@Test
    public void testConnection1() throws SQLException {
        // 获取Driver实现类对象
        Driver driver = new com.mysql.cj.jdbc.Driver();
        // jdbc:mysql协议
        // localhost:ip地址
        // 3306:默认的mysql的端口号
        // school：数据库
        String url = "jdbc:mysql://localhost:3306/school";
        // 将用户名和密码封装在Properties中
        Properties info = new Properties();
        info.setProperty("user", "root");
        info.setProperty("password", "xxx");
        Connection connection = driver.connect(url, info);
        System.out.println(connection);
    }

/*
     * 是程序更具有可移植性 利用反射
     */
    @Test
    public void testConnection2() throws Exception {
        // 获取Driver实现类对象
        Class clazz = Class.forName("com.mysql.jdbc.Driver");
        // newInstance需要拥有空参构造器
        Driver driver = (Driver) clazz.newInstance();
        // 提供要连接的数据库
        String url = "jdbc:mysql://localhost:3306/school";
        // 提供连接需要的用户名和密码
        Properties properties = new Properties();
        properties.setProperty("user", "root");
        properties.setProperty("password", "xxx");
        // 获取连接
        Connection connect = driver.connect(url, properties);
        System.out.println(connect);

    }

// 方式三使用DriverManager来代替Driver
    @Test
    public void testConnection3() throws Exception {
        // 获取Driver实现类对象
        Class clazz = Class.forName("com.mysql.cj.jdbc.Driver");
        Driver driver = (Driver) clazz.newInstance();
        // 提供另外三个连接的基本信息
        String url = "jdbc:mysql://localhost:3306/school";
        String user = "root";
        String password = "xxx";
        // 注册驱动
        DriverManager.registerDriver(driver);
        // 获取连接
        Connection connection = DriverManager
                .getConnection(url, user, password);
        System.out.println(connection);

    }

// 方式四只用加载驱动不用显示的注册驱动
    @Test
    public void testConection4() throws Exception{
        // 加载Driver
        Class.forName("com.mysql.cj.jdbc.Driver");
        
        // 提供另外三个连接的基本信息
        String url = "jdbc:mysql://localhost:3306/school";
        String user = "root";
        String password = "xxx";
        //省略如下操作，
        /*// 注册驱动
        DriverManager.registerDriver(driver);*/
        // 获取连接
        Connection connection = DriverManager
                .getConnection(url, user, password);
        System.out.println(connection);
    }

static  {
     try {
     DriverManager.registerDriver(new Driver());
   } catch (SQLException E) {
       throw new RuntimeException("Can‘t register driver!");
     } 
   }

//实现数据和代码的分离。实现了解耦
    //方式五：将数据库需要的四个基本信息声明在配置文件中，通过读取配置文件获取连接
    @Test
    public void testConection5() throws Exception{
        //读取配置文件的基本信息
        InputStream is = ConnectionTest.class.getClassLoader().getResourceAsStream("jdbc.properties");
        Properties properties = new Properties();
        properties.load(is);
        String user = properties.getProperty("user");
        String password = properties.getProperty("password");
        String url = properties.getProperty("url");
        String driverClass = properties.getProperty("driverClass");
        //加载驱动
        Class.forName(driverClass);
        //获取连接
        Connection connection = DriverManager.getConnection(url, user, password);
        System.out.println(connection);
        
    }