自学Servlet_2_servletContext(2)

读取配置文件的各种方法：
方法一：

		ServletContext context = this.getServletContext();
		InputStream in = context.getResourceAsStream("/db.properties");

		Properties prop = new Properties();  //map
		prop.load(in);


		String url = prop.getProperty("url");
		String username = prop.getProperty("username");
		String password = prop.getProperty("password");

		System.out.println(url);
		System.out.println(username);
		System.out.println(password);

方法二：

ServletContext context = this.getServletContext();
		String realpath = context.getRealPath("/db.properties");  //c:\\sdsfd\sdf\db.properties

		//获取到操作文件名   realpath=abc.properties
		String filename = realpath.substring(realpath.lastIndexOf("\\")+1);
		System.out.println("当前读到的文件是：" + filename);


		FileInputStream in = new FileInputStream(realpath);
		Properties prop = new Properties();
		prop.load(in);

		String url = prop.getProperty("url");
		String username = prop.getProperty("username");
		String password = prop.getProperty("password");

		System.out.println("文件中有如下数据：");
		System.out.println(url);
		System.out.println(username);
		System.out.println(password);

方法三：

ServletContext context = this.getServletContext();
		URL url = context.getResource("/resource/db.properties");
		InputStream in = url.openStream();

方法四：

InputStream in = this.getServletContext().getResourceAsStream("/WEB-INF/classes/db.properties");
		Properties prop = new Properties();  //map
		prop.load(in);


		String url = prop.getProperty("url");
		String username = prop.getProperty("username");
		String password = prop.getProperty("password");

		System.out.println(url);
		System.out.println(username);
		System.out.println(password);