注意！无论是request,session,application必须先调用setAttribute得到保存作用域中保存数据request：一次请求响应范围@WebServlet("/demo01")publicclassDemo01ServletextendsHttpServlet{@Overrideprotectedvoidservice(HttpServletRequestrequest,HttpServletResponseresponse)throwsServletException,IOException{request.setAttribute("uname","request保

注意！无论是request,session,application必须先调用setAttribute得到保存作用域中保存数据request：一次请求响应范围@WebServlet("/demo01")publicclassDemo01ServletextendsHttpServlet{@Overrideprotectedvoidservice(HttpServletRequestrequest,HttpServletResponseresponse)throwsServletException,IOException{request.setAttribute("uname","request保