<servlet><!--servlet注册的名字--><servlet-name>HelloServlet</servlet-name><!--servlet的全类名--><servlet-class>com.demo.javaweb.HelloServlet</servlet-class><!--配置servlet的初始化参数 且节点必须在load-on-startup节点的前面--><init-param><!--参数名--><param-name>user</param-name><!--参数值--><param-value>root</param-value></init-param><init-param><param-name>password</param-name><param-value>1230</param-value></init-param><!--可以指定Servlet被创建的时机--><load-on-startup>1</load-on-startup></servlet>

 @Overridepublic void init(ServletConfig servletConfig) throws ServletException {System.out.println("init...");String user = servletConfig.getInitParameter("user");System.out.println(user);Enumeration<String> names = servletConfig.getInitParameterNames();while (names.hasMoreElements()){String name = names.nextElement();String value = servletConfig.getInitParameter(name);System.out.println(name + " " + value);}}

 String servletName = servletConfig.getServletName();System.out.println(servletName);

  <!--配置当前WEB应用的初始化参数--><context-param><param-name>driver</param-name><param-value>com.mysql.jdbc.Driver</param-value></context-param><context-param><param-name>jdbcUrl</param-name><param-value>jdbc:mysql://</param-value></context-param>

        ServletContext servletContext = servletConfig.getServletContext();String driver = servletContext.getInitParameter("driver");System.out.println(driver);Enumeration<String> names2 = servletContext.getInitParameterNames();while (names2.hasMoreElements()){String name = names2.nextElement();String value = servletConfig.getInitParameter(name);System.out.println(name + " " + value);}

        String realPath = servletContext.getRealPath("/hello.jsp");System.out.println(realPath);

   　　　ClassLoader classLoader = getClass().getClassLoader();InputStream is = classLoader.getResourceAsStream("jdbc.properties");System.out.println(is);InputStream inputStream = servletContext.getResourceAsStream("/WEB-INF/classes/jdbc.properties");System.out.println(inputStream);