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。
源代码:
1.DB.java
package demo; import java.sql.Connection; import java.sql.DriverManager; import java.sql.PreparedStatement; import java.sql.ResultSet; import java.sql.SQLException; 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) { e.printStackTrace(); } } public DB() { try { con = DriverManager.getConnection("jdbc:mysql://localhost:3306/db","root",""); } catch (SQLException e) { 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) { } 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]); } } n = pre.executeUpdate(); public void close() { try { if (rs != null) { rs.close(); } pre.close(); con.close(); } catch (SQLException e) { e.printStackTrace(); } } }
2.test.java
package demo; import java.sql.ResultSet; import java.sql.SQLException; import java.util.Scanner; import demo.DB; public class re { public static void main(String[] args) { Scanner input=new Scanner(System.in); String username=input.next(); String password=input.next(); ResultSet a; ResultSet b; DB db = new DB(); a = db.executeSelect("select * from t_login where username = '"+username+"' and password = '"+password+"'", args); try { if (a.next()) { System.out.println("登录成功"); System.out.println("以下为t_user表中的信息:"); int id = b.getInt(1); String name = b.getString(2); int sex = b.getInt(3); String birthday = b.getString(4); System.out.println("id:"+id+" name:"+name+" sex:"+sex+" birthday:"+birthday); } System.out.println("请输入插入信息:"); int id1 = input.nextInt(); String name1 = input.next(); int sex1 = input.nextInt(); String date1 = input.next(); String sql="insert into t_user(id,name,sex,birthday) values("+id1+",'"+name1+"',"+sex1+",'"+date1+"')"; int n = db.executeModify(sql, args); if(n>0) { System.out.println("插入成功"); }else { System.out.println("插入失败"); } }else { System.out.println("登陆失败"); } } catch (SQLException e) { e.printStackTrace(); } } }
运行结果: