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[JSP] jsp servlet javaBean后台分页实例代码解析

开发技术 开发技术 发布于：2021-10-20 22:20 | 阅读数：461 | 评论：0

首先后台分页需要理清分页思路，把数据库里面需要分页的信息放到List集合中，然后按照页面反馈给后台的页码对List集合进行SubList切割把切完的List传到前端进行显示。

1.分页的demo文件结构图
DSC0000.jpg

导入的包
DSC0001.jpg

2.代码

SplitPageServlet代码
package ActionServlet;
import java.io.IOException;
import java.sql.SQLException;
import java.util.ArrayList;
import java.util.List;
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 Bean.ProjectBean;
import Service.SplitPage;
/**
 * Servlet implementation class SplitPageServlet
 */
@WebServlet("/SplitPageServlet")
public class SplitPageServlet extends HttpServlet {
 private static final long serialVersionUID = 1L;
  
 /**
  * @see HttpServlet#HttpServlet()
  */
 public SplitPageServlet() {
  super();
  // TODO Auto-generated constructor stub
 }
 /**
  * @see HttpServlet#doGet(HttpServletRequest request, HttpServletResponse response)
  */
 protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
  // TODO Auto-generated method stub
  List<ProjectBean>listArr = new ArrayList<ProjectBean>();
  String currrentPageString = request.getParameter("currrentPage");
  String numberForSplitPage = request.getParameter("numberForSplitPage");
  if( currrentPageString ==null){
   currrentPageString = "1";
  }
  if( numberForSplitPage == null){
   numberForSplitPage = "5";
  }
  SplitPage splitPage = new SplitPage();
  try {
   listArr = splitPage.AllSplitPage(numberForSplitPage, currrentPageString);
   request.setAttribute("subResult", listArr);
  } catch (ClassNotFoundException | SQLException e) {
   // TODO Auto-generated catch block
   e.printStackTrace();
  }
  System.out.println(SplitPage.pageNumber);
  System.out.println(SplitPage.currentPageIndex);
  request.setAttribute("pageNumber", SplitPage.pageNumber);
  request.setAttribute("currentPageIndex", SplitPage.currentPageIndex);
  request.getRequestDispatcher("/servlet/ShowViewIndex").forward(request, response);
  
 }
 /**
  * @see HttpServlet#doPost(HttpServletRequest request, HttpServletResponse response)
  */
 protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
  // TODO Auto-generated method stub
  doGet(request, response);
 }
}
ProjectBean代码
package Bean;
public class ProjectBean {
 private String projectId = null;
 private String projectName = null;
 private String projectType = null;
 private String userNo = null;
 private String projectUser = null;
 public String getProjectId(){
  if(projectId==null){
   projectId ="";
  }
  return this.projectId;
 }
 public void setProjectId(String projectId){
  this.projectId = projectId;
 }
 
 public void setProjectName(String projectName){
  this.projectName = projectName;
 }
 
 public String getProjectName(){
  return this.projectName;
 }
 
 public void setType(String projectType){
  this.projectType = projectType;
 }
 
 public String getProjectType(){
  return this.projectType;
 }
 
 public void setUserNo(String userNo){
  this.userNo = userNo;
 }
 
 public String getUserNo(){
  return this.userNo;
 }
 
 public void setProjectUser(String projectUser){
  this.projectUser = projectUser;
 }
 
 public String getProjectUser(){
  return this.projectUser;
 }
 
}
SplitPageBean 代码
package Bean;
public class SplitPageBean {
 private int allitems;//总的记录数
 private int currentRecord;//当前的记录数
 private int lastPageRecord ; //上一页记录数开始数
 private int nextPageRecord;//下一页记录数开始数
 private int lastPageIndex ; //上一页
 private int nextPageIndex;//下一页
 private int currentPageIndex;//当前页
 private int numberForSplitPage;//每页分的数量
 private int allPageNumber;
 public int getAllitems(){
  return this.allitems;
 }
 public void setAllitems(int allitems){
  this.allitems = allitems; 
 }
 
 public int getCurrentRecord(){
  return this.currentRecord;
 }
 public void setCurrentRecord(int currentPageIndex){
  this.currentRecord = currentPageIndex * this.numberForSplitPage; 
 }
 
 public int getlastPageRecord(){
  return this.lastPageRecord;
 }
 public void setLastPageRecord(int lastPageIndex){
  this.lastPageRecord = lastPageIndex * this.numberForSplitPage; 
 }
 
 public int getNextPageRecord(){
  return this.nextPageRecord;
 }
 public void setNextPageRecord(int nextPageIndex){
  this.nextPageRecord = nextPageIndex * this.numberForSplitPage; 
 }
 
 public int getLastPageIndex(){
  return this.lastPageIndex;
 }
 public void setLastPageIndex(int currentPageIndex){
  this.lastPageIndex = currentPageIndex - 1; 
 }
 
 public int getNextPageIndex(){
  return this.nextPageIndex;
 }
 public void setNextPageIndex(int currentPageIndex){
  this.nextPageIndex = currentPageIndex - 1; 
 }
 
 public int getCurrentPageIndex(){
  return this.currentPageIndex;
 }
 public void setCurrentPageIndex(int currentPageIndex){
  this.currentPageIndex = currentPageIndex; 
 }
 
 public int getNumberForSplitPage(){
  return this.numberForSplitPage;
 }
 public void setNumberForSplitPage(int numberForSplitPage){
  this.numberForSplitPage = numberForSplitPage; 
 }
 
 public int getAllPageNumber(){
  return this.allPageNumber;
 }
 public void setAllPageNumber(int allitems){
  this.allPageNumber = allitems / this.numberForSplitPage + 1; 
 } 
 
}
QueryProject代码
package Dao;
import java.sql.Connection;
import java.sql.ResultSet;
import java.sql.SQLException;
import java.sql.Statement;
import java.util.ArrayList;
import java.util.List;
import Bean.ProjectBean;
import Service.ConnectDataBase;
public class QueryProject {
 private List<ProjectBean> listArr = new ArrayList();
 public List<ProjectBean> QueryAllProject() throws ClassNotFoundException, SQLException{
  Connection conn=null;
  Statement stat=null;
  ResultSet rs=null;
  ConnectDataBase connectDataBase =new ConnectDataBase();
  conn = connectDataBase.connect();
  stat = conn.createStatement();
  rs = stat.executeQuery("select*from project");
  
  while(rs.next()){
   ProjectBean projectBean = new ProjectBean();
   projectBean.setProjectId(rs.getString("projectId"));
   projectBean.setProjectName(rs.getString("projectName"));
   projectBean.setType(rs.getString("projectType"));
   projectBean.setUserNo(rs.getString("UserNo"));
   projectBean.setProjectUser(rs.getString("projectUser"));
   listArr.add(projectBean);
  }
  connectDataBase.close(stat, conn);
  return listArr;
 }
// public static void main(String[] args) throws ClassNotFoundException, SQLException{
//  List<ProjectBean> listArr = new ArrayList();
//  QueryProject queryProject = new QueryProject();
//  listArr = queryProject.QueryAllProject();
//  ProjectBean projectBean = new ProjectBean();
//  projectBean = listArr.get(0);
//  System.out.println(projectBean.getProjectId());
//  projectBean = listArr.get(2);
//  System.out.println(projectBean.getProjectId());
//  System.out.println(listArr.size());
// }
}
ConenctDataBase代码
package Service;
import java.sql.Connection;
import java.sql.DriverManager;
import java.sql.SQLException;
import java.sql.Statement;
public class ConnectDataBase {
 private String url = "jdbc:MySQL://localhost:3306/zhongchuangweb";
 private String user = "root";
 private String password = "12345";
 
