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A First Look at the Wicket Framework

To be able to manipulate the user-entered values, the onSubmit() method of the wicket.markup.html.form.Form method must be overwritten. The onSubmit() method of the PizzaForm class follows:

 

  protected void onSubmit()
  {
    PizzaModel pizzaModel = (PizzaModel) getModelObject();

    setResponsePage(new WicketTestConfPage(pizzaModel));
  }

Of interest here are the getModelObject() and requestCycle.setResponsePage() methods.

The getModelObject() method call obtains an instance of the Model object populated with the user-entered values. The requestCycle.setResponsePage() directs the browser to a new page. The WebPage instance that the browser will be redirected to must have a constructor taking an instance of the Model object as a parameter.

Here is the source for the confirmation page:


public class WicketTestConfPage extends WebPage
{

  public WicketTestConfPage(PizzaModel pizzaModel)
  {
    super();
    add(new Label("crust", pizzaModel.getCrust()));
    add(new Label("pepperoni", new Boolean(pizzaModel.getPepperoni())
        .toString()));
    add(new Label("sausage", new Boolean(pizzaModel.getSausage()).toString()));
    add(new Label("onions", new Boolean(pizzaModel.getOnions()).toString()));
    add(new Label("greenPeppers", new Boolean(pizzaModel.getGreenPeppers())
        .toString()));
    add(new Label("comments", pizzaModel.getComments()));
  }
}

All it does is create some labels to displaying the values of the Model object it takes as its sole constructor parameter.

Here are the relevant sections of the corresponding HTML file:

<table
    style="text-align: left; width: 427px; height: 112px;" border="1"


        cellpadding="0" cellspacing="0">


        <tbody>


            <tr>


                <td
    style="font-weight: bold; text-align: right;">Crust:</td>


              
     <td><span
    wicket:id="crust">Hello</span></td>


            </tr>


            <tr>


                <td
    style="font-weight: bold; text-align: right;">Toppings:</td>


              
     <td>Pepperoni:&nbsp; <span
    wicket:id="pepperoni"></span>


              
     Sausage:&nbsp;<span
    wicket:id="sausage"></span>&nbsp;Onions: &nbsp;<span


                  
     wicket:id="onions"></span>&nbsp;Green
    Peppers:&nbsp;<span


                  
     wicket:id="greenPeppers"></span></td>


            </tr>


            <tr>


                <td
    style="font-weight: bold; text-align: right;">Comments:</td>


              
     <td><span
    wicket:id="comments"></span></td>


            </tr>


        </tbody>


    </table>

Of interest here are the <span> fields, these correspond to the labels in the WicketTestConfPage java class. You may notice some of the <span> tags have text inside them, this text will only be displayed in the browser when mocking up the pages, when displayed from the Wicket application, they will display whatever value the corresponding Label instances have.

After entering some arbitrary data and submitting the form, here is how the confirmation page looks:
Pizza builder confirmation page.

Conclusions

Wicket provides the following advantages over other web application frameworks:

Provides clear separation of concerns where web designers don't have to add any special markup to the HTML files to make them work with wicket, allowing them to use any WYSIWYG editor to create the pages.
Makes it easy to create Java code that is able to execute outside of a servlet container or application server, making this code easy to unit test. For these reasons, Wicket is a good choice when creating web applications and dynamic web sites.
Does not require special XML configuration files.

Some disadvantages of Wicket:

Not as well documented as other web application frameworks like Struts or JavaServer Faces.
Has limited AJAX support (in the latest beta), although more AJAX support is planned.

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