The Java EE 5 Tutorial

Referencing an Initialization Parameter

Another powerful feature of the managed bean creation facility is the ability to reference implicit objects from a managed bean property.

Suppose that you have a page that accepts data from a customer, including the customer’s address. Suppose also that most of your customers live in a particular area code. You can make the area code component render this area code by saving it in an implicit object and referencing it when the page is rendered.

You can save the area code as an initial default value in the context initParam implicit object by adding a context parameter to your web application and setting its value in the deployment descriptor. For example, to set a context parameter called defaultAreaCode to 650, add a context-param element to the deployment descriptor, give the parameter the name defaultAreaCode and the value 650.

Next, you write a managed-bean declaration that configures a property that references the parameter:


To access the area code at the time the page is rendered, refer to the property from the area component tag’s value attribute:

<h:inputText id=area value="#{customer.areaCode}"

Retrieving values from other implicit objects is done in a similar way. See Implicit Objects for a list of implicit objects.