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JSP實(shí)現(xiàn)分頁(yè)效果

更新時(shí)間：2019年11月08日 13:41:17 作者：Link_zx

這篇文章主要為大家詳細(xì)介紹了JSP實(shí)現(xiàn)分頁(yè)效果，文中示例代碼介紹的非常詳細(xì)，具有一定的參考價(jià)值，感興趣的小伙伴們可以參考一下

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(xún)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(lèi)：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(hù)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(hù)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(hù)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(hù)進(jìn)行交互的功能，即讓用戶(hù)選擇一頁(yè)多少內(nèi)容（由于我寫(xiě)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(hù)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(hù)第一次進(jìn)行訪問(wèn)，系統(tǒng)是收不到用戶(hù)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(lèi)問(wèn)題還有就是用戶(hù)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腳本之家。

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