图书借阅系统简易异步分页源码

分页可以大大的减轻服务器的压力 它一次性只加载部分数据 也增强了用户的体验性 可读性

首先我们需要一个page工具类

package com.shenwang.booksInfoManager.utils;

import java.util.ArrayList;
import java.util.List;

public class Page<T> {
    /**
     * 每页总数
     */
    private int pageSize;
    /**
     * 数据总数(此表中总共有多少条数据)
     */
    private int count;
    /**
     * 每页第一条数据索引
     */
    private int startIndex;
    /**
     * 每页最后一条数据索引
     */
    private int endIndex;
    /**
     * 当前页数
     */
    private int currentPage;
    /**
     * 可点击的开始页
     */
    private int start;
    /**
     * 可点击的最后一页
     */
    private int end;
    /**
     * 总页数
     */
    private int totalPage;
    /**
     * 用于存储每页数据的集合
     */
    private List<T> list=new ArrayList<T>();

    /**
     * 当前页数   每页多少条数据   数据总数
     * @param currentPage
     * @param pageSize
     * @param count
     */
    public Page(int currentPage,int pageSize,int count){
        this.currentPage=currentPage;
        this.pageSize=pageSize;
        this.count=count;
        //求总页数
        if (count%pageSize==0) {
            this.totalPage = count / pageSize;
        }
        else {
            this.totalPage = count / pageSize + 1;
        }

        //每一页的第一条数据的索引
        this.startIndex=(currentPage-1)*pageSize;

        //每页的最后一条数据
        //如果当前页是最后一页
        if (currentPage==totalPage) {
            this.endIndex = count - 1;
        }
        else {
            this.endIndex = startIndex + pageSize - 1;
        }

        //选项卡的启始页和最后一页默认值为1-5
        this.start=1;
        this.end=5;
        if (totalPage<=5) {
            this.end = totalPage;
        }
        else{
            this.start=currentPage-2;
            this.end=currentPage+2;
            if (this.start<=0){
                    this.start=1;
                    this.end=5;
            }
            if (this.end>totalPage){
                this.end=totalPage;
                this.start=end-4;
            }
        }
    }

    public int getPageSize() {
        return pageSize;
    }

    public void setPageSize(int pageSize) {
        this.pageSize = pageSize;
    }

    public int getCount() {
        return count;
    }

    public void setCount(int count) {
        this.count = count;
    }

    public int getStartIndex() {
        return startIndex;
    }

    public void setStartIndex(int startIndex) {
        this.startIndex = startIndex;
    }

    public int getEndIndex() {
        return endIndex;
    }

    public void setEndIndex(int endIndex) {
        this.endIndex = endIndex;
    }

    public int getCurrentPage() {
        return currentPage;
    }

    public void setCurrentPage(int currentPage) {
        this.currentPage = currentPage;
    }

    public int getStart() {
        return start;
    }

    public void setStart(int start) {
        this.start = start;
    }

    public int getEnd() {
        return end;
    }

    public void setEnd(int end) {
        this.end = end;
    }

    public int getTotalPage() {
        return totalPage;
    }

    public void setTotalPage(int totalPage) {
        this.totalPage = totalPage;
    }

    public List<T> getList() {
        return list;
    }

    public void setList(List<T> list) {
        this.list = list;
    }
}

然后是dao层

package com.shenwang.booksInfoManager.dao;

import com.mysql.jdbc.StringUtils;
import com.shenwang.booksInfoManager.pojo.BooksInfo;
import com.shenwang.booksInfoManager.utils.DBCPUtils;
import org.apache.commons.dbutils.QueryRunner;
import org.apache.commons.dbutils.handlers.BeanHandler;
import org.apache.commons.dbutils.handlers.BeanListHandler;
import org.apache.commons.dbutils.handlers.ScalarHandler;

import java.util.ArrayList;
import java.util.List;
@SuppressWarnings("all")
/**
 * @author shenwang
 * @version 1.0
 */
public class BooksInfoDaoImpl implements BooksInfoDao {
    /**
     * 实例化queryRunner
     */
    QueryRunner queryRunner=new QueryRunner(DBCPUtils.getDataSource());
    @Override
    public List<BooksInfo> paging(int startIndex, int pageSize, BooksInfo booksInfo) throws Exception {
        //准备sql语句
        String sql="select * from booksInfo where 1=1";
        //实例化list 用于存储参数
        List<Object> list=new ArrayList<Object>();
        //实例化StringBuffer类用于拼接sql语句
        StringBuffer sbSql=new StringBuffer(sql);
        //如果该对象的书籍编号不为空 则给sbSql追加查询条件
        if (!StringUtils.isNullOrEmpty(booksInfo.getBookNumber())){
            sbSql.append(" and bookNumber like ?");
            list.add("%"+booksInfo.getBookNumber()+"%");
        }
        //如果该对象的借出状态不为空 则给sbSql追加查询条件
        if (booksInfo.getBookFlag()!=null&&booksInfo.getBookFlag()!=-1){
            sbSql.append(" and bookFlag=?");
            list.add(booksInfo.getBookFlag());
        }
        //给sql语句添加分页条件 并且将 startIndex pageSize 添加到list中去
        sbSql.append(" limit ?,?");
        list.add(startIndex);
        list.add(pageSize);

