JDBC练习-登录案例

练习-登录案例

需求：

1.通过键盘录入用户名和密码

2.判断用户是否登录成功

select * from user where username="" and password="";
如果这个sql有查询结果 则成功  反之 则失败

步骤：

1.创建数据表user

sql语句

CREATE TABLE user(
        id INT PRIMARY KEY AUTO_INCREMENT,
        username VARCHAR(32),
        password VARCHAR(32)
);

INSERT INTO user VALUES(null,"zhangsan","123");
INSERT INTO user VALUES(null,"lisi","456");

 测试类

public static void main(String[] args) {
        //1.键盘录入 接受用户名和密码
        Scanner sc = new Scanner(System.in);
        System.out.println("请输入用户名:");
        String username = sc.nextLine();
        System.out.println("请输入密码:");
        String password = sc.nextLine();
        //2.调用方法
        boolean flag = new JDBCDemo07().login(username, password);
        //3.判断结果 输入不同语句
        if (flag) {
            //登录成功
            System.out.println("登录成功!");
        } else {
            System.out.println("用户名或密码错误!!!");
        }
    }

    /*
    登录方法
     */
    public boolean login(String username, String password) {
        if (username == null || password == null) {
            return false;
        }
        //连接数据库判断是否登录成功
        Connection conn = null;
        Statement stmt = null;
        //1.获取连接
        try {
            conn = JDBCUtil.getConnection();
            //2.定义sql
            String sql = "select * from user where username='" + username + "' and password='" + password + "'";
            //3.获取执行sql的对象
            stmt = conn.createStatement();
            //4.执行查询
            ResultSet rs = stmt.executeQuery(sql);
            //判断
            return rs.next();
        } catch (SQLException throwables) {
            throwables.printStackTrace();
        } finally {
            JDBCUtil.close(stmt, conn);
        }

        return false;
    }

运行结果