The Java EE 5 Tutorial (PDF) - Oracle Software Downloads

Configuring Beans
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Referencing a Java Enum Type
As of version 1.2 of JavaServer Faces technology, a managed bean property can also be a Java
Enum type (see http://java.sun.com/javase/6/docs/api/java/lang/Enum.html). In this
case, the value element of the managed-property element must be a String that matches one
of the String constants of the Enum. In other words, the String must be one of the valid values
that can be returned if you were to call valueOf(Class, String) on enum, where Class is the
Enum class and String is the contents of the value subelement. For example, suppose the
managed bean property is the following:
public enum Suit { Hearts, Spades, Diamonds, Clubs}
...
public Suit getSuit() { ... return Suit.Hearts; }
Assuming that you want to configure this property in the application configuration file, the
corresponding managed-property element would look like this:
Suit
Hearts
When the system encounters this property, it iterates over each of the members of the enum and
calls toString() on each member until it finds one that is exactly equal to the value from the
value element.
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:
customer
CustomerBean
The Java EE 5Tutorial • June 2010