WEB项目分页的实现【通用】

一.在工具类中封装一个获取路径的方法，用于获取jsp页面的请求路径及相关参数

 1 public static String getPath(HttpServletRequest request) {
 2         String uri = request.getRequestURI();
 3         //获取请求路径/bookstore02/BookServlet
 4 
 5         String queryString = request.getQueryString();
 6         //获取请求参数method=getPage&pageNumber=4
 7 
 8         
 9         String path=uri+"?"+queryString;
10         //拼接字符串
11         
12         //截取字符串
13         if(path.contains("&pageNumber")){
14             path = path.substring(0, path.indexOf("&pageNumber"));
15         }
16         return path;
17     }
18

二.分页的具体实现

1.创建分页实体类（bean）

  1 package com.neuedu.bean;
  2 
  3 import java.util.List;
  4 
  5 public class Page<T> {
  6  
  7     private List<T> list;     //当前页列表数据
  8     private int pageNumber;   //当前页
  9     private int totalRecord;  //总记录数
 10     private int pageSize;     //每页显示几条数据
 11     
 12 //    private int totalPage;    //总页数(需要计算得到)
 13 //    private int index;        //当前页的索引(需要计算得到)
 14     
 15     private String path;
 16     
 17     
 18     public Page() {
 19         super();    
 20     }
 21     
 22     public List<T> getList() {
 23         return list;
 24     }
 25     
 26     public int getPageNumber() {
 27         if(pageNumber<1){
 28             pageNumber=1;
 29         }
 30         if(pageNumber>getTotalPage()){
 31             pageNumber=getTotalPage();
 32         }
 33         return pageNumber;
 34     }
 35     
 36     public int getTotalPage() {
 37         
 38         if(totalRecord%pageSize==0){
 39             return totalRecord/pageSize;
 40         }else{
 41             return (totalRecord/pageSize)+1;
 42         }
 43         
 44     }
 45     
 46     public int getTotalRecord() {
 47         return totalRecord;
 48     }
 49     
 50     public int getPageSize() {
 51         return pageSize;
 52     }
 53     
 54     public int getIndex() {      //分页查询，在数据访问层调用getIndex方法获得索引值
 55         /**
 56          * pageNumber    pageSize    Index
 57          *     1              3           0
 58          *     2              3           3
 59          *     3              3           6
 60          *     
 61          *    index=(pageNumber-1)*pageSize
 62          */
 63         
 64         return (getPageNumber()-1)*getPageSize();
 65         
 66     }
 67     
 68     public void setList(List<T> list) {
 69         this.list = list;
 70     }
 71     
 72     public void setPageNumber(int pageNumber) {
 73         this.pageNumber = pageNumber;
 74     }
 75     
 76     public void setTotalRecord(int totalRecord) {
 77         this.totalRecord = totalRecord;
 78     }
 79     
 80     public void setPageSize(int pageSize) {
 81         this.pageSize = pageSize;
 82     }
 83     
 84     @Override
 85     public String toString() {
 86         return "Page [list=" + list + ", pageNumber=" + pageNumber
 87                 + ",  totalRecord=" + totalRecord
 88                 + ", pageSize=" + pageSize + "]";
 89     }
 90 
 91     public Page(int pageNumber, int totalRecord, int pageSize) {
 92         super();
 93         this.pageNumber = pageNumber;
 94         this.totalRecord = totalRecord;
 95         this.pageSize = pageSize;
 96     }
 97 
 98     public String getPath() {
 99         return path;
100     }
101 
102     public void setPath(String path) {
103         this.path = path;
104     }
105     
106 }

2.创建Dao层

①创建BookDao接口

 1 package com.neuedu.dao;
 2 
 3 import java.util.List;
 4 import com.neuedu.bean.Book;
 5 
 6 public interface BookDao {
 7     
 8     public int getTotalRecord();                                 //获取数据库总记录数
 9     public List<Book> getBookList(int index, int pageSize);      //得到请求页的数据列表
10 
11 }

②创建BookDao接口的实现类BookDaoImpl

 1 package com.neuedu.dao.impl;
 2 
 3 import java.sql.Connection;
 4 import java.sql.PreparedStatement;
 5 import java.sql.ResultSet;
 6 import java.util.List;
 7 import com.neuedu.utils.JDBCUtils;
 8 import java.sql.Connection;
 9 import java.sql.PreparedStatement;
10 import java.sql.ResultSet;
11 import java.util.ArrayList;
12 import com.neuedu.bean.Book;
13 import com.neuedu.dao.BookDao;
14 
15 public class BookDaoImpl implements BookDao{
16 
17     private Connection conn=null;
18     private PreparedStatement ps=null;
19     private ResultSet rs=null;
20     
21 
22     //查询数据库中总记录数
23     public int getTotalRecord() {
24         ResultSet rs =null;
25         int totalRecord=0;
26         try {
27             conn= JDBCUtils.getConnection();
28             String sql="select count(*) totalRecord from book";
29             ps=conn.prepareStatement(sql);
30             rs = ps.executeQuery();
31             
32             if(rs.next()){
33                 totalRecord = rs.getInt("totalRecord");
34             }
35             
36         } catch (Exception e) {
37             e.printStackTrace();
38         }finally{
39             JDBCUtils.close(conn, ps, rs);
40         }
41         
42         return totalRecord;
43         
44     }
45 
46     //访问数据库，通过limit (当前页的索引，每页显示几条数据) 实现分页查询，得到请求页的数据列表
47     public List<Book> getBookList(int index, int pageSize) {
48         ResultSet rs =null;
49         int totalRecord=0;
50         List<Book> list=new ArrayList<Book>();
51         try {
52             conn= JDBCUtils.getConnection();
53             String sql="select * from book limit ?,?";
54             ps=conn.prepareStatement(sql);
55             ps.setInt(1, index);
56             ps.setInt(2, pageSize);
57             rs = ps.executeQuery();
58             while(rs.next()){
59                 int id = rs.getInt("id");
60                 String bookName = rs.getString("book_name");
61                 String author = rs.getString("author");
62                 int price = rs.getInt("price");
63                 int sales = rs.getInt("sales");
64                 int stock = rs.getInt("stock");
65                 String imgPath = rs.getString("img_path");
66                 
67                 list.add(new Book(id, bookName, author, price, sales, stock, imgPath));
68             }
69             
70         } catch (Exception e) {
71             e.printStackTrace();
72         }finally{
73             JDBCUtils.close(conn, ps, rs);
74         }
75         return list;
76     }
77 }