        //返回数据集合
        return queryRunner.query(sbSql.toString(),new BeanListHandler<BooksInfo>(BooksInfo.class),list.toArray());
    }

    @Override
    public int getCount() throws Exception {
        String sql="select count(1) from booksInfo";
        return ((Long)queryRunner.query(sql,new ScalarHandler<>(1))).intValue();
    }

    @Override
    public int getCountByNumberAndFlag(BooksInfo booksInfo) throws Exception {
        //准备sql语句
        String sql="select * from booksInfo where 1=1";
        //实例化list 用于存储参数
        List<Object> list=new ArrayList<Object>();
        //实例化StringBuffer类用于拼接sql语句
        StringBuffer sbSql=new StringBuffer(sql);
        //如果该对象的书籍编号不为空 则给sbSql追加查询条件
        if (!StringUtils.isNullOrEmpty(booksInfo.getBookNumber())){
            sbSql.append(" and bookNumber like ?");
            list.add("%"+booksInfo.getBookNumber()+"%");
        }
        //如果该对象的借出状态不为空 则给sbSql追加查询条件
        if (booksInfo.getBookFlag()!=null&&booksInfo.getBookFlag()!=-1){
            sbSql.append(" and bookFlag=?");
            list.add(booksInfo.getBookFlag());
        }
        List<BooksInfo> query = queryRunner.query(sbSql.toString(), new BeanListHandler<BooksInfo>(BooksInfo.class), list.toArray());
        return query.size();
    }

    @Override
    public int updFlagById(Integer bookId) throws Exception {
        String sql="update booksInfo set bookFlag=1 where bookId=?";
        return queryRunner.update(sql,bookId);
    }

    @Override
    public BooksInfo selById(Integer bookId) throws Exception {
        String sql="select * from booksInfo where bookId=?";
        return queryRunner.query(sql, new BeanHandler<BooksInfo>(BooksInfo.class),bookId);
    }
}

再后面是Service层

package com.shenwang.booksInfoManager.service;

import com.shenwang.booksInfoManager.dao.BooksInfoDao;
import com.shenwang.booksInfoManager.dao.BooksInfoDaoImpl;
import com.shenwang.booksInfoManager.pojo.BooksInfo;
import com.shenwang.booksInfoManager.utils.Page;

import java.util.List;

/**
 * @author shenwang
 * @version 1.0
 */
public class BooksInfoServiceImpl implements BooksInfoService {
    /**
     * 实例化 booksInfo Dao层
     */
    BooksInfoDao dao=new BooksInfoDaoImpl();
    @Override
    public Page<BooksInfo> userPaging(int currentPage, int pageSize,BooksInfo booksInfo) {


        int count= 0;
        try {
            //根据条件筛选数据总数量
            count=dao.getCountByNumberAndFlag(booksInfo);

            Page<BooksInfo> page = new Page<>(currentPage, pageSize, count);

            int start=page.getStartIndex();
            int sum=page.getPageSize();

            List<BooksInfo> list = dao.paging(start,sum,booksInfo);

            page.setList(list);

            return page;
        } catch (Exception e) {
            e.printStackTrace();
            return null;
        }
    }

    @Override
    public int getCount(){
        try {
            return dao.getCount();
        } catch (Exception e) {
            e.printStackTrace();
            return 0;
        }
    }

    @Override
    public boolean updFlagById(Integer bookId) {
        try {
           return dao.updFlagById(bookId)>0?true:false;
        } catch (Exception e) {
            e.printStackTrace();
            return false;
        }
    }

    /**
     * 根据书籍编号查询 返回booksInfo
     * @param bookId
     * @return
     * @throws Exception
     */
    @Override
    public BooksInfo selById(Integer bookId) {
        try {
          return dao.selById(bookId);
        } catch (Exception e) {
            e.printStackTrace();
            return null;
        }
    }
}

Servlet层:

package com.shenwang.booksInfoManager.servlet;

import com.fasterxml.jackson.databind.ObjectMapper;
import com.shenwang.booksInfoManager.pojo.BooksInfo;
import com.shenwang.booksInfoManager.service.BooksInfoService;
import com.shenwang.booksInfoManager.service.BooksInfoServiceImpl;
import com.shenwang.booksInfoManager.utils.Page;

