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| |
| <body> |
| Provides renderable HTML controls. Controls implement the |
| {@link org.apache.click.Control} interface to perform server side request |
| processing. At the top level a Pages controls are processed by the |
| ClickServlet. Some controls can contain child controls which they will inturn |
| process. These container controls include Form, FieldSet, Panel and Table. |
| <p/> |
| Using these controls are similar to traditional Swing GUI programming. While these |
| controls do not provide a full Swing style MVC implementation, they provide a |
| simplified programming model and high performance. |
| |
| <h3>Action Listeners</h3> |
| |
| Controls extending {@link org.apache.click.control.AbstractControl} can use an action |
| listener event callback mechanism similar the <tt>java.awt.ActionListener</tt> callback. |
| <p/> |
| Click supports two styles of action listeners, the first is using the |
| {@link org.apache.click.ActionListener} interface which provides compile time safety. |
| The second is to register the action listener via the <tt>setListener(Object, String)</tt> |
| method where you specify the call back method via its name. This second style uses |
| less lines of code, but has no compile time safety. |
| <p/> |
| Examples of these two action listener styles are provided below: |
| |
| <pre class="prettyprint"> |
| public class ActionDemo extends Page { |
| |
| // Uses listener style 1 |
| @Bindable public ActionLink link = new ActionLink(); |
| |
| // Uses listener style 2 |
| @Bindable public ActionButton button = new ActionButton(); |
| |
| public ActionDemo() { |
| |
| // Verbose but provides compile time safety |
| link.setActionListener(new ActionListener() { |
| public boolean onAction(Control source) { |
| return onLinkClick(source); |
| } |
| }); |
| |
| // Succinct but typos will cause runtime errors |
| button.setListener(this, "onButtonClick"); |
| } |
| |
| // Event Handlers --------------------------------------------------------- |
| |
| public boolean onLinkClick(Control source) { |
| .. |
| return true; |
| } |
| |
| public boolean onButtonClick() { |
| .. |
| return true; |
| } |
| } </pre> |
| |
| All call back listener methods must return a boolean value. If they return true |
| the further processing of other controls and page methods should continue. |
| Otherwise if they return false, then any further processing should be aborted. |
| By returning false you can effectively exit at this point and redirect or forward |
| to another page. |
| |
| </body> |
