jsp页面：<%@ page language="java" contentType="text/html; charset=utf-8"%><%@ page import="dao.TDao" %><!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></head><body> <% TDao t=new TDao(); out.print(t.getLastDate()); %></body></html>DBHelper.javapackage tools;import java.sql.Connection;import java.sql.DriverManager;import java.sql.SQLException;public class DBHelper { private static String driver="com.mysql.jdbc.Driver"; private static String username="root"; private static String password="root"; private static String url="jdbc:mysql://localhost:3306/datamanagement"; private static Connection conn=null; static { try { Class.forName(driver); } catch (ClassNotFoundException e) { // TODO Auto-generated catch block e.printStackTrace(); } } public static Connection getConnection() { if(conn==null) { try { conn=DriverManager.getConnection(url,username,password); } catch (SQLException e) { // TODO Auto-generated catch block e.printStackTrace(); } return conn; }else { return null; } } public static void main(String[] args) { Connection conn=DBHelper.getConnection(); if(conn==null) { System.out.println("连接失败"); }else { System.out.println("连接成功!!!"); } }}TDao.javapackage dao;import java.sql.Connection;import java.sql.PreparedStatement;import java.sql.ResultSet;import tools.DBHelper;public class TDao { public String getLastDate() { String lastDate=null; PreparedStatement stmt=null; ResultSet rs=null; try { Connection conn=DBHelper.getConnection(); String sql="select riqi from daily_report order by riqi desc"; stmt=conn.prepareStatement(sql); rs=stmt.executeQuery(); rs.next(); lastDate=rs.getString("riqi"); }catch(Exception e) { e.printStackTrace(); }finally { try { rs.close(); stmt.close(); }catch(Exception e) { e.printStackTrace(); } } return lastDate; } public static void main(String[] args) { TDao t=new TDao(); System.out.println(t.getLastDate()); }}
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