本文實(shí)例為大家分享了JSP實(shí)現(xiàn)分頁(yè)的具體代碼，供大家參考，具體內(nèi)容如下

咱們?cè)跒g覽網(wǎng)頁(yè)的時(shí)候，當(dāng)一個(gè)頁(yè)面的數(shù)據(jù)不足以展示完全所有的內(nèi)容，一般都涉及到分頁(yè)，下一頁(yè)的功能該怎么實(shí)現(xiàn)呢？首先我們來(lái)分析一下：

那么直接上代碼：

這里需要備注一下，本次的代碼是在對(duì)三層優(yōu)化之后進(jìn)行操作的，所以我先把數(shù)據(jù)訪問(wèn)層的重構(gòu)代碼貼出來(lái)：

package org.ThreeLayer.DButil;import java.sql.Connection;import java.sql.DriverManager;import java.sql.PreparedStatement;import java.sql.ResultSet;import java.sql.SQLException;import org.ThreeLayer.Entity.Student;public class DButil { public static final String driver = "com.mysql.cj.jdbc.Driver"; public static final String url = "jdbc:mysql://localhost:3306/zxy?&useSSL=false&serverTimezone=UTF-8&useSSL=false&serverTimezone = GMT"; public static final String username = "root"; public static final String password = "zxy170518."; public static Connection connection = null;//鏈接數(shù)據(jù)庫(kù) public static PreparedStatement pstmt=null;//執(zhí)行sql語(yǔ)句  public static ResultSet rs=null;   public static Connection getConnection() throws SQLException, ClassNotFoundException { Class.forName(driver); return DriverManager.getConnection(url,username,password); }  public static int getTotalCount(String sql) { int count=0; try { pstmt=createPrepareStatement(sql, null); rs=pstmt.executeQuery(); if(rs.next()) { count=rs.getInt(1); } }catch(SQLException e) { e.printStackTrace(); }catch(ClassNotFoundException e) { e.printStackTrace(); }catch(Exception e) { e.printStackTrace(); }finally { closeAll(connection, pstmt, rs); } return count; }  public static PreparedStatement createPrepareStatement(String sql,Object[] obj) throws ClassNotFoundException, SQLException { pstmt=getConnection().prepareStatement(sql); if(obj!=null) { for(int i=0;i<obj.length;i++) { pstmt.setObject(i+1, obj[i]);//進(jìn)行更新動(dòng)作 } } return pstmt; }  public static boolean UpdateSQL(String sql,Object[] obj) { try  { pstmt=createPrepareStatement(sql, obj); int count=pstmt.executeUpdate(); if(count>0) { return true; } else { return false; } } catch (ClassNotFoundException e) { // TODO Auto-generated catch block e.printStackTrace(); return false; } catch (SQLException e) { // TODO Auto-generated catch block e.printStackTrace(); return false; }finally { closeAll(connection,pstmt,rs); } }   public static ResultSet FindSQL(String sql,Object[] obj) { try { pstmt=createPrepareStatement(sql, obj); rs=pstmt.executeQuery(); return rs; }catch(ClassNotFoundException e) { e.printStackTrace(); return rs; } catch (SQLException e) { // TODO Auto-generated catch block e.printStackTrace(); return rs; }catch(Exception e) { e.printStackTrace(); return rs; } }  public static void closeAll(Connection connection,PreparedStatement pstmt,ResultSet rs) { try { if(connection!=null); connection.close(); if(pstmt!=null); pstmt.close(); if(rs!=null); rs.close(); } catch (SQLException e) { // TODO Auto-generated catch block e.printStackTrace(); }catch(Exception e) { e.printStackTrace(); } }}

基本上就是普通的數(shù)據(jù)庫(kù)操作功能，很好懂，就不多解釋了；
對(duì)于數(shù)據(jù)訪問(wèn)層的Dao：

public int getTotalCount()//查詢數(shù)據(jù)總數(shù) { String sql="select count(1) from student"; return DButil.getTotalCount(sql); }  public List<Student> findStudentByPage(int currentPage,int pageSize)//currentPage：當(dāng)前頁(yè)數(shù)；pageSize頁(yè)面所能容納的最大數(shù)據(jù)量 { String sql="select * from student limit ? , ?"; Object[] obj= {currentPage*pageSize,pageSize}; List<Student> students=new ArrayList<>(); ResultSet rs=DButil.FindSQL(sql, obj); try { while(rs.next()) { Student student=new Student(rs.getInt(1),rs.getString(2),rs.getString(3),rs.getInt(4)); students.add(student); } } catch (SQLException e) { // TODO Auto-generated catch block e.printStackTrace(); }catch (Exception e) { // TODO Auto-generated catch block e.printStackTrace(); } return students; }

