How to recognize redirects?

[Marwan Oweis]

All,

I have a servlet (call it Servlet A) that once called opens an Http Connection on another server with another servlet (call it Servlet B). This is done using java.net.HttpURLConnection.

The URL for Servlet B actually points to a load balancer, so my request gets redirected to the appropriate host.

My question is as follows: is there a way for Servlet A to get the host or ip to which it gets redirected?

Let me give an example:
1) Servlet A opens a connection to http://www.example.com/checkExample
2) www.example.com is the host name of load balancer. It redirects the request to http://www.redirectexample.com/checkExample

Is there a way for Servlet A to recognize/figure out the redirect URL: www.redirectexample.com?



Thanks,
Marwan
SCJP5, SCWCD5
[ June 09, 2008: Message edited by: Marwan Oweis ]

[David O'Meara]

Not that I can see.

[William Brogden]

Looking at the JavaDocs it appears that setFollowRedirects is true by default. Perhaps you could set that to false and handle the new address in your code.

Bill

[Marwan Oweis]

Originally posted by William Brogden:
Looking at the JavaDocs it appears that setFollowRedirects is true by default. Perhaps you could set that to false and handle the new address in your code.

Bill

Thanks! I saw that but it never registered.

I found a code sample in the apache commons project:

public URL handleRedirects(URL url) throws IOException, MalformedURLException {
        java.net.HttpURLConnection.setFollowRedirects(false);
        HttpURLConnection con = (HttpURLConnection) url.openConnection();
        int response = con.getResponseCode();
        log.debug("Response code for " + url + " = " + response);
 
        if (response == java.net.HttpURLConnection.HTTP_MOVED_PERM || response == java.net.HttpURLConnection.HTTP_MOVED_TEMP) {
            String location = con.getHeaderField("Location");
            log.debug("Handling redirect to location: " + location);
 
            if (location.startsWith("http:")) {
                url = new URL(location);
            } else if (location.startsWith("/")) {
                url = new URL("http://" + url.getHost() + location);
            } else {
                url = new URL(con.getURL(), location);
            }
 
            url = handleRedirects(url); // to handle nested redirections
        }
 
        return url;
    }

[ June 10, 2008: Message edited by: Marwan Oweis ]