Web分页显示数据

这个是基于MVC框架写的。

首先对数据库进行封装处理

public class DataBase {
    static String driver = "com.mysql.jdbc.Driver";
    static String url = "jdbc:mysql://127.0.0.1:3306/xscjgl2?useUnicode=true&characterEncoding=utf8";
    static String user = "root";
    static String password = "root";
    static String maxsql = null;
    static Connection con = null;
    static int tt ;
    static Statement sta = null;
    static ResultSet res = null;
    //连接数据库
    static public Connection lianjie(){
        try {
            Class.forName(driver);
            con = DriverManager.getConnection(url, user, password);                 
        } catch (ClassNotFoundException e) {
            e.printStackTrace();
        } catch (SQLException e) {
            e.printStackTrace();
        }       
        return con;     
    }
//查询
    public ResultSet sel(String sql){
        con = lianjie();
        try {
            sta = con.createStatement();
            res = sta.executeQuery(sql);
        } catch (SQLException e) {
            e.printStackTrace();
        }   
        return res;     
    }

数据库的数据

dao层处理

在dao层里定义分页的方法

package com.dao;

import java.util.List;

import com.model.Page;

public interface Fy {
    //计算出Page属性的值
    Page page();
    //按照分页查询全部
    List selectAll(int offsetone,int slide);

}

daoImpl实现层里处理数据库得到的数据

package com.dao.iml;

import java.sql.ResultSet;
import java.sql.SQLException;
import java.util.ArrayList;
import java.util.List;

import com.dao.Fy;
import com.database.DBcon01;
import com.model.Page;
import com.model.Student;

public class FyImpl implements Fy {
    DBcon01 db = new DBcon01();

    @Override
    // 可以查到总条数，根据总条数和每页显示计算出总页数（总条数+每页显示数-1）/每页显示数
    public Page page() {
        Page p = null;
        // 查询总条数
        String sql = "select COUNT(*) from student";
        ResultSet res = db.sel(sql) ;  //sel是DataBase.java的一个方法
        // 定义总页数
        int pc = 0;
        // 定义总条数
        int z = 0;
        try {
            while (res.next()) {
                p = new Page();
                z = res.getInt(1);
                p.setCount(z);
            }
            // 计算出总页数
            pc = (z + p.getSlide() - 1) / p.getSlide();
            p.setPageCount(pc);
            /*
 * //判断如果有余数，那么总页数＋1 if(z%p.getSlide()==0){ pc =z/p.getSlide();
 * }else{ pc =z/p.getSlide()+1; }
 */

        } catch (SQLException e) {
            e.printStackTrace();
        }
        return p;
    }
    @Override
    //得到每页要显示的数据
    public List selectAll(int offsetone, int slide) {
        List list = new ArrayList();
        Student stu = null;
        /* //select字段列表 from数据源 limit [start,]length;
 start表示从第几行记录开始检索，length表示检索多少行记录。表中第一行记录的start值为0*/
        //查询某几行记录
        String sql = "select * from student limit " + offsetone + "," + slide
                + "";
        ResultSet res = db.sel(sql);
        try {
            while (res.next()) {
                int id = res.getInt(1);
                String stuName = res.getString(2);
                String stuSex = res.getString(3);
                String stuAge = res.getString(4);
                //通过有参的构造方法创建Student对象
                stu = new Student(id, stuName, stuSex, stuAge);
                //把Student对象增加到list集合
                list.add(stu);
            }
        } catch (SQLException e) {
            // TODO Auto-generated catch block
            e.printStackTrace();
        }

        return list;
    }

}

service层处理

在service层里，这个比较简单，service层只是跳转一下。

package com.service;

import java.util.List;

import com.model.Page;

public interface FyService {
    //计算出Page属性的值
    Page page();
    //按照分页查询全部
    List selectAll(int offsetone,int slide);
}

在serviceImpl层的实现层里

package com.service.impl;

import java.util.List;

import com.dao.Fy;
import com.dao.iml.FyImpl;
import com.model.Page;
import com.service.FyService;

public class FyServiceImpl implements FyService{
        Fy f = new FyImpl();
    @Override
    public Page page() {
        return f.page();
    }
    @Override
    public List selectAll(int offsetone, int slide) {
        return f.selectAll(offsetone, slide);
    }
}