對(duì)于業(yè)務(wù)邏輯層：

Server：

public int getTotalCount() { return studentdao.getTotalCount(); }  public List<Student> findStudentByPage(int currentPage,int pageSize) { return studentdao.findStudentByPage(currentPage, pageSize); }

對(duì)于視圖層的后臺(tái)代碼：

Servlet：

package org.Three.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 org.ThreeLayer.Entity.Page_S;import org.ThreeLayer.Entity.Student;import org.ThreeLayer.Server.Student_Server;public class findStudentByPage extends HttpServlet { protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException { Student_Server studentS=new Student_Server(); // int currentPage=2;  Page_S pag=new Page_S();  String tmp=request.getParameter("currentPage"); if(tmp==null)//判斷是否為第一次進(jìn)行訪問(wèn) { tmp="0"; }  int sum=studentS.getTotalCount(); pag.setTotalCount(sum);  int currentPage= Integer.parseInt(tmp); pag.setCurrentPage(currentPage);  String tmp2=request.getParameter("choose"); if(tmp2==null)//默認(rèn)一頁(yè)3個(gè)內(nèi)容 { tmp2="3"; }  int pageSize=Integer.parseInt(tmp2); pag.setPageSize(pageSize); List<Student> students =studentS.findStudentByPage(currentPage, pageSize); pag.setStudents(students); request.setAttribute("pag", pag); request.getRequestDispatcher("index.jsp").forward(request, response); System.out.print(students); System.out.print(sum); } protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException { doGet(request, response); }}

還有一個(gè)實(shí)體類：Page：

package org.ThreeLayer.Entity;import java.util.List;public class Page_S {//為了不出現(xiàn)于重名，改了一下 private int currentPage; private int pageSize;//頁(yè)面大小，即頁(yè)面數(shù)據(jù)個(gè)數(shù) private int totalCount;//總數(shù)據(jù) private int totalPage;//總頁(yè)數(shù) private List<Student> students; public Page_S() { } public Page_S(int currentPage, int pageSize, int totalCount, int totalPage, List<Student> students) { this.currentPage = currentPage; this.pageSize = pageSize; this.totalCount = totalCount; this.totalPage = totalPage; this.students = students; } public int getCurrentPage() { return currentPage; } public void setCurrentPage(int currentPage) { this.currentPage = currentPage; } public int getPageSize() { return pageSize; } public void setPageSize(int pageSize) { this.pageSize = pageSize; this.totalPage=this.totalCount%this.pageSize==0?this.totalCount/this.pageSize:this.totalCount/this.pageSize+1; } public int getTotalCount() { return totalCount; } public void setTotalCount(int totalCount) { this.totalCount = totalCount; } public int getTotalPage() { return totalPage; } public void setTotalPage(int totalPage) { this.totalPage = totalPage; } public List<Student> getStudents() { return students; } public void setStudents(List<Student> students) { this.students = students; }}

