Skip to site navigation (Press enter)

[CONF] Apache Wicket > AJAX update and file download in one blow

confluence Fri, 27 Jan 2012 06:48:27 -0800

AJAX update and file download in one blow

Page edited by Martin Grigorov

Comment: Add a timeout before making the download. This is needed to let Wicket unlock the used Ajax channel

Changes (2)

Full Content

Following example shows how to use an AJAX request to refresh some components and at the same time make the browser ask back for a file to be downloaded:

	final AJAXDownload download = new AJAXDownload()
	{
		@Override
		protected IResourceStream getResourceStream()
		{
			return createResourceStream(item.getModelObject());
		}
	};
	item.add(download);


	item.add(new AjaxLink<Void>("link") {
		@Override
		public void onClick(AjaxRequestTarget target)
		{
			// do whatever with the target, e.g. refresh components
			target.addComponent(...);

			// finally initiate the download
			download.initiate(target);
		}
	});

We have to add a custom behavior which enables us to initiate the download after the AJAX request has been completed. The overridden hook method provides an IResourceStream (e.g. a FileResourceStream) to serve the actual content.

import org.apache.wicket.ajax.AjaxRequestTarget;
import org.apache.wicket.behavior.AbstractAjaxBehavior;
import org.apache.wicket.request.handler.resource.ResourceStreamRequestHandler;
import org.apache.wicket.util.resource.IResourceStream;

/**
 * @author Sven Meier
 * @author Ernesto Reinaldo Barreiro ([email protected])
 * @author Jordi Deu-Pons ([email protected])
 */
public abstract class AJAXDownload extends AbstractAjaxBehavior
{
        private boolean addAntiCache;

        public AJAXDownload() {
    	    this(true);
    	}
    	
	public AJAXDownload(boolean addAntiCache) {
	    super();
	    this.addAntiCache = addAntiCache;
	}

	/**
	 * Call this method to initiate the download.
	 */
	public void initiate(AjaxRequestTarget target)
	{
		String url = ""

                if (addAntiCache) {
		    url = "" + (url.contains("?") ? "&" : "?");
		    url = "" + "antiCache=" + System.currentTimeMillis();
		}
 
                // the timeout is needed to let Wicket release the channel
                target.appendJavaScript("setTimeout(\"window.location.href=''\", 100);");
	}

	public void onRequest()
	{
		getComponent().getRequestCycle().scheduleRequestHandlerAfterCurrent(
	                new ResourceStreamRequestHandler(getResourceStream(), getFileName()));
	}

	/**
	 * Override this method for a file name which will let the browser prompt with a save/open dialog.
	 * @see ResourceStreamRequestTarget#getFileName()
	 */
	protected String getFileName()
	{
		return null;
	}

	/**
	 * Hook method providing the actual resource stream.
	 */
	protected abstract IResourceStream getResourceStream();
}

Change Notification Preferences

View Online | View Changes | Add Comment