Java中使用JDBC查询数据库指定数据-优快云博客

/**
     * 测试数据库查询功能
     * 该方法用于测试从用户表中根据用户名和密码查询用户信息的功能
     *
     * @throws Exception 当数据库连接或SQL执行过程中发生错误时抛出异常
     */
    @Test
    public void testSelect() throws Exception {
        //1.注册驱动
        Class.forName("com.mysql.cj.jdbc.Driver");
        String url="jdbc:mysql://localhost:3306/db02";
        String username="root";
        String password="123456";

        //2. 获取连接
        Connection conn = DriverManager.getConnection(url, username, password);
        // 创建预编译的PreparedStatement对象
        PreparedStatement pstmt = conn.prepareStatement("SELECT * FROM user WHERE username = ? AND password = ?");// 预编译SQL
        // 设置参数
        pstmt.setString(1, "daqiao"); // 第一个问号对应的参数
        pstmt.setString(2, "123456"); // 第二个问号对应的参数
        //3. 执行查询
        ResultSet rs = pstmt.executeQuery();
        // 处理结果集
        while (rs.next()) {
            int id = rs.getInt("id");
            String uName = rs.getString("username");
            String pwd = rs.getString("password");
            String name = rs.getString("name");
            int age = rs.getInt("age");

            System.out.println("ID: " + id + ", Username: " + uName + ", Password: " + pwd + ", Name: " + name + ", Age: " + age);
        }
        // 关闭资源
        rs.close();
        pstmt.close();
        conn.close();
    }