写一个程序让用户查询手机列表，用户输入页码，展示相应分页的手机信息（每页大小10）

package com.phone.jdbc;

import java.io.File;
import java.sql.Connection;
import java.sql.PreparedStatement;
import java.sql.ResultSet;
import java.sql.SQLException;
import java.util.Scanner;

import jxl.Workbook;
import jxl.write.Label;
import jxl.write.Number;
import jxl.write.WritableSheet;
import jxl.write.WritableWorkbook;


/**
 * 写一个程序让用户查询手机列表，用户输入页码，展示相应分页的手机信息（每页大小10）
 * @author Phone
 *
 */
public class Phone {
	
	public static void main(String[] args) throws Exception {
		Scanner sc = new Scanner(System.in);
		System.out.println("****************查询页码*****************");
		System.out.println("请输入页码：");
		int page = sc.nextInt();
		String sql ="select * from phone";
		ResultSet rs = showPage(sql, 10, page);
		while(rs.next()) {
			System.out.println(rs.getInt("pid")+"\t" + rs.getString("pmodel") + "\t"+rs.getInt("price")+"\t" +rs.getInt("pstore"));
		}
		System.out.println("***************下单******************");
		System.out.println("请输入手机id：");
		int pid = sc.nextInt();
		System.out.println("请输入数量：");
		int amount = sc.nextInt();
		placeOrder(pid,amount);
		System.out.println("****************写入xls文件中*****************");
		xls(sql);
		
	}

	/**
	 * 获取分页
	 * @param querySql 查询的sql
	 * @param pageSize 分页大小
	 * @param page 当前页码
	 */
	public static ResultSet showPage(String querySql, int pageSize, int page) {
		
		int total = getTotal(querySql);  //总记录数
		//总页数
		int totalPage = total%pageSize==0 ? total/pageSize : total/pageSize+1;
		
		System.out.println("总页数：" + totalPage);
		
		//计算起始行号和结束行号
		int start = pageSize*(page-1)+1; 
		int end = start+pageSize;
		
		//分页的sql
		String sql = "select * from " + 
				"       (select rownum rn, t.* from " + 
				"              ("+ querySql +") t " + 
				"       ) tt" + 
				"  		where tt.rn>=? and tt.rn<?";
		
		
		Connection conn = DBUtil.getConnection();
		PreparedStatement ps;
		ResultSet rs = null;
		try {
			ps = conn.prepareStatement(sql);
			ps.setInt(1, start);
			ps.setInt(2, end);
			rs = ps.executeQuery();
		
			
		} catch (SQLException e) {
			e.printStackTrace();
		}
		
		return rs;
		
	}

	//获取总记录数
	private static int getTotal(String querySql) {
		Connection conn = DBUtil.getConnection();
		PreparedStatement ps;
		int total = 0;
		try {
			ps = conn.prepareStatement("select count(*) from ("+ querySql +") t");
			ResultSet rs = ps.executeQuery();
			if(rs.next()) {
				total = rs.getInt(1);
			}
			
		} catch (SQLException e) {
			e.printStackTrace();
		}
		return total;
	}
	
	//3. 写一个程序提供下单功能，用户输入手机的id和数量，生成订单。注意库存，事务控制
	public static void placeOrder(int phoneid,int amount) {
		Connection conn = DBUtil.getConnection();
		String sql = "insert into orders values(seq.nextval,?,?,?)";
		String sqlstr = "select price,pstore from phone where pid =?";	
		String updateSQL = "update phone set pstore=? where pid=?";
		PreparedStatement ps = null;		
		try {		
			conn.setAutoCommit(false);
			PreparedStatement pst = conn.prepareStatement(sqlstr);
			pst.setInt(1, phoneid);
			PreparedStatement ps1 = conn.prepareStatement(updateSQL);
			ResultSet rs = pst.executeQuery();
		
			ps = conn.prepareStatement(sql);
			if(rs.next()) {
				ps.setInt(1, phoneid);
				ps.setInt(2, amount);
				if(amount>0 && amount < rs.getInt("pstore")) {
					ps.setInt(3, rs.getInt("price")*amount);
				}else {
					System.out.println("该手机库存不足！");
					return;
				}
				if(rs.getInt("pstore") > amount) {
					ps1.setInt(1, rs.getInt("pstore")-amount);
				}else {
					System.out.println("该手机库存不足！");
					return;
				}
				ps1.setInt(2, phoneid);
				System.out.println("下单完成！");
				ps.executeUpdate();
				ps1.executeUpdate();
				conn.commit();				//手动提交
				conn.setAutoCommit(true);  //恢复自动提交	
			}else {
				System.out.println("输入的手机id不正确！");
				return;
			}
		} catch (SQLException e) {
			try {
				System.out.println("出现错误，数据回滚");
				conn.rollback();
			} catch (SQLException e1) {
				e1.printStackTrace();
			}
		} finally {
			DBUtil.close(ps);
		}
	}
	
	public static void xls(String querySql) {
		 try {
			 File file = new File("D://phone.xls");
			 if (!file.exists()) {
				file.createNewFile();
			 }
			 WritableWorkbook wwb = Workbook.createWorkbook(file);
			 WritableSheet ws = wwb.createSheet("phone", 1);
			 Label lable1 = new Label(0, 0, "pid");
			 Label lable2 = new Label(1, 0, "pmodel");
			 Label lable3 = new Label(2, 0, "price");
			 Label lable4 = new Label(3, 0, "pstore");
			 ws.addCell(lable1);
			 ws.addCell(lable2);
			 ws.addCell(lable3);
			 ws.addCell(lable4);
			 
			 Connection  conn = DBUtil.getConnection();
			 PreparedStatement ps = conn.prepareStatement(querySql);
			 ResultSet rs = ps.executeQuery();
			 
			 int total = getTotal(querySql);  //总记录数
			 
			 	for (int i = 1; i <= total; i++) {
					 if(rs.next()) {
						 ws.addCell(new Number(0,i,rs.getInt("pid")));
						 ws.addCell(new Label(1,i,rs.getString("pmodel")));
						 ws.addCell(new Number(2,i,rs.getInt("price")));
						 ws.addCell(new Number(3,i,rs.getInt("pstore")));
					 }
			 }
			 wwb.write();//写入文件
			wwb.close();//关闭流
			System.out.println("文件信息写入成功！");
			} catch (Exception e) {
				e.printStackTrace();
			}
	}
	
	
}

页的类和连接数据库的类在前几篇文章中，不再重复写!