最后貼上index.jsp：

<%@page import="java.util.List"%><%@page import="org.ThreeLayer.Entity.Student"%><%@page import="org.ThreeLayer.Entity.Page_S"%><%@ page language="java" contentType="text/html; charset=UTF-8" pageEncoding="UTF-8"%><!DOCTYPE html><html><head><meta charset="UTF-8"><title>學(xué)生信息管理</title></head><body> <table border=1px> <tr> <th>學(xué)號(hào)</th> <th>姓名</th> <th>性別</th> <th>操作</th> </tr> <% Page_S pagg=(Page_S)request.getAttribute("pag"); for(Student student:pagg.getStudents()) { %> <tr> <th><a href="FindStudentById_Servlet?uid=<%=student.getId()%>" ><%=student.getId() %></a></th> <th><%=student.getName() %></th> <th><%=student.getSex() %></th> <th><a href="DeleteStudent_Servlet?uid=<%=student.getId()%>" >刪除</a></th> </tr> <% } %> </table> <a href="add.jsp" >增加</a> <% if(pagg.getCurrentPage()==0)//用戶位于首頁(yè)的時(shí)候 { %>  <a href="findStudentByPage?currentPage=<%=pagg.getCurrentPage()+1%>" >下一頁(yè)</a> <a href="findStudentByPage?currentPage=<%=pagg.getTotalPage()-1%>" >尾頁(yè)</a> <%  }else if(pagg.getCurrentPage()==pagg.getTotalPage()-1)//用戶位于尾頁(yè)的時(shí)候 { %> <a href="findStudentByPage?currentPage=0" >首頁(yè)</a> <a href="findStudentByPage?currentPage=<%=pagg.getCurrentPage()-1%>" >上一頁(yè)</a> <%  }else//用戶位于中間頁(yè)面的時(shí)候 { %> <a href="findStudentByPage?currentPage=0" >首頁(yè)</a> <a href="findStudentByPage?currentPage=<%=pagg.getCurrentPage()+1%>" >下一頁(yè)</a> <a href="findStudentByPage?currentPage=<%=pagg.getCurrentPage()-1%>" >上一頁(yè)</a> <a href="findStudentByPage?currentPage=<%=pagg.getTotalPage()-1%>" >尾頁(yè)</a> <% } %>  <br></body></html>

看一下效果圖：

首先看數(shù)據(jù)庫(kù)內(nèi)容：

然后是首頁(yè)：

下一頁(yè)：

最后是尾頁(yè)：

總的說(shuō)明一下：

首先對(duì)于功能的闡述，第一步計(jì)算總的數(shù)據(jù)量，然后規(guī)定默認(rèn)容量大小為3，最終在jsp代碼中加上跟用戶進(jìn)行交互的功能，即讓用戶選擇一頁(yè)多少內(nèi)容（由于我寫的那個(gè)有點(diǎn)bug，就先不貼，等后面自己能完美實(shí)現(xiàn)之后，再更新），之后對(duì)前端數(shù)據(jù)進(jìn)行打包，要思考的是，我們對(duì)于這個(gè)功能我們所需要的數(shù)據(jù)有哪些呢？首先，總數(shù)據(jù)量要吧？然后要存放總的數(shù)據(jù)內(nèi)容吧？然后頁(yè)面大小需要吧？然后用戶所在頁(yè)面的那個(gè)頁(yè)面位置的數(shù)要吧？最后一個(gè)就是通過(guò)總數(shù)據(jù)量和頁(yè)面大小計(jì)算出來(lái)的總頁(yè)面數(shù)也需要吧？所以，一共就需要記錄5個(gè)屬性值，那就打包成一個(gè)JavaBean吧，前面代碼也貼出來(lái)了。最后要提一點(diǎn)，對(duì)于如果我第一次進(jìn)行訪問(wèn)頁(yè)面的時(shí)候，我應(yīng)該是有一些屬性值是為null的，這樣是會(huì)報(bào)空指針異常的，那么就要進(jìn)行一些小小的處理，哪些呢？比如如果用戶第一次進(jìn)行訪問(wèn)，系統(tǒng)是收不到用戶當(dāng)前所在頁(yè)面的頁(yè)面數(shù)值的，那么就要判斷一下，（此處上代碼）如果是第一次進(jìn)行訪問(wèn)，那么就給與一個(gè)默認(rèn)值0，也就是第一頁(yè)，那么就處理好了這個(gè)小問(wèn)題了，諸如此類問(wèn)題還有就是用戶在進(jìn)行選擇一頁(yè)多少內(nèi)容的時(shí)候，也是需要進(jìn)行賦予一個(gè)默認(rèn)值的，不然也會(huì)報(bào)空指針。然后對(duì)于web.xml文件內(nèi)容的設(shè)置，首頁(yè)應(yīng)該設(shè)置為實(shí)現(xiàn)分頁(yè)功能的Servlet，因?yàn)槟忝孔鲆淮畏?yè)或者首次訪問(wèn)，雖然都是在index.jsp中，但是你需要把每次做完動(dòng)作之后得到的新的內(nèi)容進(jìn)行請(qǐng)求轉(zhuǎn)發(fā)，這樣才能實(shí)現(xiàn)更新，不然程序會(huì)報(bào)錯(cuò)。

以上就是本文的全部?jī)?nèi)容，希望對(duì)大家的學(xué)習(xí)有所幫助，也希望大家多多支持。