String agent = request.getHeader("user-agent");
System.out.println(agent);
StringTokenizer st = new StringTokenizer(agent,";");
st.nextToken();
String userbrowser = st.nextToken();
System.out.println(userbrowser);
String useros = st.nextToken();
System.out.println(useros);
System.out.println(System.getProperty("os.name")); //win2003竟然是win xp？
System.out.println(System.getProperty("os.version"));
System.out.println(System.getProperty("os.arch"));
System.out.println(request.getHeader("user-agent")); //返回客户端浏览器的版本号、类型
System.out.println(request.getMethod()); //：获得客户端向服务器端传送数据的方法有get、post、put等类型
System.out.println(request.getRequestURI()); //：获得发出请求字符串的客户端地址
System.out.println(request.getServletPath()); //：获得客户端所请求的脚本文件的文件路径
System.out.println(request.getServerName()); //：获得服务器的名字
System.out.println(request.getServerPort()); //：获得服务器的端口号
System.out.println(request.getRemoteAddr()); //：获得客户端的ip地址
System.out.println(request.getRemoteHost()); //：获得客户端电脑的名字，若失败，则返回客户端电脑的ip地址
System.out.println(request.getProtocol()); //：
System.out.println(request.getHeaderNames()); //：返回所有request header的名字，结果集是一个enumeration（枚举）类的实例
System.out.println("Protocol: " + request.getProtocol());
System.out.println("Scheme: " + request.getScheme());
System.out.println("Server Name: " + request.getServerName() );
System.out.println("Server Port: " + request.getServerPort());
System.out.println("Protocol: " + request.getProtocol());
System.out.println("Server Info: " + getServletConfig().getServletContext().getServerInfo());
System.out.println("Remote Addr: " + request.getRemoteAddr());
System.out.println("Remote Host: " + request.getRemoteHost());
System.out.println("Character Encoding: " + request.getCharacterEncoding());
System.out.println("Content Length: " + request.getContentLength());
System.out.println("Content Type: "+ request.getContentType());
System.out.println("Auth Type: " + request.getAuthType());
System.out.println("HTTP Method: " + request.getMethod());
System.out.println("Path Info: " + request.getPathInfo());
System.out.println("Path Trans: " + request.getPathTranslated());
System.out.println("Query String: " + request.getQueryString());
System.out.println("Remote User: " + request.getRemoteUser());
System.out.println("Session Id: " + request.getRequestedSessionId());
System.out.println("Request URI: " + request.getRequestURI());
System.out.println("Servlet Path: " + request.getServletPath());
System.out.println("Accept: " + request.getHeader("Accept"));
System.out.println("Host: " + request.getHeader("Host"));
System.out.println("Referer : " + request.getHeader("Referer"));
System.out.println("Accept-Language : " + request.getHeader("Accept-Language"));
System.out.println("Accept-Encoding : " + request.getHeader("Accept-Encoding"));
System.out.println("User-Agent : " + request.getHeader("User-Agent"));
System.out.println("Connection : " + request.getHeader("Connection"));
System.out.println("Cookie : " + request.getHeader("Cookie"));

获得user-agent的值

在 ASP.NET 中使用 Request.Header["User-Agent"] 得到浏览器的 User Agent，也可以使用 Request.UserAgent 来获取；
Java 中使用 request.getHeader(”User-Agent”) 来获得；
PHP 中相应使用：$_SERVER[HTTP_USER_AGENT]；

JS中则使用navigator.userAgent来获得（客户端经常使用它来做浏览器兼容）。