如何获取客户端IP、操作系统、浏览器

request.getRemoteAddr();//获取IP

request.getHeader("User-Agent");//获取操作系统信息、浏览器信息。

     protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
 //        response.sendError(404, "不给看");//设置状态码
 //        response.setHeader("Location", "/Servlet/BServlet");//重定向
 //        response.sendError(302);
         request.setCharacterEncoding("utf-8");
         response.setContentType("text/html;charset=utf-8");

 //        PrintWriter p = response.getWriter();
 //        p.write("5秒钟后自动跳转！");
 //        response.setHeader("refresh", "5;url=/Servlet/BServlet");//定时器
         System.out.println(request.getRemoteAddr());
         String userAgent =request.getHeader("User-Agent");
         if(userAgent.toLowerCase().contains("firefox")){
             System.out.println("火狐");
         }else if(userAgent.toLowerCase().contains("chrome")){
             System.out.println("谷歌");
         }else if(userAgent.toLowerCase().contains("msie")){
             System.out.println("ie");
         }

     }