我先创建了一个servelt test1

public class test1 extends HttpServlet {

         public void doGet(final HttpServletRequest request, final HttpServletResponse response)

                            throws ServletException, IOException { 

                   final String student=request.getParameter("student");

        final String teacher=request.getParameter("teacher");

        //response.setHeader("Refresh", "1");

        this.getServletContext().setAttribute("111",student+teacher);

         }

         public void doPost(HttpServletRequest request, HttpServletResponse response)

                            throws ServletException, IOException {

                   doGet(request, response);

         }

}

然后我又新建了一个servlet test4

import java.io.IOException;

import javax.servlet.ServletException;

import javax.servlet.http.HttpServlet;//引入sevlet

import javax.servlet.http.HttpServletRequest;

import javax.servlet.http.HttpServletResponse;

public class test4 extends HttpServlet {

    String value;

         public void doGet(HttpServletRequest request, HttpServletResponse response)

                            throws ServletException, IOException {

                            value=(String) this.getServletContext().getAttribute("111");//可以写在另一个servlet,也可以是同一个servlet的另一种方法中。

                       response.getOutputStream().write(value.getBytes());

         }

         public void doPost(HttpServletRequest request, HttpServletResponse response)

                            throws ServletException, IOException {

                   doGet(request,response);

                   //response.getOutputStream().write(value.getBytes());

                   //doGet(request, response);

         }

}