如何用jsp+mysql实现网页的分页查询

一、实现分页查询的核心sql语句

（1）查询数据库的记录总数的sql语句：

select count(*) from +（表名）;

（2）每次查询的记录数的sql语句：

其中：0是搜索的索引，2是每次查找的条数。

select * from 表名 limit 0,2;

二、代码实现

在上一篇中，我已经介绍了DBconnection类和Author对象类，前者用于获取数据库连接，后者用于表示作者对象。这两个类的代码点击连接查看。点击链接以查看 DBconnection 类和 Author 对象类

（1）登录页面：index.jsp。

    用户列表分页查询

（2）显示页面：userlistpage.jsp。

  
    
编号
    
名称
    
价格
    
数量
    
日期
    
风格
  
    
    
${author.id}
    
${author.name }
    
${author.price }
    
${author.num }
    
${author.dates}
    
${author.style}
  
  
0}">
            <c:if test="${pageBean.currentPage       首页      上一页      下一页      尾页                   1 && pageBean.currentPage        首页      上一页      下一页      尾页                = pageBean.totalPage}">      首页      上一页     下一页     尾页     

（3）功能实现：AuthorDao.java。

package com.dao;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.entity.Author;public class AuthorDao {         public  Author check(String username ,int  password ) {                  Author obj = null ;         try {            DBConnection db = new DBConnection();            //获取数据库连接            Connection conn = db.getConn();                        String sql="select *from furnitures where name = ? and id = ?";                        PreparedStatement ps=conn.prepareStatement(sql);            //设置用户名和密码作为参数放入sql语句            ps.setString(1,username);            ps.setInt(2,password);            //执行查询语句            ResultSet rs = ps.executeQuery();            //用户名和密码正确，查到数据  欧式风格  茶几            if(rs.next()) {                obj = new Author();                obj.setId(rs.getInt(1));                obj.setName(rs.getString(2));                obj.setPrice(rs.getInt(3));                obj.setNum(rs.getInt(4));                obj.setDates(rs.getString(5));                obj.setStyle(rs.getString(6));            }        } catch (SQLException e) {            // TODO Auto-generated catch block            e.printStackTrace();        }         return obj;     }     /**      * 用户列表信息查询      * @return      */     public List queryAuthorList(){         Author obj = null ;         List list = new ArrayList();         try {            DBConnection db = new DBConnection();            //获取数据库连接            Connection conn = db.getConn();                        String sql="select *from furnitures";                        PreparedStatement ps=conn.prepareStatement(sql);                //执行查询语句            ResultSet rs = ps.executeQuery();            //用户名和密码正确，查到数据  欧式风格  茶几            //循环遍历获取用户信息            while(rs.next()) {                                obj = new Author();                obj.setId(rs.getInt(1));                obj.setName(rs.getString(2));                obj.setPrice(rs.getInt(3));                obj.setNum(rs.getInt(4));                obj.setDates(rs.getString(5));                obj.setStyle(rs.getString(6));                //将对象加入list里边                list.add(obj);            }        } catch (SQLException e) {            // TODO Auto-generated catch block            e.printStackTrace();        }         return list;     }               /**      * 查询用户表总记录数      * @return      */     public int queryUserListCount() {         DBConnection db;        try {             db = new DBConnection();             Connection conn = db.getConn();             String sql = "select count(*) from furnitures";                          PreparedStatement ps = conn.prepareStatement(sql);             ResultSet rs = ps.executeQuery();                                       if(rs.next()) {                 return rs.getInt(1);             }                                  } catch (SQLException e) {            // TODO Auto-generated catch block            e.printStackTrace();        }                 return 0;     }     /**      * 查询用户分页数据      * @param pageIndex数据起始索引      * @param pageSize每页显示条数      * @return      */     public ListqueryUserListPage(int pageIndex,int pageSize){                  Author obj = null;         List list = new ArrayList();                  try {            Connection conn = new DBConnection().getConn();            String sql = "select * from furnitures limit ?,?;";            PreparedStatement ps = conn.prepareStatement(sql);            ps.setObject(1, pageIndex);            ps.setObject(2,pageSize);                        ResultSet rs = ps.executeQuery();            //遍历结果集获取用户列表数据                        while(rs.next()) {                obj = new Author();                                obj.setId(rs.getInt(1));                obj.setName(rs.getString(2));                obj.setPrice(rs.getInt(3));                obj.setNum(rs.getInt(4));                obj.setDates(rs.getString(5));                obj.setStyle(rs.getString(6));                                list.add(obj);            }        } catch (SQLException e) {            // TODO Auto-generated catch block            e.printStackTrace();        }         return list;     }     /**      * 用户新增      * @param obj      */     public void add(Author obj) {                try {                        DBConnection db = new DBConnection();            //获取数据库连接            Connection conn = db.getConn();                        String sql="insert into furnitures values(id,?,?,?,?,?)";                        PreparedStatement ps=conn.prepareStatement(sql);            ps.setObject(1, obj.getName());            ps.setObject(2, obj.getPrice());            ps.setObject(3, obj.getNum());            ps.setObject(4,obj.getDates());            ps.setObject(5, obj.getStyle());                        //执行sql语句           ps.execute();                               } catch (SQLException e) {            // TODO Auto-generated catch block            e.printStackTrace();        }                 }     //删除用户     public void del(int id) {         try {                                DBConnection db = new DBConnection();                //获取数据库连接                Connection conn = db.getConn();                                String sql="delete from furnitures where id = ?";                                PreparedStatement ps=conn.prepareStatement(sql);                                ps.setObject(1, id);                                //执行sql语句               ps.execute();                                           } catch (SQLException e) {                // TODO Auto-generated catch block                e.printStackTrace();            }                     }    }