 public Connection connect() throws ClassNotFoundException, SQLException{
   Class.forName("com.mysql.jdbc.Driver");
   Connection conn = DriverManager.getConnection(url,user,password); 
   return conn;
 }
 //关闭数据库资源
 public void close(Statement stat,Connection conn) throws SQLException{
  if(stat!=null){
  stat.close();
  }
  if(conn!=null){
  conn.close();
  }
 }
}
SplitPage代码
package Service;
import java.sql.SQLException;
import java.util.ArrayList;
import java.util.List;
import Bean.ProjectBean;
import Bean.SplitPageBean;
import Dao.QueryProject;
public class SplitPage {
 public static int pageNumber;
 public static int currentPageIndex;
 private List<ProjectBean> splitArr = new ArrayList(); 
 {
  QueryProject queryProject = new QueryProject();
  try {
   splitArr = queryProject.QueryAllProject();
  } catch (ClassNotFoundException | SQLException e) {
   // TODO Auto-generated catch block
   e.printStackTrace();
  }
 }
 public List<ProjectBean> AllSplitPage(String numberForSplitPage,String requestPageIndex) throws ClassNotFoundException, SQLException{
  List<ProjectBean> result = new ArrayList<ProjectBean>(); 
  int numberForSplitPageInt = Integer.parseInt(numberForSplitPage);//每页的数量
  int requestPageIndexInt = Integer.parseInt(requestPageIndex);//请求的页码
  SplitPageBean splitPageBean = new SplitPageBean();
  splitPageBean.setAllitems(splitArr.size());//设置总的记录数
  splitPageBean.setNumberForSplitPage(numberForSplitPageInt);//设置每页的记录数量
  splitPageBean.setAllPageNumber(splitArr.size());
  pageNumber = splitPageBean.getAllPageNumber();
  splitPageBean.setCurrentPageIndex(requestPageIndexInt);//设置请求页页码
  currentPageIndex = splitPageBean.getCurrentPageIndex();
  splitPageBean.setLastPageRecord(requestPageIndexInt-1);
  if(splitPageBean.getAllitems()<splitPageBean.getNumberForSplitPage()){
   result = splitArr;
  }else if(splitPageBean.getCurrentPageIndex()*splitPageBean.getNumberForSplitPage() > splitPageBean.getAllitems()){
   result = splitArr.subList(splitPageBean.getlastPageRecord(),splitPageBean.getAllitems());
  }else{
   result = splitArr.subList(splitPageBean.getlastPageRecord(),splitPageBean.getlastPageRecord()+splitPageBean.getNumberForSplitPage());//SubList用法不包含末尾索引
  }
  return result;
 }
 
// public static void main(String[] args) throws ClassNotFoundException, SQLException{
//  List<ProjectBean> TestResult = new ArrayList<ProjectBean>(); 
//  ProjectBean projectBean = new ProjectBean();
//  SplitPage splitPage = new SplitPage();
//  TestResult = splitPage.AllSplitPage("5","1");
//  projectBean = TestResult.get(0);
//  System.out.println(projectBean.getProjectId());
//  projectBean = TestResult.get(1);
//  System.out.println(projectBean.getProjectId());
//  projectBean = TestResult.get(2);
//  System.out.println(projectBean.getProjectId());
//  projectBean = TestResult.get(3);
//  System.out.println(projectBean.getProjectId());
//  projectBean = TestResult.get(4);
//  System.out.println(projectBean.getProjectId());
//  projectBean = TestResult.get(5);
//  System.out.println(projectBean.getProjectId());
//  
// }
}
显示层
ShowViewIndex代码
package View;
import java.io.IOException;
import javax.servlet.ServletException;
import javax.servlet.annotation.WebServlet;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
/**
 * Servlet implementation class ShowViewIndex
 */
@WebServlet("/ShowViewIndex")
public class ShowViewIndex extends HttpServlet {
 private static final long serialVersionUID = 1L;
  
 /**
  * @see HttpServlet#HttpServlet()
  */
 public ShowViewIndex() {
  super();
  // TODO Auto-generated constructor stub
 }
 /**
  * @see HttpServlet#doGet(HttpServletRequest request, HttpServletResponse response)
  */
 protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
  // TODO Auto-generated method stub
  request.getRequestDispatcher("/NewFile.jsp").forward(request, response);
 }
 /**
  * @see HttpServlet#doPost(HttpServletRequest request, HttpServletResponse response)
  */
 protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
  // TODO Auto-generated method stub
  doGet(request, response);
 }
}
jsp页面代码
<%@ page language="java" contentType="text/html; charset=utf-8"
 pageEncoding="utf-8"%>
<%@ taglib prefix="c" uri="https://java.sun.com/jsp/jstl/core"%>
<!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" "https://www.w3.org/TR/html4/loose.dtd">
<html>
<head>
<meta http-equiv="Content-Type" content="text/html; charset=ISO-8859-1">
<title>数据库内容分页显示</title>
<style type="text/css">
*{ margin:0; padding:0;}
ul li{ width:50px; height:24px; line-height:24px; float:left; margin-left:0px; display:inline; margin-top:5px; overflow:hidden;}
ul li button{width:50px;height:24px;margin:0px;padding:0px;}
</style>
</head>
<body>
 <table>
  <thead>
   <tr>
  <th style="text-align:center;">编号</th>
  <th style="text-align:center;">名称</th>
  <th style="text-align:center;">类型</th>
  <th style="text-align:center;">学号</th>
  <th style="text-align:center;">负责人</th>
   </tr>
  </thead>
  <tbody>
  <c:forEach var="project" items="${subResult}">
   <tr>
    <td><c:out value="${project.projectId}"></c:out></td>
    <td><c:out value="${project.projectName}"></c:out></td>
    <td><c:out value="${project.projectType}"></c:out></td>
    <td><c:out value="${project.userNo}"></c:out></td>
    <td><c:out value="${project.projectUser}"></c:out></td>
   </tr>
  </c:forEach>
  </tbody>
 </table>
 <div align = "center">
  <ul>
  <c:choose>
   <c:when test="${currentPageIndex>1}">
     <li><a href="${pageContext.request.contextPath}/servlet/SplitPageServlet?currrentPage=${currentPageIndex-1}"><button><</button></a></li>
   </c:when>
   <c:otherwise>
     <li><a><button><</button></a></li>
   </c:otherwise>
  </c:choose>
   <%
    int i =(Integer)request.getAttribute("pageNumber");
     for (int j=0;j<i;j++)
     {%>
     <li><a href="${pageContext.request.contextPath}/servlet/SplitPageServlet?currrentPage=<%=j+1%>"><button><%=j+1%></button></a></li>
    <%}%>
   <c:choose>
   <c:when test="${currentPageIndex+1<=pageNumber}">
     <li><a href="${pageContext.request.contextPath}/servlet/SplitPageServlet?currrentPage=${currentPageIndex+1}"><button>></button></a></li>
   </c:when>
   <c:otherwise>
     <li><a><button>></button></a></li>
   </c:otherwise>
  </c:choose>
  </ul> 
   </div> 
</body>
</html>
xml代码
<?xml version="1.0" encoding="UTF-8"?>
<web-app xmlns:xsi="https://www.w3.org/2001/XMLSchema-instance" xmlns="https://java.sun.com/xml/ns/javaee" xsi:schemaLocation="https://java.sun.com/xml/ns/javaee https://java.sun.com/xml/ns/javaee/web-app_2_5.xsd" version="2.5">
 <display-name></display-name>
 <welcome-file-list>
 <welcome-file>SplitPageServlet</welcome-file>
 </welcome-file-list> 
 <servlet>
 <servlet-name>ShowViewIndex</servlet-name>
 <servlet-class>View.ShowViewIndex</servlet-class>
 </servlet>
 <servlet-mapping>
 <servlet-name>ShowViewIndex</servlet-name>
 <url-pattern>/servlet/ShowViewIndex</url-pattern>
 </servlet-mapping>
 <servlet>
 <servlet-name>SplitPageServlet</servlet-name>
 <servlet-class>ActionServlet.SplitPageServlet</servlet-class>
 </servlet>
 <servlet-mapping>
 <servlet-name>SplitPageServlet</servlet-name>
 <url-pattern>/servlet/SplitPageServlet</url-pattern>
 </servlet-mapping>
</web-app>
运行结果展示
DSC0002.jpg

数据库describe
DSC0003.jpg

同时在本次demo中认识到了xml的中使用欢迎界面通过  <welcome-file-list>  <welcome-file>静态界面（jsp html）</welcome-file> </welcome-file-list>还可以使用servlet直接用servlet名即可。
初学java和javaee 写一点自己做的东西，代码写的不是很规范，不喜勿喷。
以上就是本文的全部内容，希望对大家的学习有所帮助，也希望大家多多支持CodeAE代码之家。

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