制作分页工具类,实现分页操作JSP+Servlet+数据库

快来打我* 2022-11-07 14:39 251阅读 0赞

# 分页操作 #

基于jsp+Servlet+数据库的分页操作

每页限制显示的条数,显示总页数,总条数.可以看上一页下一页

**操作说明** :需先进入到controller层的接口,将数据查询出来

在放入到session域中,可以转发或重定向到展示数据的页面

使用El表达式取出数据

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先写个制作分页的工具类

## LimitPageUtil分页工具类 ##

import java.util.List;
    
    /** * @program: internetbar_Test * @description: 分页工具类 * @author: 高天乐 * @create: 2021-03-10 14:27 * * 属性:list集合装数据 当前页 每页显示多少条 总条数 总页数 **/
    public class LimitPageUtil<T> { 
        //查询到的数据
        private List<T> list;
        //总条数 totalCount
        private Integer totalCount;
        //当前页数
        private Integer currentPage;
        //每页显示的条数
        public static final Integer ROWS = 10;
        //总页数
        private Integer totalPage;
    
        public List<T> getList() { 
            return list;
        }
    
        public void setList(List<T> list) { 
            this.list = list;
        }
    
        public Integer getTotalCount() { 
            return totalCount;
        }
    
        public void setTotalCount(Integer totalCount) { 
            this.totalCount = totalCount;
        }
    
        public Integer getCurrentPage() { 
            return currentPage;
        }
    
        public void setCurrentPage(Integer currentPage) { 
            this.currentPage = currentPage;
        }
    
        public Integer getTotalPage() { 
            return totalPage;
        }
    
        public void setTotalPage(Integer totalPage) { 
            this.totalPage = totalPage;
        }
    
        /** * 计算页数开始的索引数 * @param currentPage 当前页 * @return */
        public static Integer getIndex(Integer currentPage){ 
            return (currentPage-1)*ROWS;
        }
    
        /** * 计算总页数 * @param totalCount 传入总条数 * @return */
        public static Integer getTotalPage(Integer totalCount){ 
            return totalCount%ROWS==0?totalCount/ROWS:totalCount/ROWS+1;
        }
    }

## Dao层 ##

这里写sql分页的接口

package com.kangye.ibms.dao;
    
    import com.kangye.ibms.entity.User;
    
    import java.util.List;
    
    /** * @program: internetbar * @description: 用户Dao * @author: 高天乐 * @create: 2021-03-06 16:44 **/
    public interface UserDao<T> { 
    
        //查询全部数据
        List<T> allUser(Class<User> c,Object... obj);
    
        //查数据的总共条数
        Integer totalCount();
    }

实现dao层接口

package com.kangye.ibms.dao.impl;
    
    import com.kangye.ibms.dao.UserDao;
    import com.kangye.ibms.entity.User;
    import com.kangye.ibms.utils.DbUtil;
    
    import java.util.Arrays;
    import java.util.List;
    
    /** * @program: internetbar * @description: 用户dao实现 * @author: 高天乐 * @create: 2021-03-06 16:44 **/
    public class UserDaoImpl implements UserDao<User> { 
    
        /** * 查询全部的数据 * @return */
        @Override
        public List<User> allUser(Class<User> c,Object... obj) { 
            //定义sql语句
            String sql = "select * from user limit ?,?";
            return DbUtil.selectList(sql,c,obj); 
            //DbUtil.selectList(sql,c,obj); 查询数据库的操作,可自行引用其他的
        }
    
        /** * 查出总条数 * @return */
        @Override
        public Integer totalCount() { 
            //定义sql语句
            String sql = "select count(*) from user";
            return DbUtil.selectWhere(sql);
        }
    
    }

## Service层 ##

package com.kangye.ibms.service;
    
    import com.kangye.ibms.entity.User;
    import com.kangye.ibms.utils.LimitPageUtil;
    
    import java.util.List;
    
    /** * @program: internetbar * @description: 用户逻辑层 * @author: 高天乐 * @create: 2021-03-06 16:46 **/
    public interface UserService<T> { 
        //查询全部数据
        LimitPageUtil<T> allUser(Class<User> c,Integer currentPage);
    
    }

实现service层 做具体的逻辑

package com.kangye.ibms.service.impl;
    
    import com.kangye.ibms.dao.UserDao;
    import com.kangye.ibms.dao.impl.UserDaoImpl;
    import com.kangye.ibms.entity.User;
    import com.kangye.ibms.service.UserService;
    import com.kangye.ibms.utils.LimitPageUtil;
    
    import java.util.Arrays;
    import java.util.List;
    