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.HashMap;
import java.util.Map;

@WebServlet(name = "BooksInfoServlet",urlPatterns = "/booksInfoServlet")
public class BooksInfoServlet extends HttpServlet {
    /**
     * 实例化服务层
     */
    BooksInfoService service=new BooksInfoServiceImpl();
    @Override
    protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
        this.doGet(request,response);
    }
    @Override
    protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
        //获取方法名
        String function=request.getParameter("function");

        switch (function==null?"":function){
            //调用分页的方法
            case "paging":
                paging(request,response);
                break;
                //查询
            case "queryPaging":
                queryPaging(request,response);
                break;
                //修改
            case "updFlagById":
                updFlagById(request,response);
                break;
            //默认调用分页的方法
            default:
                paging(request,response);
                break;
        }
    }

    /**
     * 分页
     * @param request
     * @param response
     * @throws ServletException
     * @throws IOException
     */
    protected void paging(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {

        //默认为第一页
        String str=request.getParameter("currentPage");
        int currentPage=1;
        //获取当前页数
        if(str!=null) {
            currentPage = Integer.valueOf(str);
        }
        //默认每页2条数据
        int pageSize=2;
        //获取书籍编号
        Object bookNumberStr=request.getSession().getAttribute("bookNumber");
        String bookNumber=null;
        if (bookNumberStr!=null) {
            bookNumber = bookNumberStr.toString();
        }

        //获取书籍状态
        Object bookFlagStr=request.getSession().getAttribute("bookFlag");
        Integer bookFlag=null;
        //如果bookFlagStr不为空则将bookFlagStr赋值给bookFlag
        if (bookFlagStr!=null) {
            bookFlag = Integer.valueOf(bookFlagStr.toString());
        };
        //实例化booksInfo
        BooksInfo booksInfo=new BooksInfo();
        booksInfo.setBookNumber(bookNumber);
        booksInfo.setBookFlag(bookFlag);


        Page<BooksInfo> page = service.userPaging(currentPage, pageSize,booksInfo);
        //设置属性
        request.setAttribute("page",page);

        request.getRequestDispatcher("index.jsp").forward(request,response);
    }

    /**
     * 查询方法
     * @param request
     * @param response
     * @throws ServletException
     * @throws IOException
     */
    protected void queryPaging(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
        //获取书籍编号 并设置未session属性
        String bookNumber=request.getParameter("bookNumber");
        request.getSession().setAttribute("bookNumber",bookNumber);
        //获取书籍状态 且 设置为session属性
        Integer bookFlag=Integer.valueOf(request.getParameter("bookFlag"));
        request.getSession().setAttribute("bookFlag",bookFlag);
        //调用分页方法
        paging(request,response);
    }

    /**
     * 根据id修改书籍借阅状态 并响应给index.jsp
     * @param request
     * @param response
     * @throws ServletException
     * @throws IOException
     */
    protected void updFlagById(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
            //获取参数 书籍编号
            String bookId = request.getParameter("bookId");
            //根据id获取该书
            BooksInfo book = service.selById(Integer.valueOf(bookId));
            //获取该书的借阅状态
            String bookFlag=String.valueOf(book.getBookFlag());
            if (bookFlag.equals("1")) {
                 //响应
                response.getWriter().write("已借阅");
            }
           else {
                //修改书籍状态
                boolean flag = service.updFlagById(Integer.valueOf(bookId));
                //响应
                response.getWriter().write(String.valueOf(flag));
            }
    }
}

jsp界面

<%@ taglib prefix="c" uri="http://java.sun.com/jsp/jstl/core" %>
<%@ page contentType="text/html;charset=UTF-8" language="java" %>
<html>
<head>
    <%--<link rel="stylesheet" href="https://cdn.jsdelivr.net/npm/bootstrap@4.5.0/dist/css/bootstrap.min.css" integrity="sha384-9aIt2nRpC12Uk9gS9baDl411NQApFmC26EwAOH8WgZl5MYYxFfc+NcPb1dKGj7Sk" crossorigin="anonymous">--%>
        <style>
            td{
                text-align: center;
                 150px;
            }
            tr{
                height: 40px;
            }
        </style>
</head>
<body>
<div align="center" id="showDiv">
    <h2>图书管理系统</h2>
    编号<input type="text" name="bookNumber">

