JavaWeb入门教程之分页查询功能的简单实现

 package com.ambow.utils; import java.util.List; public class PageBeanUtils { private int prePage;//上一页 private int nextPage;//下一页 private int firstPage=1;//首页 private int lastPage;//尾页 private int currentPage = 1;//当前 private int totalPage;//总页数 private int pageSize;//每页显示条数，默认显示10条 private int totalData;//数据总条数 private List pageData;//数据 public PageBeanUtils(int currentPage,int pageSize, int totalData) { this.currentPage = currentPage; this.pageSize = pageSize; this.totalData = totalData; //计算获得总页数（尾页） // this.totalPage = this.lastPage = (totalData+pageSize-1)/pageSize; this.totalPage = this.lastPage = (int)Math.ceil((double)totalData/pageSize); //防止当前页小于1 this.currentPage = Math.max(this.currentPage, 1); //防止当前页大于总的页数 this.currentPage = Math.min(this.totalPage, this.currentPage); //设置上一页，上一页不能小于1 this.prePage = Math.max(this.currentPage-1, 1); //设置下一页，下一页不能大于总页数 this.nextPage = Math.min(this.currentPage+1, this.totalPage); /** * ceil public static double ceil(double a) 返回最小的（最接近负无穷大） double 值，该值大于等于参数，并等于某个整数。特殊情况如下： 如果参数值已经等于某个整数，那么结果与该参数相同。 如果参数为 NaN、无穷大、正 0 或负 0，那么结果与参数相同。 如果参数值小于 0，但是大于 -1.0，那么结果为负 0。 注意， Math.ceil(x) 的值与 -Math.floor(-x) 的值完全相同。 参数： a - 一个值。 返回： 最小（最接近负无穷大）浮点值，该值大于等于该参数，并等于某个整数。 */ } public PageBeanUtils(int prePage, int nextPage, int firstPage, int lastPage, int currentPage, int totalPage, int pageSize, int totalData, List pageData) { super(); this.prePage = prePage; this.nextPage = nextPage; this.firstPage = firstPage; this.lastPage = lastPage; this.currentPage = currentPage; this.totalPage = totalPage; this.pageSize = pageSize; this.totalData = totalData; this.pageData = pageData; } public int getPrePage() { return prePage; } public void setPrePage(int prePage) { this.prePage = prePage; } public int getNextPage() { return nextPage; } public void setNextPage(int nextPage) { this.nextPage = nextPage; } public int getFirstPage() { return firstPage; } public void setFirstPage(int firstPage) { this.firstPage = firstPage; } public int getLastPage() { return lastPage; } public void setLastPage(int lastPage) { this.lastPage = lastPage; } public int getCurrentPage() { return currentPage; } public void setCurrentPage(int currentPage) { this.currentPage = currentPage; } public int getTotalPage() { return totalPage; } public void setTotalPage(int totalPage) { this.totalPage = totalPage; } public int getPageSize() { return pageSize; } public void setPageSize(int pageSize) { this.pageSize = pageSize; } public int getTotalData() { return totalData; } public void setTotalData(int totalData) { this.totalData = totalData; } public List getPageData() { return pageData; } public void setPageData(List pageData) { this.pageData = pageData; } /* * * * totalPage = (totalData+pageSize-1)/pageSize; * * * */ }

 package com.ambow.dao; import java.util.List; import com.ambow.pojo.Good; public interface IGoodDao { //增删改查 public void add(Good good); public void delete(Good good); public void update(Good good); public void query(Good good); public Good queryOne(Good good); public List queryMore(Good good); public List queryByName(String name);//根据商家名称进行模糊查询 //条件分页查询 public List queryByName(String name,int currentPage,int pageSize); //获取满足某个条件的总记录数 public int getTotalNum(String name); }

 package com.ambow.dao.impl; import java.sql.Connection; import java.sql.PreparedStatement; import java.sql.ResultSet; import java.sql.SQLException; import java.util.ArrayList; import java.util.List; import com.ambow.dao.IGoodDao; import com.ambow.pojo.Good; import com.ambow.utils.DBUtils; public class GoodDaoImpl implements IGoodDao { DBUtils db = new DBUtils(); @Override public void add(Good good) { Connection conn = null; PreparedStatement pstmt = null; String sql = "insert into good (name,address,tel,dishes) values (?,?,?,?)"; try { conn = DBUtils.getConnection(); pstmt = conn.prepareStatement(sql); pstmt.setString(1, good.getName()); pstmt.setString(2, good.getAddress()); pstmt.setString(3, good.getTel()); pstmt.setString(4, good.getDishes()); int isOk = pstmt.executeUpdate(); //System.out.println("add-----"+isOk); } catch (SQLException e) { e.printStackTrace(); } } @Override public void delete(Good good) { Connection conn = null; PreparedStatement pstmt = null; String sql = "delete from good where id = ?"; try { conn = DBUtils.getConnection(); pstmt = conn.prepareStatement(sql); pstmt.setInt(1, good.getId()); int isOk = pstmt.executeUpdate(); System.out.println("delete-----"+isOk); } catch (SQLException e) { e.printStackTrace(); } } @Override public void update(Good good) { Connection conn = null; PreparedStatement pstmt = null; String sql = "update good set name=?,address=?,tel=?,dishes=? where id=?"; try { conn = DBUtils.getConnection(); pstmt = conn.prepareStatement(sql); pstmt.setString(1, good.getName()); pstmt.setString(2, good.getAddress()); pstmt.setString(3, good.getTel()); pstmt.setString(4, good.getDishes()); pstmt.setInt(5,good.getId()); int isOk = pstmt.executeUpdate(); } catch (SQLException e) { e.printStackTrace(); } } @Override public void query(Good good) { // TODO Auto-generated method stub } @Override public Good queryOne(Good good) { Connection conn = null; PreparedStatement pstmt = null; ResultSet rs = null; String sql = "select * from good where id = ?"; Good gd = null; try { conn = DBUtils.getConnection(); pstmt = conn.prepareStatement(sql); pstmt.setInt(1, good.getId()); rs = pstmt.executeQuery(); while(rs.next()){ gd = new Good(rs.getInt(1),rs.getString(2),rs.getString(3), rs.getString(4),rs.getString(5)); } } catch (SQLException e) { e.printStackTrace(); } return gd; } @Override public List queryMore(Good good) { // TODO Auto-generated method stub return null; } @Override public List queryByName(String name) { Connection conn = null; PreparedStatement pstmt = null; ResultSet rs = null; String sql = "select * from good where name like ?"; List goodList = new ArrayList(); try { conn = DBUtils.getConnection(); pstmt = conn.prepareStatement(sql); pstmt.setString(1, "%"+name+"%"); rs = pstmt.executeQuery(); while(rs.next()){ goodList.add(new Good(rs.getInt(1),rs.getString(2),rs.getString(3), rs.getString(4),rs.getString(5))); } } catch (SQLException e) { e.printStackTrace(); } return goodList; } @Override public List queryByName(String name, int currentPage, int pageSize) { Connection conn = null; PreparedStatement pstmt = null; ResultSet rs = null; String sql = "select * from good where name like ? limit ?,?"; List goodList = new ArrayList(); try { conn = DBUtils.getConnection(); pstmt = conn.prepareStatement(sql); pstmt.setString(1, "%"+name+"%"); pstmt.setInt(2,(currentPage-1)*pageSize); pstmt.setInt(3,pageSize); rs = pstmt.executeQuery(); while(rs.next()){ goodList.add(new Good(rs.getInt(1),rs.getString(2),rs.getString(3), rs.getString(4),rs.getString(5))); } } catch (SQLException e) { e.printStackTrace(); } return goodList; } @Override public int getTotalNum(String name) { Connection conn = null; PreparedStatement pstmt = null; ResultSet rs = null; String sql = "select count(id) from good where name like ?"; int total = 0; try { conn = DBUtils.getConnection(); pstmt = conn.prepareStatement(sql); pstmt.setString(1, "%"+name+"%"); rs = pstmt.executeQuery(); while(rs.next()){ total = rs.getInt(1); } } catch (SQLException e) { e.printStackTrace(); } return total; } }

