javaweb基础——简单的分页逻辑

前言:分页有两种，真分页和假分页，两者区别点击这里，我也有好多代码都是看他的。话不多说，直接上代码。

一.首先创建一个页面信息实体类。

package com;

import java.util.List;

public class PageBean {


        private int page;//当前页
        
        private int pagesize;//页面数据条数
        
        private int indexpage=1;//首页
        
        private int endpage;//尾页
        
        private int count;//总数据条数
        
        private int pagenumber;//总页面数
        
        private List<Object> list;//得到的数据放入list集合中
        
        public int getPage() {
            return page;
        }
        public void setPage(int page) {
            this.page = page;
        }
        public int getPagesize() {
            return pagesize;
        }
        public void setPagesize(int pagesize) {
            this.pagesize = pagesize;
        }
        public int getIndexpage() {
            return indexpage;
        }
        public void setIndexpage(int indexpage) {
            this.indexpage = indexpage;
        }
        public int getEndpage() {
            
            return endpage;
        }
        public void setEndpage() {
            this.endpage=pagenumber;
        }
        public int getCount() {
            this.count=list.size();
            return count;
        }
        public void setCount() {
            this.count=list.size();
        }
        
        public int getPagenumber() {
            return pagenumber;
        }
        public void setPagenumber() {
            this.pagenumber=(count%pagesize==0)?count/pagesize:count/pagesize+1;
        }
        public List<Object> getList() {
            return list;
        }
        public void setList(List<Object> list) {
            this.list = list;
        }
        @Override
        public String toString() {
            return "PageBean [page=" + page + ", pagesize=" + pagesize + ", indexpage=" + indexpage + ", endpage="
                    + endpage + ", count=" + count + ", pagenumber=" + pagenumber + ", list=" + list + "]";
        }

    }

2.接着创建一个接收前端页面传过来的值和返回值给前端的servlet

package com;

import java.io.IOException;
import java.util.ArrayList;
import java.util.List;

import javax.servlet.ServletException;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import javax.servlet.http.HttpSession;

@SuppressWarnings("serial")
public class FirstServlet extends HttpServlet{
    @Override
    protected void doGet(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
        
        
        
        // TODO Auto-generated method stub
        System.out.println("-----------------------------进入-------------------------");
        
        
        //定义一个对象集合，存储数据,并且创建了53条数据
        List<Object> list1=new ArrayList<Object>();
        for(int i=0;i<53;i++){
            User user=new User();
            user.setAge(11);
            user.setName("bobo"+i);
            list1.add(user);
        }

        
        //1.接受前端的要跳转到的目标页的页面值
        String str_page=    req.getParameter("page");
        
        
        
        
        //2.创建pageBean实例
        PageBean pagebean=new PageBean();
        pagebean.setList(list1);    //将53条数据的集合放到页面中
        pagebean.setCount();        //数据条数
        pagebean.setPagesize(5);    //每页大小
        pagebean.setPagenumber();//总页面数
        pagebean.setEndpage();    //伟业
        pagebean.setIndexpage(1);    //首页

            
        //3.定义一个集合，该集合存放目标页要显示的5条数据，最后一页不一定是5条
        List<Object> currentData=new ArrayList<Object>();
        //4.1.判断前端要跳转到的目标页的页面值，我这里初始化页面是从servlet进入，所以首次是一个空值。2.如果已经是首页，但用户的错误操作点击上一页
        //那目标也应该还是首页，
        if(str_page==null||Integer.parseInt(str_page)<1)
        {
            pagebean.setPage(1);
        
        }
        //如果为尾页，还点击下一页，那目标也还是在尾页
        else if(Integer.parseInt(str_page)>pagebean.getPagenumber()){
            pagebean.setPage(pagebean.getPagenumber());
        }
        //其他正常情况
        else{
            pagebean.setPage(Integer.parseInt(str_page));
        }
        
        //确定目标页显示的数据列表
        for(int index=(pagebean.getPage()-1)*pagebean.getPagesize();index<pagebean.getPage()*pagebean.getPagesize()&&index<pagebean.getCount();index++){
            User user=new User();
            currentData.add(list1.get(index));
        }
        
//        System.out.println(pagebean.toString());
        HttpSession session=req.getSession();
        //    session.setAttribute("data", data);
            
//            System.out.println(currentData.toString());
            //session.setAttribute("currentPage", currentPage);
        //传递当前页应取得的数据，和页面信息
          session.setAttribute("pageInfo", pagebean);
         session.setAttribute("userList", currentData);
        req.getRequestDispatcher("first.jsp").forward(req, resp);
    }
    
    @Override
    protected void doPost(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
        // TODO Auto-generated method stub
    doGet(req,resp);

}
    }

3.最后，写jsp代码

<%@ page language="java" contentType="text/html; charset=utf-8"
    pageEncoding="utf-8"
   import="java.util.*" 
   import="com.User"
   import="com.PageBean"%>
    
    <%@ taglib prefix="c" uri="http://java.sun.com/jsp/jstl/core" %>
 <%  List<User> userList=(List<User>)session.getAttribute("userList");
         request.setAttribute("userList",userList);
         PageBean pageBean=(PageBean)session.getAttribute("pageInfo");
          request.setAttribute("pageBean",pageBean);
     %>  
<!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=utf-8">
<title>Insert title here</title>
<script type=“text/javascript" src="jquery-1.4.3.min.js"></script>
<script type="text/javascript" src="first.js"></script>
</head>
<body>
<div id="content_right">
                        <br />
                        <br />

                        <div class="btwz">
                            人员列表
                        </div>
                        <br>
                        <form name="form1" action="Staff_InfoServlet" method="post">
                            <table cellspacing="1" class="table">
                                <tr class="table_header">
                                    <td valign="middle" align="left">
                                        姓名
                                    </td>
                                    <td valign="middle" align="left">
                                        年龄
                                    </td>
                                 
                                </tr>
                                <c:forEach items="${userList}" var="list">
                                <tr class="row2" onMouseOver="this.className='row1'"
                                    onMouseOut="this.className='row2'">
                                    <td valign="middle" align="left">
                                        ${list.name}
                                    </td>
                                    <td valign="middle" align="left">
                                        ${list.age}
                                    </td>
                              </tr>
                             </c:forEach>
                             
                            </table>
                        </form>
                       
                   

                        <p class="paging">
                            <a href="/Test/First.action?page=${pageBean.indexpage}">首页</a>
                            <a href="/Test/First.action?page=${pageBean.page-1}">    &lt; 上一页 </a>
                            <strong>第${pageBean.page}页/共${pageBean.pagenumber}页</strong>
                            <a href="/Test/First.action?page=${pageBean.page+1}">下一页 &gt;</a>
                          
                        </p>
                        <br />
                        <br />
                    </div>
                </div>
            </div>
</body>
</html>

　　注释已经很详细了，基本上很明了。我也不做过多的赘述了。以后有发现再来。