（4）交互层：AuthorListPageServlet.java。

package com.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.dao.AuthorDao;import com.entity.Author;import com.util.PageBean;/** * Servlet implementation class AuthorListPageServlet */@WebServlet("/AuthorListPageServlet")public class AuthorListPageServlet extends HttpServlet {    private static final long serialVersionUID = 1L;           /**     * @see HttpServlet#HttpServlet()     */    public AuthorListPageServlet() {        super();        // TODO Auto-generated constructor stub    }    /**     * @see HttpServlet#doGet(HttpServletRequest request, HttpServletResponse response)     */    protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {        // TODO Auto-generated method stub        int pageSize = 2;        AuthorDao ad = new AuthorDao();        //总记录数        int record = ad.queryUserListCount();        //接收页面传入的页码        String strPage = request.getParameter("currPage");        int currPage = 1;//默认第一页        if(strPage != null) {            currPage = Integer.parseInt(strPage);            }                PageBean pb = new PageBean(currPage,pageSize,record);        //查询某一页的结果集        List list = ad.queryUserListPage(pb.getPageIndex(), pageSize);        pb.setList(list);        request.setAttribute("pageBean", pb);        request.getRequestDispatcher("userlistpage.jsp").forward(request, response);    }    /**     * @see HttpServlet#doPost(HttpServletRequest request, HttpServletResponse response)     */    protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {        // TODO Auto-generated method stub        doGet(request, response);    }}

（5）工具类：PageBean.java。作用是：获取结果集。

package com.util;import java.util.List;public class PageBean{    private int currentPage;//当前页码    private int pageIndex;//数据起始索引    private int pageSize;//每页条数            private int record;//总记录数    private int totalPage;//总页数        private Listlist;//每页显示的结果集    /**     * 构造方法初始化pageIndex和totalPage     * @param currentPage     * @param pageIndex     * @param pageSize     */    public PageBean(int currentPage,int pageSize,int record) {                this.currentPage = currentPage;        this.pageSize = pageSize;        this.record = record;                //总页数        if(record % pageSize == 0) {            //整除，没有多余的页            this.totalPage = record / pageSize;                    }        else {            //有多余的数据，在增加一页            this.totalPage = record / pageSize + 1;        }                //计算数据起始索引pageIndex        if(currentPage  this.totalPage) {            this.currentPage = this.totalPage;        }        this.pageIndex = (this.currentPage -1)*this.pageSize;    }        public int getCurrentPage() {        return currentPage;    }    public void setCurrentPage(int currentPage) {        this.currentPage = currentPage;    }    public int getPageIndex() {        return pageIndex;    }    public void setPageIndex(int pageIndex) {        this.pageIndex = pageIndex;    }    public int getPageSize() {        return pageSize;    }    public void setPageSize(int pageSize) {        this.pageSize = pageSize;    }    public int getRecord() {        return record;    }    public void setRecord(int record) {        this.record = record;    }    public int getTotalPage() {        return totalPage;    }    public void setTotalPage(int totalPage) {        this.totalPage = totalPage;    }    public List getList() {        return list;    }    public void setList(List list) {        this.list = list;    }    }

三、运行结果

（1）首页：

（2）中间页：

（3）尾页：

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