NOTE: This is outdated information that applies only to Tapestry 3 and 4. For current information see Tapestry5RedirectException.

Easy Browser Redirection

A common problem is the need to redirect the browser from a Tapestry Listener. The way this is accomplished is with the following steps.

  1. Find the Tapestry service you want
  2. Use the getLink() method with the right parameters in the right order
  3. Thow a RedirectException

The following extended RedirectException makes this very easy. Thanks to Paul Ferraro for posting this gem to the mailing list.

Example (Tapestry3)

import org.apache.tapestry.IDirect;
import org.apache.tapestry.IRequestCycle;
import org.apache.tapestry.RedirectException;
import org.apache.tapestry.Tapestry;
import org.apache.tapestry.engine.ILink;
import org.apache.tapestry.link.DirectLink;

public class TapestryRedirectException extends RedirectException {

	private static final long serialVersionUID = 4049918285694842678L;

    public TapestryRedirectException(String url)
    {
        super(url);
    }
   
    public TapestryRedirectException(ILink link)
    {
        this(link.getURL());
    }
   
    /**
     * Use this to redirect the browser to the specified page
     */
    public TapestryRedirectException(IRequestCycle cycle, String page)
    {
        this(cycle.getEngine().getService(Tapestry.PAGE_SERVICE).getLink(cycle, 
          cycle.getPage(), new String[] { page }));
    }
  
    /**
     * Use this to redirect the browser to the specified page that implements the IExternalPage
     * interface
     */
    public TapestryRedirectException(IRequestCycle cycle, String page, Object 
        parameters)
    {
         this(cycle.getEngine().getService(Tapestry.EXTERNAL_SERVICE).getLink(cycle, 
             cycle.getPage(), getServiceParameters(page, parameters)));
    }
  
    /**
     * Use this to redirect the browser to the specified listenener on the component 
     * that implements the IDirect interface.
     */    
    public TapestryRedirectException(IRequestCycle cycle, IDirect direct, Object 
        parameters)
    {
        this(cycle.getEngine().getService(Tapestry.DIRECT_SERVICE).getLink(cycle, 
          direct, DirectLink.constructServiceParameters(parameters)));
    }

    private static Object[] getServiceParameters(String targetPage, 
        Object parameter)
    {
        Object[] pageParameters = DirectLink.constructServiceParameters(parameter);
        if (pageParameters == null)
        {  
            return new Object[] { targetPage };
        }
        Object[] parameters = new Object[pageParameters.length + 1];
        parameters[0] = targetPage;
        System.arraycopy(pageParameters, 0, parameters, 1, pageParameters.length);
        return parameters;
    }
}

Example (Tapestry4)

import java.util.HashMap;
import java.util.Map;
import org.apache.hivemind.impl.RegistryBuilder;
import org.apache.tapestry.IRequestCycle;
import org.apache.tapestry.RedirectException;
import org.apache.tapestry.engine.IEngineService;
import org.apache.tapestry.engine.ILink;
import org.apache.tapestry.services.ServiceConstants;

public class TapestryRedirectException extends RedirectException {

    public static IEngineService getPageService() {
        return (IEngineService)RegistryBuilder.constructDefaultRegistry()
            .getService("tapestry.services.Page",IEngineService.class);
    }

    public static Map getLinkParams(Strink pageName) {
        Map linkParams=new HashMap();
        linkParams.put(ServiceConstants.PAGE,pageName);
        return linkParams;
    }
       
    private static final long serialVersionUID = 4049918285694842678L;

    public TapestryRedirectException(String url)
    {
        super(url);
    }
   
    public TapestryRedirectException(ILink link)
    {
        this(link.getURL());
    }
   
    /**
     * Use this to redirect the browser to the specified page
     */
    public TapestryRedirectException(IRequestCycle cycle, String page) {
        this(cycle.getEngine().getInfrastructure().getLinkFactory().constructLink(
                TapestryRedirectException.getPageService(),false,
                TapestryRedirectException.getLinkParams(page),false));
    }
  
}
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