jdbc固定使用

1.加载驱动；2.连接数据库；3.向数据库发送SQL的对象statement：CRUD；4.编写SQL（不同的查询，要用不同的sql语句）；5.执行SQL;6.关闭连接

<!--        mysql的驱动-->
     <dependency>
            <groupId>mysql</groupId>
            <artifactId>mysql-connector-java</artifactId>
            <version>5.1.47</version>
        </dependency>
    </dependencies>

连接数据库代码：

    //配置信息
    //useUnicode=true&characterEncoding=utf-8用来解决中文乱码
    String url = "jdbc:mysql://localhost:3306/jdbc?useUnicode=true&characterEncoding=utf-8";
    String username = "root";
    String password = "123456";

    //1.加载驱动
    Class.forName("com.mysql.jdbc.Driver");
    //2.连接数据库，代表数据库
    Connection connection = DriverManager.getConnection(url, username, password);
    //3.向数据库发送SQL的对象Statement  ：增删改查
    Statement statement = connection.createStatement();
    //4.编写SQL
    String sql = "select * from users;";
    //5.执行SQL语句，返回一个ResultSet   ：结果集
    ResultSet rs = statement.executeQuery(sql);
    //输出结果集里面的数据
    while(rs.next()){
        System.out.println("id:" + rs.getObject("id"));
        System.out.println("name:" + rs.getObject("name"));
        System.out.println("password:" + rs.getObject("password"));
        System.out.println("email:" + rs.getObject("email"));
        System.out.println("birthday:" + rs.getObject("birthday"));
        System.out.println("=========================");
    }
    //6.关闭连接，释放资源（一定要做），先开的最后关
    rs.close();
    statement.close();
    connection.close();
}