题目1:编写一个应用程序,输入用户名和密码,访问test数据库中t_login表(字段包括id、username、password),验证登录是否成功。
题目2:在上一题基础上,当登录成功后,将t_user表(id、name、sex、birthday)的信息进行显示(要求使用DB.java完成登录和获取t_user表中数据的操作),最后再对t_user表进行一条记录的添加操作。
代码:
DB类
public class DB { private Connection con; private PreparedStatement pre; private ResultSet rs; private static DB db; static{ try { Class.forName("com.mysql.jdbc.Driver"); } catch (ClassNotFoundException e) { // TODO Auto-generated catch block e.printStackTrace(); } } DB(){ try { con = DriverManager.getConnection("jdbc:mysql://localhost:3306/db", "root", ""); } catch (SQLException e) { // TODO Auto-generated catch block e.printStackTrace(); } } public static DB getInstance(){ if(db==null){ db = new DB(); } return db; } public ResultSet executeSelect(String sql, Object[] args){ try { pre = con.prepareStatement(sql); if(args.length !=0){ for(int i=0;i<args.length;i++){ pre.setObject(i+1, args[i]); } rs = pre.executeQuery(); } } catch (SQLException e) { // TODO Auto-generated catch block e.printStackTrace(); } return rs; } public int executeModify(String sql, Object[] args){ int n=0; try { pre = con.prepareStatement(sql); if(args.length!=0){ for(int i=0;i<args.length;i++){ pre.setObject(i+1,args[i]); } } } catch (SQLException e) { // TODO Auto-generated catch block e.printStackTrace(); } return n; } public void close(){ if(rs!=null){ try { rs.close(); } catch (SQLException e) { // TODO Auto-generated catch block e.printStackTrace(); } } } }
主类
package ccut.cn; import ccut.cn.DB; import java.sql.ResultSet; import java.sql.SQLException; import java.util.Scanner; public class test { /** * @param args */ public static void main(String[] args) { // TODO Auto-generated method stub System.out.println("请输入用户名和密码:"); Scanner reader = new Scanner(System.in); String username = reader.nextLine(); double password = reader.nextDouble(); ResultSet p; ResultSet r; DB db = new DB(); p = db.executeSelect("select * from t_login where username = '"+username+"' and password = '"+password+"'", args); try { if(username.equalsIgnoreCase(username)){ System.out.println("登录成功"); r = db.executeSelect("select * from t_user", args); while(r.next()) { int id = r.getInt(1); String name = r.getString(2); int sex = r.getInt(3); String birthday =r.getString(4); System.out.println("id:"+id+"\tname:"+name+"\tsex:"+sex+"\tbirthday:"+birthday); } System.out.println("请输入需要添加的记录内容为:"); int new_id = reader.nextInt(); String newname = reader.next(); int newsex = reader.nextInt(); String newdate =reader.next(); String sql="insert into t_user(id,name,sex,birthday) values("+new_id+",'"+newname+"',"+newsex+",'"+newdate+"')"; int n =db.executeModify(sql, args); if(n>0) { System.out.println("数据插入成功"); }else { System.out.println("数据插入失败"); } } else{ System.out.println("登录失败!"); } //} //catch (ClassNotFoundException e) { // TODO Auto-generated catch block //e.printStackTrace(); }catch (SQLException e) { // TODO Auto-generated catch block e.printStackTrace(); } } }
截图