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The Java Developers Almanac 1.4Order this book from Amazon. |
e1042. Getting the Requesting URL in a ServletA servlet container breaks up the requesting URL into convenient components for the servlet. The standard API does not require the original requesting URL to be saved and therefore it is not possible to get the requesting URL exactly as the client sent it. However, a functional equivalent of the original URL can be constructed. The following example assumes the original requesting URL is:http://hostname.com/mywebapp/servlet/MyServlet/a/b;c=123?d=789The most convenient method for reconstructing the original URL is to use ServletRequest.getRequestURL() , which returns all but the
query string. Adding the query string reconstructs an equivalent of
the original requesting URL:
// http://hostname.com/mywebapp/servlet/MyServlet/a/b;c=123?d=789 public static String getUrl(HttpServletRequest req) { String reqUrl = req.getRequestURL().toString(); String queryString = req.getQueryString(); // d=789 if (queryString != null) { reqUrl += "?"+queryString; } return reqUrl; }If the hostname is not needed, ServletRequest.getRequestURI()
should be used:
// /mywebapp/servlet/MyServlet/a/b;c=123?d=789 public static String getUrl2(HttpServletRequest req) { String reqUri = req.getRequestURI().toString(); String queryString = req.getQueryString(); // d=789 if (queryString != null) { reqUri += "?"+queryString; } return reqUri; }The original URL can also be reconstructed from more basic components available to the servlet: // http://hostname.com:80/mywebapp/servlet/MyServlet/a/b;c=123?d=789 public static String getUrl3(HttpServletRequest req) { String scheme = req.getScheme(); // http String serverName = req.getServerName(); // hostname.com int serverPort = req.getServerPort(); // 80 String contextPath = req.getContextPath(); // /mywebapp String servletPath = req.getServletPath(); // /servlet/MyServlet String pathInfo = req.getPathInfo(); // /a/b;c=123 String queryString = req.getQueryString(); // d=789 // Reconstruct original requesting URL String url = scheme+"://"+serverName+":"+serverPort+contextPath+servletPath; if (pathInfo != null) { url += pathInfo; } if (queryString != null) { url += "?"+queryString; } return url; }
e1041. Preventing Concurrent Requests to a Servlet e1043. Getting a Request Header in a Servlet e1044. Processing a HEAD Request in a Servlet e1045. Getting the Client's Address in a Servlet © 2002 Addison-Wesley. |