对应的值}if (rname != null && rname.length() > 0) {sb.append(" and rname like ?");params.add("%" + rname + "%");}sql = sb.toString();return template.queryForObject(sql, Integer.class, params.toArray());}/*** 根据cid,start,pageSize查询当前页的数据集合* start为查询结果的索引值(默认从0开始)* pageSize为查询结果返回的数量*/@Overridepublic List<Route> findByPage(int cid, int start, int pageSize, String rname) {String sql = "select * from tab_route where 1=1 ";StringBuilder sb = new StringBuilder(sql);List params = new ArrayList();//条件们//2.判断参数是否有值if (cid != 0) {sb.append(" and cid = ?");//要注意空格params.add(cid);//添加?对应的值}if (rname != null && rname.length() > 0) {sb.append(" and rname like ?");params.add("%" + rname + "%");}sb.append(" limit ? , ? ");//分页条件sql = sb.toString();params.add(start);params.add(pageSize);return template.query(sql, new BeanPropertyRowMapper<Route>(Route.class), params.toArray());}}

我们测试发现使用tomcat7的话，get请求中文会乱码

访问：http://localhost/travel/route/pageQuery?cid=5&rname=西安

设置断点，然后step over

解决方法：

rname = new String(rname.getBytes("iso-8859-1"), "utf-8");

如果不这样解决，也可以换成tomcat8

效果：