JSF redirect exception

Question

When navigating from the login page of my portal to the index page, there is a situation when based on some facts the user can be redirected externally, which looks like:

if (!(marketVo.getAbsoluteUrl() != null && marketVo.getAbsoluteUrl().equals(absoluteUrlToRedirect))) {
logger.info("---WILL REDIRECT TO ABS URL: " + absoluteUrlToRedirect);
final FacesContext context = FacesContext.getCurrentInstance();
context.responseComplete();
try {
    final HttpServletResponse response = (HttpServletResponse) context.getExternalContext().getResponse();

    if (context.getViewRoot() != null) {
        // this step will clear any queued events
        context.getViewRoot().processDecodes(context);
    }
    response.sendRedirect(absoluteUrlToRedirect);

} catch (final Exception e) {
    // TODO Auto-generated catch block
    e.printStackTrace();
}

}

Well, it throws an exception:

 14:24:35,579 INFO  [CmwSessionHelperBean] ---WILL REDIRECT TO ABS URL: http://hi
tachi.mygravitant.com
14:24:35,580 ERROR [STDERR] java.lang.IllegalStateException
14:24:35,582 ERROR [STDERR]     at org.apache.catalina.connector.ResponseFacade.
sendRedirect(ResponseFacade.java:435)
14:24:35,590 ERROR [STDERR]     at com.example.cloud.common.jsf.core.beans.Cmw
SessionHelperBean.createCmwUserSession(CmwSessionHelperBean.java:269)

Can you please give me a suggestion to avoid this exception to occure? Please note that the redirect is done, but because of this exception, when I come back to my portal, it is no longer working properly...

Answer 1

You should be using ExternalContext#redirect() to perform a redirect in a JSF-safe way.

public void createCmwUserSession() throws IOException {

    if (!(marketVo.getAbsoluteUrl() != null && marketVo.getAbsoluteUrl().equals(absoluteUrlToRedirect))) {
        logger.info("---WILL REDIRECT TO ABS URL: " + absoluteUrlToRedirect);
        FacesContext.getCurrentInstance().getExternalContext().redirect(absoluteUrlToRedirect);
    }
}

This method will also implicitly call FacesContext#responseComplete(), you don't need to do it yourself.

Further you need to make sure that you are not calling the redirect method multiple times on the same response, or are performing a navigation afterwards.