    <select name="bookFlag">
        <option value="-1">全部</option>
        <option value="0">未借阅</option>
        <option value="1">已借阅</option>
    </select>
    <input type="button" value="查询" onclick="query()">
    <hr/>
    <table>
        <tr>
            <th>序号</th>
            <th>图书名称</th>
            <th>作者</th>
            <th>出版社</th>
            <th>编号</th>
            <th>操作</th>
        </tr>
        <c:forEach items="${page.list}" var="book">
            <tr>
                <td>${book.bookId}</td>
                <td>${book.bookName}</td>
                <td>${book.bookPublish}</td>
                <td>${book.bookAuthor}</td>
                <td>${book.bookNumber}</td>
                <td>
                    <c:if test="${book.bookFlag==1}">
                        <a href="javaScript:void(1)" id="msgFlag1">已借阅</a>
                    </c:if>
                    <c:if test="${book.bookFlag==0}">
                        <a href="javaScript:void(1)" onclick="updBookFlag(${book.bookId})") id="msgFlag0">借阅</a>
                    </c:if>
                </td>
            </tr>
        </c:forEach>
        <tr>
            <td>
                <input type="button" value="上一页" id="prev" onclick="prev(${page.currentPage})">
                ${page.currentPage}/${page.totalPage}
                <input type="button" value="下一页" id="next" onclick="next(${page.currentPage})">
            </td>
            <td>
                <input type="button" value="首页" onclick="goHeaderPage(${page.start})">
                <input type="button" value="末页" onclick="goTrailerPage(${page.end})">
            </td>
            <td colspan="2">
                第<input type="text" id="pageNumber">页
                <input type="button" value="Go" onclick="goFindPage()">
            </td>
        </tr>
    </table>

</div>
<script src="js/jquery-3.3.1.min.js"></script>
<script>
    //返回上一页方法
    function prev(currentPage){
        //页数等于当前页数减一
        var curPage=currentPage-1;
        //获取第一页
        var start=${page.start}
        //如果当前页减一小于第一页 则设置当前按钮为不可用 并且不执行下面代码
        if(curPage<start){
            $("#prev").attr("disabled","disabled")
            return;
        }
        //发送请求
        $("#showDiv").load("booksInfoServlet",{"function":"paging","currentPage":curPage})
    }
    //去下一页方法
    function next(currentPage){
        //页数等于当前页数加一
        var curPage=currentPage+1;
        //获取最后一页是第几页
        var end=${page.end}
        //如果当前页加一大于最后一页则设置该按钮不可用 并 不执行下面代码
        if(curPage>end){
            $("#next").attr("disabled","disabled")
            return;
        }
        //发送请求
        $("#showDiv").load("booksInfoServlet",{"function":"paging","currentPage":curPage})
    }
    //根据书籍编号及书籍借阅状态分页查询
    function query(){
        //获取用户输入的书籍编号
       var bookNumber = $("input[name='bookNumber']").val();
       //获取用户选择的书籍借阅状态
       var bookFlag = $("select").val();
        //发送请求
       $("#showDiv").load("booksInfoServlet",{"bookNumber":bookNumber,"bookFlag":bookFlag,"currentPage":1,"function":"queryPaging"})
    }
    //去第一页
    function goHeaderPage(start){
        $("#showDiv").load("booksInfoServlet",{"function":"paging","currentPage":start})
    }
    //去尾页
    function goTrailerPage(end){
        $("#showDiv").load("booksInfoServlet",{"function":"paging","currentPage":end})
    }
    //指定去某一页
    function goFindPage(){
        //获取用户输入的页数
        var pageNumber=$("#pageNumber").val()
        //如果用户输入的页数大于总页数则不执行下面代码
        if(pageNumber>${page.end}){
            alert("抱歉 没有这么多页 请重新输入页数")
            return;
        }
        //如果用户输入的页数为负数则不执行下面代码
        else if(pageNumber<${page.start}){
            alert("抱歉 页数不能为负数 请重新输入页数")
            return;
        }
        var reg=/^d$/
        if (!reg.test(pageNumber)) {
            alert("页数必须为数字")
            return;
        }
        //发送异步请求
        $("#showDiv").load("booksInfoServlet",{"function":"paging","currentPage":pageNumber})
    }
    //借阅书籍方法
    function updBookFlag(bookId){
        $.post("booksInfoServlet",{"function":"updFlagById","bookId":bookId},function (data) {
            if (data=="true") {
                alert("借阅成功~")
                $("#msgFlag0").text("已借阅")
            }
            else if (data=="已借阅") {
                alert("该书已被别位小可爱借走 下次记得早点来哟")
            }
            else{
                alert("借阅失败~")
            }
        },"text")
        $("#")
    }
    $("#msgFlag1").click(function () {
        alert("亲 该书已被别位小可爱借走 下次记得早点来哟")
    })
</script>


</body>
</html>


效果截图 该图书借阅系统 实现了分页 多条件查询分页 去首页 去尾页 去指定页 和借阅功能 下面是效果截图: