Knowledgebase: Java/JSP Hosting Plans
Getting the Requesting URL in a Servlet
Posted by Customer Service on 25 May 2005 12:47 AM
A 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=789
The 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;
}
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