ServletContext

1.共享数据

ServletContext servletContext = this.getServletContext();
String username = "徐凤年";
servletContext.setAttribute("username",username);

ServletContext servletContext = this.getServletContext();
String username = (String) servletContext.getAttribute("username");
response.setContentType("text/html");
response.setCharacterEncoding("utf-8");response.getWriter().print("名字" + username);

web.xml配置文件

2.获取初始化参数

ServletContext servletContext = this.getServletContext();
String url = servletContext.getInitParameter("url");
response.getWriter().print(url);

3.ServletContext应用

4.读取资源文件

Properties
●在java目录下新建properties
●在resources目录 下新建properties
发现:都被打包到了同一个路径下: classes, 我们俗称这个路径为classpath:
思路:需要一个文件流;

db.properties

username=root
password=123456

public class ServletDemo05 extends HttpServlet {@Overrideprotected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {InputStream resourceAsStream = this.getServletContext().getResourceAsStream("/WEB-INF/classes/db.properties");Properties properties  = new Properties();properties.load(resourceAsStream);String username = properties.getProperty("username");String password = properties.getProperty("password");response.getWriter().print(username + password);}

   response.getWriter().print(username + password);
}