Sometimes it is good to be stateless. As the core of Wicket is focused on managing statefull behavior there is sometimes a lack of support for stateless pages. The goal of this package is to add a few components that provide more comprehensive stateless features for Wicket.
These components currently include a StatelessLink and a StatelessAjaxFallbackLink. Please let me know if you need more components.
This example is based on the Wicket Link example. The full source code for this very simple example is available at http://jolira-tools.googlecode.com/svn/wicket-stateless/trunk/demo/src/main/java/com/jolira/stateless/.
`` public class WicketApplication extends WebApplication { @Override public Class getHomePage() { return HomePage.class; }
@Override
protected IRequestCycleProcessor newRequestCycleProcessor() {
return new StatelessWebRequestCycleProcessor();
}
} ``
== HomePage.html ==
<html
xmlns:wicket="http://wicket.apache.org/dtds.data/wicket-xhtml1.4-strict.dtd">
<head>
<title>Stateless Wicket</title>
<style type="text/css">
span.wicket-ajax-indicator {
margin: 0;
padding: 0;
padding-left: 2px;
}
</style>
</head>
<body>
counter 2:
<span wicket:id="c2"></span>
<a href="#" wicket:id="c2-link">increment</a>
( statless ajax fallback link. this link uses ajax when it is available,
and a regular wicket roundtrip when ajax or javascript are not available
and the page should be stateless. )
<br />
<form wicket:id="inputForm" method="get">
<label for="a">a:</label>
<input wicket:id="a" id="a" type="text" size="15"/><br/>
<label for="b">b:</label>
<input wicket:id="b" id="b" type="text" size="15"/><br/>
<input type="submit" value="Execute" />
</form>
<select wicket:id="c" />
</body>
</html>== HomePage.java ==
public class HomePage extends WebPage {
private static final String COUNTER_PARAM = "counter";
public HomePage(final PageParameters parameters) {
final String _counter = getParameter(parameters, COUNTER_PARAM);
final int counter = _counter != null ? Integer.parseInt(_counter) : 0;
final Label c2 = new Label("c2", Integer.toString(counter));
final PageParameters updated = updateParams(counter);
final Link<?> c2Link = new StatelessAjaxFallbackLink<Void>("c2-link",
null, updated) {
private static final long serialVersionUID = 1L;
@Override
public void onClick(final AjaxRequestTarget target) {
if (target != null) {
target.addComponent(c2);
}
}
};
c2.setMarkupId(c2.getId()); // Required to make stateless Ajax work
c2.setOutputMarkupId(true);
add(c2Link);
add(c2);
final String _a = getParameter(parameters, "a");
final String _b = getParameter(parameters, "b");
final Form<String> form = new StatelessForm<String>("inputForm") {
private static final long serialVersionUID = -1804691502079814185L;
@Override
protected void onSubmit() {
info("clicked sumbit");
}
};
final TextField<String> a = new TextField<String>("a",
new Model<String>(_a));
final TextField<String> b = new TextField<String>("b",
new Model<String>(_b));
final DropDownChoice<String> c = new DropDownChoice<String>("c",
new Model<String>("2"), Arrays.asList(new String[] { "1", "2",
"3" }));
c.add(new StatelessAjaxFormComponentUpdatingBehavior("onchange") {
private static final long serialVersionUID = 3837958099817895568L;
@Override
protected PageParameters getPageParameters() {
return new PageParameters();
}
@Override
protected void onUpdate(final AjaxRequestTarget target) {
final String value = c.getModelObject();
System.out.println("xxxxxxxxxxxxxxxxxx: " + value);
setResponsePage(HomePage.class);
}
});
c.setMarkupId("c");
form.add(a);
form.add(b);
add(form);
add(c);
}
private String getParameter(final PageParameters parameters,
final String key) {
final String[] value = (String[]) parameters.get(key);
if (value == null || value.length < 1) {
return null;
}
return value[0];
}
protected final PageParameters updateParams(final int counter) {
final PageParameters updatedParameters = new PageParameters();
updatedParameters.put(COUNTER_PARAM, Integer.toString(counter + 1));
return updatedParameters;
}
}== Maven ==
This component is available in [http://repo2.maven.org/maven2/com/jolira/ Maven Central]. Simply add the following lines of configuration to our pom.xml:
<dependencies>
<dependency>
<groupId>com.jolira</groupId>
<artifactId>wicket-stateless</artifactId>
<version>1.0.8</version>
</dependency>
</dependencies>== Consider Using [http://code.google.com/p/jolira-tools/wiki/guicier gucier] ==
Working with stateless pages creates the need for passing state in different ways. Application such as http://mobile.walmart.com pass this state using [http://www.wicketframework.org/apidocs/wicket/PageParameters.html PageParameters].
In order to simplify your code you may want to consider using [http://code.google.com/p/jolira-tools/wiki/guicier gucier], which allows users to pass [http://www.wicketframework.org/apidocs/wicket/PageParameters.html PageParameters] in a type-safe manner (and additionally supports [http://code.google.com/p/google-guice/wiki/Injections Guice constructor injection]).