在Servlet中獲取來源URL，即發送當前請求的URL。比如從a.jsp進入Servlet，在Servlet中可以獲得a.jsp的路徑。以下是代碼：
1 public void doGet(HttpServletRequest request, HttpServletResponse response) 2 throws ServletException, IOException { 3 request.setCharacterEncoding("utf-8"); 4 response.setContentType("text/html;charset=utf-8"); 5 PrintWriter out = response.getWriter(); 6 out.println("<!DOCTYPE HTML PUBLIC \"-//W3C//DTD HTML 4.01 Transitional//EN\">"); 7 out.println("<HTML>"); 8 out.println(" <HEAD><TITLE>請求來源</TITLE></HEAD>"); 9 out.println(" <BODY>"); 10 String fromURL = request.getHeader("Referer"); 11 out.print("來源於："+fromURL); 12 StringBuffer requestURL = request.getRequestURL(); 13 String queryString = request.getQueryString(); 14 if(queryString != null){ 15 requestURL .append("?").append(queryString); 16 } 17 out.print("<br />請求："+requestURL.toString()); 18 out.println(" </BODY>"); 19 out.println("</HTML>"); 20 out.flush(); 21 out.close(); 22 }
從代碼中可以看出獲取來源URL，是通過獲取HTTP頭的方式得到的,代碼中String fromURL = request.getHeader("Referer"); 語句。而request.getRequestURL()是獲取請求的URL，不包括參數。request.getQueryString()用於獲取參 數信息。
以下附錄在編程常要獲取的,包括獲取一些常用的HTTP頭：
1 out.println("Protocol: " + request.getProtocol()); 2 out.println("Scheme: " + request.getScheme()); 3 out.println("Server Name: " + request.getServerName() ); 4 out.println("Server Port: " + request.getServerPort()); 5 out.println("Protocol: " + request.getProtocol()); 6 out.println("Server Info: " + getServletConfig().getServletContext().getServerInfo()); 7 out.println("Remote Addr: " + request.getRemoteAddr()); 8 out.println("Remote Host: " + request.getRemoteHost()); 9 out.println("Character Encoding: " + request.getCharacterEncoding()); 10 out.println("Content Length: " + request.getContentLength()); 11 out.println("Content Type: "+ request.getContentType()); 12 out.println("Auth Type: " + request.getAuthType()); 13 out.println("HTTP Method: " + request.getMethod()); 14 out.println("Path Info: " + request.getPathInfo()); 15 out.println("Path Trans: " + request.getPathTranslated()); 16 out.println("Query String: " + request.getQueryString()); 17 out.println("Remote User: " + request.getRemoteUser()); 18 out.println("Session Id: " + request.getRequestedSessionId()); 19 out.println("Request URI: " + request.getRequestURI()); 20 out.println("Servlet Path: " + request.getServletPath()); 21 out.println("Accept: " + request.getHeader("Accept")); 22 out.println("Host: " + request.getHeader("Host")); 23 out.println("Referer : " + request.getHeader("Referer")); 24 out.println("Accept-Language : " + request.getHeader("Accept-Language")); 25 out.println("Accept-Encoding : " + request.getHeader("Accept-Encoding")); 26 out.println("User-Agent : " + request.getHeader("User-Agent")); 27 out.println("Connection : " + request.getHeader("Connection")); 28 out.println("Cookie : " + request.getHeader("Cookie")); 29 out.println("Created : " + session.getCreationTime()); 30 out.println("LastAccessed : " + session.getLastAccessedTime());