获取项目中Properties文件

private void readPropertiesByClass() {
        // 根目录是class文件所在目录,如果以 /开头从classpath目录中找db.properties;如果不以/开头从当前类所在的包中找
        InputStream inputStream = ReadPropertiesServlet.class
                .getResourceAsStream("/db.properties");
        Properties properties = new Properties();
        try {
            // 加载
            properties.load(inputStream);
            // getProperty()方法内部调用get()并将返回结果包装成String类型
            String name = properties.getProperty("name");
            System.out.println(name);
            System.out.println(properties.get("name"));// 返回Object类型
            // 失败，因为写入properties文件中的数据是以String类型存储的
            // int i = (int)properties.get("password");
            // System.out.println(i + 1);
        } catch (IOException e) {
            e.printStackTrace();
        }
    }

private void readPropertiesByServletContext() {
        // ServletContext方法读取配置 / 代表WebProject工程名,同级不需‘/‘
        ServletContext servletContext = getServletContext();
        InputStream inputStream = servletContext.getResourceAsStream("db.properties");
        Properties properties = new Properties();
        try {
            properties.load(inputStream);
            System.out.println(properties.getProperty("name"));
            System.out.println(properties.getProperty("password"));
        } catch (IOException e) {
            e.printStackTrace();
        }
    }

private void readPropertiesByClassLoader() {
        // 使用ClassLoader加载配置文件
        // 项目目录： web3\WEB-INF\classes
        ClassLoader classLoader = ReadPropertiesServlet.class.getClassLoader();
        // 上级目录：../
        InputStream inputStream = classLoader
                .getResourceAsStream("../../db.properties");
        // 获取Properties实例的两种方法
        // Properties properties = new Properties();
        Properties properties = System.getProperties();
        try {
            properties.load(inputStream);
            System.out.println(properties.getProperty("name"));
        } catch (IOException e) {
            e.printStackTrace();
        }
    }