Wicketing Javascript through AJAX

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Communication between Java and Javascript cannot be done easier than with Wicket framework, by far the best helper if you’re in Java based web development.

html

<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.1//EN" "http://www.w3.org/TR/xhtml11/DTD/xhtml11.dtd">
<html xmlns:wicket>
<head>
<script type="text/javascript" >
function callWicket() {
	wicketAjaxGet(callback + '&parameter=value', function() {}, function() {});
}
</script>
</head>

<body>
	<div wicket:id = "div"></div>
	<span wicket:id = "wicketAnswer">[]</span>
</body>
</html>

Java – or should I say the magic of Wicket?

package com.somepackage;

import org.apache.wicket.PageParameters;
import org.apache.wicket.ajax.AbstractDefaultAjaxBehavior;
import org.apache.wicket.ajax.AjaxRequestTarget;
import org.apache.wicket.ajax.AjaxSelfUpdatingTimerBehavior;
import org.apache.wicket.markup.html.IHeaderContributor;
import org.apache.wicket.markup.html.IHeaderResponse;
import org.apache.wicket.markup.html.WebMarkupContainer;
import org.apache.wicket.markup.html.WebPage;
import org.apache.wicket.markup.html.basic.Label;
import org.apache.wicket.util.time.Duration;

@SuppressWarnings("serial")
public class BasePage extends WebPage {
	private WebMarkupContainer dummyDiv;
	private Label label;

	public BasePage() {
		this(null);
	}

	public BasePage(final PageParameters parameters) {
		//handle js call to wicket
		final AbstractDefaultAjaxBehavior behavior = new AbstractDefaultAjaxBehavior() {
		    protected void respond(final AjaxRequestTarget target) {
		    	label.setModelObject("Yeah I was just called from Javascript!");
		        target.addComponent(label);
		    }
		};
		add(dummyDiv = new MyWebMarkupContainer("div", behavior));
		//handle wicket call to js
		dummyDiv.add(new AjaxSelfUpdatingTimerBehavior(Duration.seconds(1)) {
			@Override
			protected void onPostProcessTarget(AjaxRequestTarget target) {
				target.appendJavascript("callWicket();");
			}
		});
		dummyDiv.add(behavior);

    	add(label = new Label("wicketAnswer", "Look here to see when wicket is called from javascript"));
    	label.setOutputMarkupId(true);
	}
}

@SuppressWarnings("serial")
class MyWebMarkupContainer extends WebMarkupContainer implements IHeaderContributor {
	AbstractDefaultAjaxBehavior behavior;

	public MyWebMarkupContainer(String id, AbstractDefaultAjaxBehavior behavior) {
		super(id);
		this.behavior = behavior;
	}

	@Override
	public void renderHead(IHeaderResponse response) {
		response.renderJavascript("var callback = '" + behavior.getCallbackUrl() + "';", "insertedjavascript");
	}
}

I don’t think anyone needs explanation about how this works since it’s THAT easy. Only one more thing to add:

Map map = ((WebRequestCycle) RequestCycle.get()).getRequest().getParameterMap();

- this to get the parameters map.

Filed under: Programming by admin

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