ServletContext

1、作用
解决不同用户之间数据共享问题
2、特点

  • 由服务器创立
  • 所有用户共享同一个ServletContext对象
  • 所有的Servlet都能够拜访到ServletContext中的属性
  • 每一个web我的项目对应的是一个ServletContext

3、 用法

public class ContextServlet extends HttpServlet {    protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {        this.doGet(request,response);    }    protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {        //3种形式获取ServletContext对象        ServletContext sc1 = this.getServletContext();//罕用        ServletContext sc2 = this.getServletConfig().getServletContext();        ServletContext sc3 = request.getSession().getServletContext();        //设置属性        sc1.setAttribute("name","zhangsan");    }}
public class ContextServlet2 extends HttpServlet {    protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {        this.doGet(request,response);    }    protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {        //获取ServletContext对象        ServletContext sc = this.getServletContext();        //获取在contextServlet类中设置的属性        String name = (String) sc.getAttribute("name");        System.out.println(name);//zhangsan    }}