I am working on a simple method that will assign a specific extension
(e.g. ".jsp", ".php", ".cfm", etc.) to the end of a URL if it doesn't
find anything marking a valid extension, however, I do not want to add
an extension if one is found.

Consider my code:

<code>
<pre>
import java.util.regex.Pattern;
...
public static final String urlEndSlashPattern = "/?";

public static final String urlQSPattern = "\\??([a-zA-Z0-9\\-_\\.]
+=[^&]*&?)*";

public static final String urlAnchorPattern = "#[^#]*$";

...

public static void addExtToUrl(String url, String myExt, String[]
exts) {

  StringBuffer sb = new StringBuffer();
  boolean hasExt = false;
  for (int i = 0; i < exts.length; i++) {

sb.append(".").append(exts[i]).append(urlEndSlashPattern).append(urlQSPattern).append(urlAnchorPattern);
    if (Pattern.matches(sb.toString(), url)) {
     hasExt = true;
    }
    sb = new StringBuffer();
   }
   if (!hasExt) {
    url += "." + myExt;
   }

  {code}

The issue I want to bring up is the regular expression pattern I'm
using appears to fail.  I want to check and see if the URL I provide
ends with a valid extension, followed by optional "/" or a query
string or an anchor or any combination of these.

Like say if I have

http://www.blah.com/index.html

Then don't add the ".jsp" extension

But if I have

http://www.blah.com/registration/

Then I *want* to add the ".jsp" extension:

http://www.blah.com/registration.jsp

Or if I have:

http://www.blah.com/registration/?foo=bar#baz

Then it needs to change to

http://www.blah.com/registration.jsp?foo=bar#baz

But if I have

http://www.blah.com/registration/index.php?foo=bar#baz

Then I do *not* add the ".jsp" extension.

Hope that makes sense now.  Bottom line is that the pattern above
doesn't seem to work.  Ideas?

Thanks