在servlet里

package com.servlet;

import java.io.IOException;
import java.util.List;

import javax.servlet.ServletException;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;

import com.model.Page;
import com.model.Student;
import com.service.FyService;
import com.service.impl.FyServiceImpl;

public class FyServlet extends HttpServlet {

    public void doGet(HttpServletRequest request, HttpServletResponse response)
            throws ServletException, IOException {
        //从页面获取pagenow
         int pagenow = Integer.parseInt(request.getParameter("pagenow"));

        FyService fs = new FyServiceImpl();
        Page page =fs.page();
        //通过pagenow计算出offsetone
        page.setOffsetone((pagenow-1)*page.getSlide());
        //通过调取FyServiceImpl中的selectAll(page.getOffsetone(), page.getSlide())，返回每页查询的数据集合
        List<Student> list= fs.selectAll(page.getOffsetone(), page.getSlide());

        request.setAttribute("list", list);
        request.getSession().setAttribute("page1", page);
        request.getRequestDispatcher("/fy/StuAll.jsp").forward(request, response);

    }

    public void doPost(HttpServletRequest request, HttpServletResponse response)
            throws ServletException, IOException {


    }

}

在model层里写一个Page的类

package com.model;

/*
 * @封装分页的共同属性
 * 
 */

public class Page {

    private int count;//得到数据的总条数
    private int  slide=4; //每页显示的4条
    private int offsetone;//每页的第一条
    private int pageCount;// 总页数
    public int getCount() {
        return count;
    }
    public void setCount(int count) {
        this.count = count;
    }
    public int getSlide() {
        return slide;
    }
    public void setSlide(int slide) {
        this.slide = slide;
    }
    public int getOffsetone() {
        return offsetone;
    }
    public void setOffsetone(int offsetone) {
        this.offsetone = offsetone;
    }
    public int getPageCount() {
        return pageCount;
    }
    public void setPageCount(int pageCount) {
        this.pageCount = pageCount;
    }

显示的界面

写一个跳转的界面

pagenow给servlet传一个页面参数

 <body>
    <a href="Paging?pagenow=1">查找所有</a>
  </body>

显示数据的StuAll.jsp页面

//导入JSTL标签
<%@ taglib uri="http://java.sun.com/jsp/jstl/core" prefix="c"%>
<body>
    <%
 List list = (List) request.getAttribute("list");
 int size = list.size();
 %>

    <c:choose>
        <c:when test="<%=size == 0%>">
        对不起，您没有查到数据。。。。。

        </c:when>
        <c:otherwise>
            <table>
                <tr>
                    <td>学号</td>
                    <td>姓名</td>
                    <td>年龄</td>
                    <td>性别</td>
                    <td>修改</td>
                    <td>删除</td>
                </tr>
                <c:forEach items="${list}" var="list1">
                    <tr>
                        <td>${list1.stuId}</td>
                        <td>${list1.stuName}</td>
                        <td>${list1.stuSex}</td>
                        <td>${list1.stuAge}</td>
                        <td><a href="">修改</a></td>
                        <td><a href="">删除</a></td>
                    </tr>
                </c:forEach>
            </table>
            <br>
            <br>


        </c:otherwise>
    </c:choose>

    <ul class="pagination pagination-lg">

        <%
 int offset = new Integer(request.getParameter("pagenow"));
 Page pb = (Page) session.getAttribute("page1");

 out.println("<li ><a href=FyServlet?pagenow=1" + ">首页</a></li>");
 %>
        <%
 if (offset > 1) {
 out.println("<li ><a href=FyServlet?pagenow=" + (offset - 1)
 + ">&laquo;</a></li>");
 } else {
 out.println("<li class='disabled'><a>&laquo;</a></li>");
 }
 %>
        <%
 for (int i = 1; i <= pb.getPageCount(); i++) {
 out.print("<li><a href=FyServlet?pagenow=" + i + ">-" + i
 + "-</a></li>");

 }
 %>
        <%
 if (offset < pb.getPageCount()) {
 out.println("<li><a href=FyServlet?pagenow=" + (offset + 1)
 + ">&raquo</a></li>");
 } else {
 out.println("<li class='disabled'><a>&raquo</a></li>");
 }
 %>
        <%
 out.println("<li><a href=FyServlet?pagenow=" + pb.getPageCount()
 + ">尾页</a></li>");
 %>
    </ul>
</body>

首先对数据库进行封装处理

dao层处理

service层处理

在servlet里

在model层里写一个Page的类

显示的界面

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