十五次作业
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。
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。
package 刘磊的作业; import java.sql.ResultSet; import java.sql.SQLException; import java.util.Scanner; /** * 测试类 * */ public class Test { public static void main(String[] args) { MysqlDataBase db = MysqlDataBase.getInstance(); boolean flag = false; Scanner scanner = new Scanner(System.in); String username = scanner.next(); String passward = scanner.next(); String sql = "SELECT * FROM t_login where username = ? AND password=?"; ResultSet rs = db.DBQuery(sql, new Object[]{username,passward}); try { if (rs.next()) { System.out.println("登录成功!"); flag = true; } } catch (SQLException e) { e.printStackTrace(); } if (flag) { sql = "select id,name,sex,birthday from t_user"; rs = db.DBQuery(sql, new Object[]{}); try { while (rs.next()) { System.out.print(rs.getInt(1)); System.out.print(" "); System.out.print(rs.getString(2)); System.out.print(" "); if(rs.getInt(3)==0) System.out.print("男"); else System.out.println("女"); System.out.print(" "); System.out.println(rs.getString(4)); } } catch (SQLException e) { e.printStackTrace(); } String name = "刘磊1"; int sex = 0; String date = "2012-01-01"; sql = "insert into t_user (name,sex,birthday)values(?,?,?)"; if (db.DBModify(sql, new Object[] { name, sex, date }) > 0) { System.out.println("更新成功"); } else { System.out.println("数据未更新"); } } } }
package 刘磊的作业; import java.sql.Connection; import java.sql.DriverManager; import java.sql.PreparedStatement; import java.sql.ResultSet; import java.sql.SQLException; /** * *MySQL数据库链接类 */ public class MysqlDataBase { private static MysqlDataBase db; private Connection con; private PreparedStatement ps; private ResultSet rs; static { try { Class.forName("com.mysql.cj.jdbc.Driver"); } catch (ClassNotFoundException e) { e.printStackTrace(); } } public static MysqlDataBase getInstance() { if (db == null) { db = new MysqlDataBase(); } return db; } private MysqlDataBase() { try { con = DriverManager.getConnection("jdbc:mysql://localhost:3306/liulei?serverTimezone=UTC", "root", ""); } catch (SQLException e) { e.printStackTrace(); } } public ResultSet DBQuery(String sql, Object[] field) { try { ps = con.prepareStatement(sql); if (field.length > 0) { for (int i = 0; i < field.length; i++) { ps.setObject(i + 1, field[i]); } } rs = ps.executeQuery(); } catch (SQLException e) { e.printStackTrace(); } return rs; } public int DBModify(String sql, Object[] field) { int n = 0; try { ps = con.prepareStatement(sql); if (field.length > 0) for (int i = 0; i < field.length; i++) { ps.setObject(i + 1, field[i]); } n = ps.executeUpdate(); } catch (SQLException e) { e.printStackTrace(); } return n; } public void close() { try { if (rs != null) { rs.close(); } ps.close(); con.close(); } catch (SQLException e) { e.printStackTrace(); } } }