jsp servlet javaBean后台分页实例代码解析

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

导入的包

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="http://java.sun.com/jsp/jstl/core"%>
<!doctype html public "-//w3c//dtd html 4.01 transitional//en" "http://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="http://www.w3.org/2001/xmlschema-instance" xmlns="http://java.sun.com/xml/ns/javaee" xsi:schemalocation="http://java.sun.com/xml/ns/javaee http://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

数据库describe

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。

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