 package com.ambow.servlet; import java.io.IOException; import java.util.List; import javax.servlet.ServletException; import javax.servlet.annotation.WebServlet; import javax.servlet.http.HttpServlet; import javax.servlet.http.HttpServletRequest; import javax.servlet.http.HttpServletResponse; import com.ambow.dao.IGoodDao; import com.ambow.dao.impl.GoodDaoImpl; import com.ambow.pojo.Good; import com.ambow.utils.PageBeanUtils; @WebServlet("/QueryServlet") public class QueryServlet extends HttpServlet { private static final long serialVersionUID = 1L; private IGoodDao goodDao = new GoodDaoImpl(); public QueryServlet() { super(); } protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException { doPost(request,response); } protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException { request.setCharacterEncoding("utf-8"); response.setCharacterEncoding("utf-8"); String keywords = request.getParameter("kw"); String method = request.getParameter("method"); if("add".equals(method)){ String name = request.getParameter("name"); String address = request.getParameter("address"); String tel = request.getParameter("tel"); String dishes = request.getParameter("dishes"); Good good = new Good(0,name,address,tel,dishes); goodDao.add(good); //调用dao的查询方法，返回一个List List goods = goodDao.queryByName(keywords); request.setAttribute("list", goods); request.getRequestDispatcher("goods.jsp").forward(request, response); }else if("search".equals(method)){ if(null==keywords) { keywords=""; } int currentPage = 1; try { currentPage=Integer.parseInt(request.getParameter("curPage")); if(currentPage<=0) { currentPage = 1; } }catch(Exception e) { currentPage = 1; } int pageSize=10; int totalData = goodDao.getTotalNum(keywords); int totalPage = (int)Math.ceil((double)totalData/pageSize); if(currentPage>totalPage){ currentPage = totalPage; } List goods = goodDao.queryByName(keywords,currentPage,pageSize); PageBeanUtils pg = new PageBeanUtils(currentPage,pageSize,totalData); pg.setPageData(goods); request.setAttribute("pg", pg); request.getRequestDispatcher("good2.jsp").forward(request, response); }else if("delete".equals(method)){ System.out.println(keywords); //实现删除 String id = request.getParameter("id"); Good good = new Good(); good.setId(Integer.valueOf(id)); goodDao.delete(good); //调用dao的查询方法，返回一个List List goods = goodDao.queryByName(keywords); request.setAttribute("list", goods); request.getRequestDispatcher("goods.jsp").forward(request, response); }else if("queryById".equals(method)){ //查询一个 String id = request.getParameter("id"); Good good = new Good(); good.setId(Integer.valueOf(id)); good = goodDao.queryOne(good); //调用dao的查询方法，返回一个good request.setAttribute("good", good); request.getRequestDispatcher("update.jsp").forward(request, response); }else if("update".equals(method)){ String id = request.getParameter("id"); String name = request.getParameter("name"); String address = request.getParameter("address"); String tel = request.getParameter("tel"); String dishes = request.getParameter("dishes"); Good good = new Good(Integer.valueOf(id),name,address,tel,dishes); goodDao.update(good); //调用dao的查询方法，返回一个List List goods = goodDao.queryByName(keywords); request.setAttribute("list", goods); request.getRequestDispatcher("goods.jsp").forward(request, response); }else{ //调用dao的查询方法，返回一个List List goods = goodDao.queryByName(keywords); request.setAttribute("list", goods); request.getRequestDispatcher("goods.jsp").forward(request, response); } } }

 <%@ page language="java" contentType="text/html; charset=utf-8" pageEncoding="utf-8" import="java.util.ArrayList,com.ambow.pojo.Good, com.ambow.pojo.User,com.ambow.utils.PageBeanUtils"%><%@ taglib prefix="c" uri="http://java.sun.com/jsp/jstl/core" %>   
 添加商家 
 
商家店名
商家地址
商家电话
经营菜品
编辑
${g.name}
${g.address}
${g.tel}
${g.dishes}
修改
删除
首页上一页下一页尾页 当前第${pg.currentPage}页/共${pg.totalPage}页 每页显示${pg.pageSize}条