springmvc 退出清除session，返回首页，获取当前项目路径，返回前台ajax输出 东师理想

@RequestMapping(value="/logout",method=RequestMethod.GET)
       public void logout(HttpServletRequest request,HttpServletResponse response)
       {
           //清除session
        Enumeration<String> em = request.getSession().getAttributeNames();
        while(em.hasMoreElements()){
            request.getSession().removeAttribute(em.nextElement().toString());
        }
        request.getSession().invalidate();
        //获取项目真实路径 
           String path = request.getContextPath();
          //拼接跳转页面路径
           String basePath = request.getScheme() + "://"
                  + request.getServerName() + ":" + request.getServerPort()
                  + path + "/";
          //刷新页面
        String str = "<script>top.location='"+basePath+"'</script>";
        System.out.println(str);
        responseTxt(response,str); 
       }

//返回前台页面ajax
protected void responseTxt(HttpServletResponse response,String str){
        try {
            response.setContentType("text/html;charset=UTF-8");
            PrintWriter out = response.getWriter();
            out.write(str);
            out.flush();
            out.close();
        } catch (Exception e) {
            e.printStackTrace();
        }        
    }