| Topics in This Chapter "Life-Cycle Events" on page 274 "Value Change Events" on page 275 "Action Events" on page 281 "Event Listener Tags" on page 290 "Immediate Components" on page 292 "Phase Events" on page 296 "Putting It All Together" on page 305
Web applications often need to respond to user events, such as selecting items from a menu or clicking a button. For example, you might want to respond to the selection of a country in an address form by changing the locale and reloading the current page to better accommodate your users. Typically, you register event handlers with components; for example, you might register a value change listener with a menu in a JSF page like this:
<h:selectOneMenu valueChangeListener="#{form.countryChanged}"...> ... </h:selectOneMenu>
In the preceding code, the method binding #{form.countryChanged} references the countryChanged method of a bean named form. That method is invoked by the JSF implementation after the user makes a selection from the menu. Exactly when that method is invoked is one topic of discussion in this chapter. JSF supports three kinds of events: Value change events Action events Phase events
Value change events are fired by input components such as h:inputText, h:selectOneRadio, and h:selectManyMenu when the component's value changes and the enclosing form is submitted. Action events are fired by command components, for example, h:commandButton and h:commandLink, when the button or link is activated. Phase events are routinely fired by the JSF life cycle. If you want to handle events, you need to have a basic understanding of that life cycle. Let's see how it works. | 