My JSP and Servlets professor handed me down this code as a nice way to reconstruct an original request URL and avoid the temptation to ever hard-code a URL, which is also really bad practice. It’s really useful for getting out of tricky situations. In my case, I needed a way to go back to the http:// protocol after having accessed resources using SSL. I found that if I simply used RequestDispatcher, even when the resource I was requesting wasn’t included among those restricted ones, the protocol continued to be https:// . I had searched everywhere for a way to fix this and this is what he suggested.
Example:
// 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;
}