    /** * @program: internetbar * @description: 用户逻辑实现 * @author: 高天乐 * @create: 2021-03-06 16:47 **/
    public class UserServiceImpl implements UserService<User> { 
       UserDao<User> userDao = new UserDaoImpl();
        /** * 分页查询数据 * @param c 实体类 * @param currentPage 当前页数 * @return */
        @Override
        public LimitPageUtil<User> allUser(Class<User> c,Integer currentPage) { 
            //创建分页类对象
            LimitPageUtil<User> limit = new LimitPageUtil<>();
            //当前页数
            limit.setCurrentPage(currentPage);
            //查出数据
            List<User> userList = userDao.allUser(c, new Object[]{ LimitPageUtil.getIndex(currentPage), LimitPageUtil.ROWS});
            //添加数据
            limit.setList(userList);
            //查出总条数
            Integer totalCount = userDao.totalCount();
    
            limit.setTotalCount(totalCount);
            //总页数
            limit.setTotalPage(LimitPageUtil.getTotalPage(totalCount));
            return limit;
        }
    
    }

## controller层 ##

接收页面传递过来的数据,拿到数据放入service层

import com.kangye.ibms.dao.UserDao;
    import com.kangye.ibms.dao.impl.UserDaoImpl;
    import com.kangye.ibms.entity.User;
    import com.kangye.ibms.service.UserService;
    import com.kangye.ibms.service.impl.UserServiceImpl;
    import com.kangye.ibms.utils.LimitPageUtil;
    
    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 java.io.IOException;
    import java.util.List;
    
    /** * @program: internetbar_Test * @description: 用户列表 * @author: 高天乐 * @create: 2021-03-09 10:11 **/
    @WebServlet("/userList")
    public class UserListServlet extends HttpServlet { 
        UserService<User> userService = new UserServiceImpl();
        @Override
        protected void doGet(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException { 
            this.doPost(req, resp);
        }
    
        @Override
        protected void doPost(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException { 
            //初始化页面数
            Integer currentPage = 1;
            //前台传入的页面数
            String currentPage1 = req.getParameter("currentPage");
            //判断页面是否传过来页面数
            if(currentPage1 != null){ 
                currentPage = Integer.parseInt(currentPage1);
                //如果传过来的页面数小于1的话,赋值为1
                if (currentPage < 1) { 
                    currentPage = 1;
                }
                //创建dao层对象
                UserDao<User> userDao = new UserDaoImpl();
                //查询总数据的条数
                Integer userDataCount = userDao.totalCount();
                //计算出总页数
                Integer totalPage = LimitPageUtil.getTotalPage(userDataCount);
                //传递进来的页面数大于总页数,赋值为最后一页
                if(currentPage >totalPage){ 
                    currentPage = totalPage;
                }
            }
            LimitPageUtil<User> limit = userService.allUser(User.class,currentPage);
            //将数据放入到session里
            req.getSession().setAttribute("limit",limit);
            //重定向到页面
            resp.sendRedirect("index.jsp");
        }
    }

## JSP页面代码 ##

<%@ page contentType="text/html;charset=utf-8" language="java" %>
    <%@ taglib prefix="c" uri="http://java.sun.com/jsp/jstl/core" %>
    <!DOCTYPE html>
    <html>
    <head>
        <meta charset="UTF-8">
        <title>数据页面</title>
    
    </head>
    <body>
    <table id="data_user" border="1" cellpadding="5px" cellspacing="0px" align="center">
        <caption>用户信息</caption>
        <tr>
            <td><input type="checkbox" name="checkAll" id="checkAll"/></td>
            <td>编号</td>
            <td>姓名</td>
            <td>性别</td>
            <td>年龄</td>
            <td>居住地址</td>
            <td>手机号</td>
            <td>操作</td>
        </tr>
        
        <c:forEach items="${limit.list}" var="user" varStatus="i">
            <tr>
                <td><input type="checkbox" name="checks" value="${user.id}"/></td>
                <td>${i.index+1}</td>
                <td>${user.name}</td>
                <td>${user.sex}</td>
                <td>${user.age}</td>
                <td>石家庄市</td>
                <td>${user.phone}</td>
                <td><a href="javaScript:;">修改</a> <a href="javaScript:;" onclick="del(${user.id})">删除</a></td>
            </tr>
        </c:forEach>
        <tr>
            <td colspan="8">
                <c:if test="${limit.currentPage>1}">
                    <a href="/userList?currentPage=${limit.currentPage-1}">上一页</a>
                </c:if>
                
                当前页:${limit.currentPage}/${limit.totalPage}
    
                <c:if test="${limit.currentPage<limit.totalPage}">
                    <a href="/userList?currentPage=${limit.currentPage+1}">下一页</a>
                </c:if>
    
                总数据:${limit.totalCount}
    
                <a href="/userList?currentPage=1">首页</a>
    
                <a href="/userList?currentPage=${limit.totalPage}">尾页</a>
                <button class="detele">全部删除</button>
                <button class="add">添加</button>
            </td>
        </tr>
    </table>
    </body>
    </html>

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