今天学了新闻发布系统中的使用分页技术实现页面的分页显示，感觉开始很难做，渐渐的需要动手，慢慢透析。
分页显示的步骤
1、确定每页显示的数据数量
2、计算显示的页数
3、编写
SQL语句
第一步：连接
数据库import java.sql.Connection;import java.sql.DriverManager;import java.sql.PreparedStatement;import java.sql.ResultSet;import java.sql.SQLException;import java.util.ArrayList;import java.util.List;/** * 数据库连接帮助类 * @author zql_pc * 单例设计模式 */public class DbHelp { //数据库连接对象 private Connection conn = null; //数据库连接帮助 public Connection lianjie() { if(conn==null){ //数据库配置 String driver = "oracle.jdbc.driver.OracleDriver";//驱动 String url = "jdbc:oracle:thin:@localhost:1521:NEWS";//url String username = "epet";//用户名 String password = "123456";//密码 //1.加载驱动类 try { Class.forName(driver); //2.建立连接 conn = DriverManager.getConnection(url,username,password); } catch (ClassNotFoundException e) { e.printStackTrace(); } catch (SQLException e) { e.printStackTrace(); } } return conn; } }第二步：编写新闻实体类，进行封装
/** * 新闻实体类 * @author zql_pc * */public class news { private int id; private int t_id; private String title; private String author; private String createdate; private String picpath; private String content; private String modifydate; private String summay; public int getId() { return id; } public void setId(int id) { this.id = id; } public int getT_id() { return t_id; } public void setT_id(int tId) { t_id = tId; } public String getTitle() { return title; } public void setTitle(String title) { this.title = title; } public String getAuthor() { return author; } public void setAuthor(String author) { this.author = author; } public String getCreatedate() { return createdate; } public void setCreatedate(String createdate) { this.createdate = createdate; } public String getPicpath() { return picpath; } public void setPicpath(String picpath) { this.picpath = picpath; } public String getContent() { return content; } public void setContent(String content) { this.content = content; } public String getModifydate() { return modifydate; } public void setModifydate(String modifydate) { this.modifydate = modifydate; } public String getSummay() { return summay; } public void setSummay(String summay) { this.summay = summay; }}第三步：查询新闻
import java.sql.Connection;import java.sql.PreparedStatement;import java.sql.ResultSet;import java.sql.SQLException;import java.sql.Statement;import java.util.ArrayList;import java.util.List;/** * 查询新闻 * @author zql_pc * */public class SelectNews { DbHelp help = new DbHelp(); //查询新闻数目 public int newsCount() throws SQLException{ //查询新闻条目 Connection con = help.lianjie(); //创建数据库操作对象 Statement st = con.createStatement(); String sql = "select count(*) from news"; //获得结果集 ResultSet rs = st.executeQuery(sql); //新闻数目 int newsCount = 0; while(rs.next()){ newsCount = rs.getInt(1); } return newsCount; } //计算分页 public int getPages(int newsSize) throws SQLException{ int newsCount = newsCount(); int num = (newsCount%newsSize==0)?newsCount/newsSize:newsCount/newsSize+1; return num; } //根据要求查询新闻 public List<news> getList(int pageIndex,int newsSize) throws SQLException{ //计算上限和下限 //第1页 1 - 5 // 2 6 - 10 int up = newsSize * pageIndex; int down = newsSize * (pageIndex-1)+1; //获取数据库连接对象 Connection con = help.lianjie(); String sql = "select * from " + "(select n.*,rownum r from " + "(select * from news order by ncreatedate desc) n " + "where rownum<=?) where r>=?"; PreparedStatement pst = con.prepareStatement(sql); pst.setInt(1, up); pst.setInt(2, down); //获取结果集 ResultSet rs = pst.executeQuery(); //创建集合装新闻对象 List<news> list = new ArrayList<news>(); while(rs.next()){ //创建新闻对象 news news = new news(); news.setTitle(rs.getString("ntitle")); news.setCreatedate(rs.getString("ncreatedate")); list.add(news); } return list; }}
第四步：在页面分页显示
<%@ page language="java" import="java.util.*" pageEncoding="UTF-8"%><%@page import="tools.SelectNews"%><%@page import="tools.news"%><!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN"><html> <head> </head> <body> <table align="center" border="0"> <% //展示新闻条数 int newsSize = 5; //实例化新闻帮助对象 SelectNews sn = new SelectNews(); //获取页面数量 int pages = sn.getPages(newsSize); //当前页码 int pageIndex = 1; //获取提交页码 String Pagetemp = request.getParameter("pageIndex"); //判断页面是否是当前页提交 if(Pagetemp!=null){ pageIndex = Integer.parseInt(Pagetemp); } //=============查询新闻 //获取装有新闻的集合 List<news> NewsList = sn.getList(pageIndex,newsSize); //遍历打印 for(news temp : NewsList){ %> <tr> <td><%=temp.getTitle() %></td> <td><%=temp.getCreatedate() %></td> </tr> <% } %> <tr> <td colspan="2"> <%if(!(pageIndex<=1)){ %> <a href="index.jsp?pageIndex=<%=1 %>">首页</a> <a href="index.jsp?pageIndex=<%=pageIndex-1 %>">上一页</a> <%} if(!(pageIndex>=pages)){ %> <a href="index.jsp?pageIndex=<%=pageIndex+1 %>">下一页</a> <a href="index.jsp?pageIndex=<%=pages %>">尾页</a> <%} %> <form action="index.jsp" method="post"> <input type="text" name="pageIndex" value="<%=pageIndex %>"/> <input type="submit" /> </form> </td> </tr> </table> </body></html>
原标题：输入框实现新闻列表分页显示（一）
关键词：分页
我知道了 