@Test
public void testDriver() throws SQLException {

    //1. 创建一个 Driver 实现类的对象

    Driver driver = new com.mysql.jdbc.Driver();

    //2. 准备连接数据库的基本信息: url, user, password

    String url = "jdbc:mysql://localhost:3306/test";

    Properties info = new Properties();

    info.put("user", "root");

    info.put("password", "1230");

    //3. 调用 Driver 接口的　connect(url, info) 获取数据库连接

    Connection connection = driver.connect(url, info);

    System.out.println(connection);
}

/**
JDBC.properties文件中的内容：

#driver=oracle.jdbc.driver.OracleDriver
#jdbcUrl=jdbc:oracle:thin:@localhost:1521:orcl
#user=scott
#password=java

driver=com.mysql.jdbc.Driver
jdbcUrl=jdbc:mysql://localhost:3306/atguigu
user=root
password=1230
*/

public Connection getConnection() throws Exception{

    String driverClass = null;
    String jdbcUrl = null;
    String user = null;
    String password = null;

    //读取类路径下的 jdbc.properties 文件
    InputStream in = 
            getClass().getClassLoader().getResourceAsStream("jdbc.properties");
    Properties properties = new Properties();
    properties.load(in);
    driverClass = properties.getProperty("driver");
    jdbcUrl = properties.getProperty("jdbcUrl");
    user = properties.getProperty("user");
    password = properties.getProperty("password");

    //通过反射常见 Driver 对象. 
    Driver driver = 
            (Driver) Class.forName(driverClass).newInstance();
    Properties info = new Properties();
    info.put("user", user);
    info.put("password", password);

    //通过 Driver 的 connect 方法获取数据库连接. 

    Connection connection = driver.connect(jdbcUrl, info);
    return connection;
    }

    @Test
    public void testGetConnection() throws Exception{
        System.out.println(getConnection());
    }