笔记：将配置文件加载成字节流，并获取其中资源

		//创建Properties对象
        Properties properties = new Properties();
        //获取类加载器
        ClassLoader loader = baseDao.class.getClassLoader();
        //通过类加载器加载资源文件为字节输入流
        InputStream in = loader.getResourceAsStream("db.properties");
        try {
            properties.load(in);
        } catch (IOException e) {
            e.printStackTrace();
        }
        //获取db.properties资源
        DRIVER = properties.getProperty("DRIVER");
        URL = properties.getProperty("URL");
        USERNAME = properties.getProperty("USERNAME");
        PASSWORD = properties.getProperty("PASSWORD");