新闻发布系统 分页实现

实现效果图：

当点击下一页时地址变成?pageIndex =2：

因为是分页，所以可以根据分页的需求定制出页面类代码如图：

package cn.news.util;

import java.util.List;

import cn.news.entity.NewsDetail;

public class Page {
    //泛型
    private List<NewsDetail> list;

    public List<NewsDetail> getList() {
        return list;
    }
    public void setList(List<NewsDetail> list) {
        this.list = list;
    }
    public int getPageIndex() {
        return pageIndex;
    }
    public void setPageIndex(int pageIndex) {
        this.pageIndex = pageIndex;
    }
    public int getPageSize() {
        return pageSize;
    }
    public void setPageSize(int pageSize) {
        this.pageSize = pageSize;
    }
    public int getTotalPages() {
        return totalPages;
    }
    public void setTotalPages(int totalPages) {
        this.totalPages = totalPages;
    }
    public int getTotalRecords() {
        return totalRecords;
    }
    public void setTotalRecords(int totalRecords) {
        this.totalRecords = totalRecords;
    }
    //当前页
    private int pageIndex;
    //页的大小
    private int pageSize;
    //总页数
    private int totalPages;
    //总记录数
    private int totalRecords;

}

在newsdetaildao 数据访问层编写代码：

package cn.news.dao;

import java.util.List;

import cn.news.entity.NewsDetail;

/**
 * 接口
 * @author happy
 *
 */
public interface NewsDetailDAO {
    //1.1 写一个查询所有新闻纪录的方法
  public List<NewsDetail> getAllNews() throws Exception;
  public List<NewsDetail> getOnePageNews(int pageIndex,int pageSize) throws Exception;
  public int getCount() throws Exception;
  public int login(NewsDetail news) throws Exception;
}

编写其实现类：

package cn.news.dao.imp;

import java.sql.ResultSet;
import java.util.ArrayList;
import java.util.List;

import org.junit.Test;

import cn.news.dao.BaseDao;
import cn.news.dao.NewsDetailDAO;
import cn.news.entity.NewsDetail;

public class NewsDetailImpl extends BaseDao implements NewsDetailDAO {

    public List<NewsDetail> getAllNews() throws Exception {
        List<NewsDetail> list =new ArrayList<NewsDetail>();
        String sql ="select * from newsDetails";
        ResultSet rs = executeQuery(sql);

        if (rs!=null) {
            while(rs.next()){
                NewsDetail news=new NewsDetail();
                news.setNewsId(rs.getInt("newsId"));
                news.setNewsTitle(rs.getString("newsTitle"));
                news.setNewsContent(rs.getString("newsContent"));
                news.setNewsCreateDate(rs.getDate("newsCreateDate"));
                news.setNewsAuthor(rs.getString("newsAuthor"));
                news.setNewsCategoryId(rs.getInt("newsCategoryId"));
                list.add(news);
            }
        }
            return list;
    }
    public List<NewsDetail> getOnePageNews(int pageIndex,int pageSize) throws Exception {
        List<NewsDetail> list=new ArrayList<NewsDetail>();
        String sql ="select top "+pageSize+" * from newsDetails where newsid not in (select top "+(pageIndex-1)*pageSize+" newsid from newsDetails)";
        ResultSet rs= executeQuery(sql);
        if(rs!=null){
            while(rs.next()){
                NewsDetail news=new NewsDetail();
                news.setNewsId(rs.getInt("newsId"));
                news.setNewsTitle(rs.getString("newsTitle"));
                news.setNewsContent(rs.getString("newsContent"));
                news.setNewsCreateDate(rs.getDate("newsCreateDate"));

                news.setNewsAuthor(rs.getString("newsAuthor"));
                news.setNewsCategoryId(rs.getInt("newsCategoryId"));
                //单个新闻对象加入新闻泛型
                list.add(news);
            }
        }
        return list;
    }
    public int getCount() throws Exception {
        String sql ="select count(1) from newsDetails";
        ResultSet rs=executeQuery(sql);
        int totalRecords=0;
        if(rs!=null){
            if(rs.next()){
                totalRecords=rs.getInt(1);
            }
        }
        return totalRecords;
    }
    public int login(NewsDetail news) throws Exception {
        // TODO Auto-generated method stub
        int flag =0;
        String sql ="select count(1) from newsDetails where newsid =? and newsCategoryId=?";
        Object [] paras ={news.getNewsId(),news.getNewsCategoryId()};
            ResultSet rs =executeQuery(sql, paras);
            if(rs!=null){
                if(rs.next()){
                    flag=1;
                }
            }
        return flag;
    }

}

在servlet类中把要显示的数据给jsp页面

package cn.news.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.junit.Test;

import cn.news.dao.imp.NewsDetailImpl;
import cn.news.entity.NewsDetail;
import cn.news.util.Page;

public class newsServlet extends HttpServlet {

    /**
     * 鎴戠殑鎴戠殑
     */
    public void doGet(HttpServletRequest request, HttpServletResponse response)
            throws ServletException, IOException {
        doPost(request, response);
    }
    /**
     *浣犵殑浣犵殑
     */
    public void doPost(HttpServletRequest request, HttpServletResponse response)
            throws ServletException, IOException {
        NewsDetailImpl dao=new NewsDetailImpl();
        try {
            Page page =new Page();
            int pageSize =3;
            page.setPageSize(pageSize);
            String temp =request.getParameter("pageIndex");
            int pageIndex ;
            if(temp!=null){
                pageIndex=Integer.parseInt(temp);
            }else{
                pageIndex=1;
            }
            page.setPageIndex(pageIndex);
            //set pagetotal
            int count =dao.getCount();
            page.setTotalRecords(count);
            int totalPages=0;
            if(count%pageSize==0){

                totalPages=count/pageSize;
            }else{
                totalPages=count/pageSize+1;
            }

            page.setTotalPages(totalPages);
            List<NewsDetail> list = dao.getOnePageNews(pageIndex, pageSize);
            page.setList(list);
            request.setAttribute("list", page);
        } catch (Exception e) {
            e.printStackTrace();
        }
        request.getRequestDispatcher("/index.jsp").forward(request, response);
    }

}

在jsp页面控制要显示的页面

 </ul>
      <ul class="classlist">
    <%
           Page page2 = (Page)request.getAttribute("list");
            //从作用域中取出一个泛型
              List<NewsDetail> list= page2.getList();
            for(NewsDetail item :list){
            //一个item就是一个新闻对象
            //item.getNewsTitle();
        %>
            <li><a href=‘newspages/news_read.jsp‘> <%=item.getNewsTitle() %> </a>
            <span> <%=item.getNewsCreateDate() %> </span></li>

       <% }

        %>
        <p align="right"> 当前页数:[<%=page2.getPageIndex() %>/<%=page2.getTotalPages() %>]&nbsp;<a href="<%=path %>/servlet/newsServlet?pageIndex=<%=page2.getPageIndex()-1 %>">上一页</a> <a href="<%=path %>/servlet/newsServlet?pageIndex=<%=page2.getPageIndex()+1 %>">下一页</a> <a href="#">末页</a> </p>
      </ul>