3.创建service层

获取当前页的数据列表

 1 package com.neuedu.service;
 2 
 3 import java.util.List;
 4 import com.neuedu.bean.Book;
 5 import com.neuedu.bean.Page;
 6 import com.neuedu.dao.impl.BookDaoImpl;
 7 
 8 public class BookService {
 9 
10     private BookDaoImpl dao =new BookDaoImpl();
11     
12     
13     public Page<Book> getPage(int pageSize,String pageNumber){
14         int pageNum=1;
15         Page<Book> page=null;
16         try{
17             pageNum=Integer.parseInt(pageNumber);
18         }catch(Exception e) {    
19         }    
20             //1.获取总记录数
21             int totalRecord=dao.getTotalRecord();
22             //2.封装page对象
23             page=new Page<>(pageNum,totalRecord,pageSize);
24             //3.查询当前页对应的数据列表并设置到page对象中
25             List<Book> list=dao.getBookList(page.getIndex(),pageSize);
26             page.setList(list);
27         
28         return page;
29     }
30     
31     
32 }

4.创建servlet层

 1 package com.neuedu.web;
 2 
 3 import java.io.IOException;
 4 import java.util.List;
 5 
 6 import javax.servlet.ServletException;
 7 import javax.servlet.http.HttpServlet;
 8 import javax.servlet.http.HttpServletRequest;
 9 import javax.servlet.http.HttpServletResponse;
10 
11 import com.neuedu.bean.Book;
12 import com.neuedu.bean.Page;
13 import com.neuedu.service.BookService;
14 import com.neuedu.utils.WEBUtils;
15 
16 
17 public class BookServlet extends BaseServlet {
18     private static final long serialVersionUID = 1L;
19 
20     private BookService service=new BookService();
21     
22     public void getPage(HttpServletRequest request, HttpServletResponse response){
23         
24         String path=WEBUtils.getPath(request);
25         String pageNumber = request.getParameter("pageNumber");
26         Page<Book> page = service.getPage(pageSize, pageNumber);
27         page.setPath(path);
28         
29         request.setAttribute("page", page);
30         try {
31             request.getRequestDispatcher("/pages/manager/book_manager.jsp").forward(request, response);
32         } catch (Exception e) {
33             e.printStackTrace();
34         }
35     }
36  }   
37

三.前台页面的实现

 1 <%@ page language="java" contentType="text/html; charset=UTF-8"
 2     pageEncoding="UTF-8"%>
 3 <%@taglib prefix="c" uri="http://java.sun.com/jsp/jstl/core"  %>    
 4 <!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" "http://www.w3.org/TR/html4/loose.dtd">
 5 <div id="page_nav">
 6     <a href="${page.path}&pageNumber=1">首页</a>
 7     <c:if test="${page.pageNumber>1}">
 8         <a href="${page.path}&pageNumber=${page.pageNumber-1}">上一页</a>
 9     </c:if>
10 
11     <c:choose>
12         <c:when test="${page.totalPage<=5}">
13             <c:set var="begin" value="1"></c:set>
14             <c:set var="end" value="${page.totalPage}"></c:set>
15         </c:when>
16         <c:when test="${page.pageNumber<=3}">
17             <c:set var="begin" value="1"></c:set>
18             <c:set var="end" value="5"></c:set>
19         </c:when>
20         <c:when test="${page.pageNumber>3}">
21             <c:set var="begin" value="${page.pageNumber-2 }"></c:set>
22             <c:set var="end" value="${page.pageNumber+2 }"></c:set>
23             <c:if test="${page.pageNumber+2>=page.totalPage}">
24                 <c:set var="end" value="${page.totalPage}"></c:set>
25                 <c:set var="begin" value="${page.totalPage-4}"></c:set>
26             </c:if>
27         </c:when>
28     </c:choose>
29     
30     <c:forEach begin="${begin}" end="${end}" var="index">
31         <c:if test="${page.pageNumber==index}">
32             <a href="${page.path}&pageNumber=${page.pageNumber}">【${index}】</a>
33         </c:if>
34         <c:if test="${page.pageNumber!=index}">
35             <a href="${page.path}&pageNumber=${index}">${index}</a>
36         </c:if>
37     </c:forEach>
38 
39     <c:if test="${page.pageNumber<page.totalPage}">
40         <a href="${page.path}&pageNumber=${page.pageNumber+1}">下一页</a>
41     </c:if>
42     
43     <a href="${page.path}&pageNumber=${page.totalPage}">末页</a>
44     共${page.totalPage}页，${page.totalRecord}条记录到第<input value="${page.pageNumber}" name = "pn" id ="pn_input"/>页
45     <input id="btn" type="button" value="确定"/>
46     
47     <script type="text/javascript">
48         $(function(){
49             $("#btn").click(function(){
50                 var pageNum=$("#pn_input").val();
51                 window.location="${page.path}&pageNumber="+pageNum;
52             });
53         });
54     </script>
55     
56 </div>
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原文地址：https://www.cnblogs.com/double-s/p/8119790.html