// 方式1：
    @Test
    public void testConnection1() {
        try {
            // 1.获取Driver实现类对象
            Driver driver = null;
            driver = new com.mysql.cj.jdbc.Driver();
            // 2.提供url，指明具体操作的数据
            String url = "jdbc:mysql://localhost:3306/test?characterEncoding=utf8&useSSL=false&serverTimezone=UTC&rewriteBatchedStatements=true";
            // 3.提供Properties的对象，指明用户名和密码
            Properties info = new Properties();
            info.setProperty("user", "root");
            info.setProperty("password", "abc123");
            // 4.调用driver的connect()，获取连接
            Connection conn = driver.connect(url, info);
            System.out.println(conn);
        } catch (SQLException e) {
            // TODO: handle exception
            e.printStackTrace();
        }
    }

// 方式二：对方式一的迭代在如下的程序中不出现第三方的API，使得程序具有更好的可移植性
    @Test
    public void testConnection2() {
        try {
            // 1.获取Driver实现类对象，使用反射
            Class clazz = Class.forName("com.mysql.cj.jdbc.Driver");
            Driver driver = (Driver) clazz.newInstance();
            // 2.提供要连接的数据库
            String url = "jdbc:mysql://localhost:3306/test?characterEncoding=utf8&useSSL=false&serverTimezone=UTC&rewriteBatchedStatements=true";
            // 3.提供连接需要的用户名和密码
            Properties info = new Properties();
            info.setProperty("user", "root");
            info.setProperty("password", "abc123");
            // 4.获取连接
            Connection conn = driver.connect(url, info);
            System.out.println(conn);
        } catch (Exception e) {
            // TODO: handle exception
            e.printStackTrace();
        }
    }

// 方式三：使用DriverManager替换Driver
    @Test
    public void testConnection3() {
        try {
            // 1.获取Driver实现类
            Class clazz = Class.forName("com.mysql.cj.jdbc.Driver");
            Driver driver = (Driver) clazz.newInstance();
            // 2.提供另外三个连接的基本信息
            String url = "jdbc:mysql://localhost:3306/test?characterEncoding=utf8&useSSL=false&serverTimezone=UTC&rewriteBatchedStatements=true";
            String user = "root";
            String password = "abc123";
            // 3.注册驱动
            DriverManager.registerDriver(driver);
            // 4.获取连接
            Connection connection = DriverManager.getConnection(url, user, password);
            System.out.println(connection);
        } catch (Exception e) {
            // TODO: handle exception
            e.printStackTrace();
        }
    }

// 方式四：可以只是价值取得，不用显示的注册驱动了
    @Test
    public void testConnection4() {
        try {
            // 1.提供三个连接的基本信息
            String url = "jdbc:mysql://localhost:3306/test?characterEncoding=utf8&useSSL=false&serverTimezone=UTC&rewriteBatchedStatements=true";
            String user = "root";
            String password = "abc123";
            // 2.加载Driver
            Class.forName("com.mysql.cj.jdbc.Driver");
            // 相较于方式三：可以省略如下操作
            // Driver driver = (Driver) clazz.newInstance();
            // //注册驱动
            // DriverManager.registerDriver(driver);
            // 为什么可以省略操作呢？
            /*
             * 可以注释掉上述代码的原因，是因为在mysql的Driver类中声明有： static { try {
             * DriverManager.registerDriver(new Driver()); } catch (SQLException var1) {
             * throw new RuntimeException("Can't register driver!"); } }
             */
            // 3.获取连接
            Connection connection = DriverManager.getConnection(url, user, password);
            System.out.println(connection);
        } catch (Exception e) {
            // TODO: handle exception
            e.printStackTrace();
        }
    }

// 方式五（final版）：
    @Test
    public void getConnection5() throws Exception {
        // 1.读取配置文件的4个基本信息
        InputStream is = ConnectionTest.class.getClassLoader().getResourceAsStream("jdbc.properties");
        Properties pros = new Properties();
        pros.load(is);
        String user = pros.getProperty("user");
        String password = pros.getProperty("password");
        String url = pros.getProperty("url");
        String driverClass = pros.getProperty("driverClass");
        // 2.加载驱动
        Class.forName(driverClass);
        // 3.获取连接
        Connection conn = DriverManager.getConnection(url, user, password);
        System.out.println(conn);
    }