First
of all backing beans are not entirely different from managed beans. Very
unpopular thing to say, but it’s true. Backing Bean is also a managed bean with
some specific settings.
What is a managed bean?
Managed
beans are Java classes that you register
with the application using various configuration files. When the JSF
application starts up, it parses these
configuration files and the beans are made available and can be referenced
in an EL expression, allowing access
to the beans' properties and methods.
Whenever a managed bean is referenced for the first time and it does not
already exist, the Managed Bean Creation Facility instantiates the bean by
calling the default constructor method on the bean. If any properties are also
declared, they are populated with the declared default values.
What is a Backing Bean?
Backing
beans are managed beans that contain logic and properties for UI components on a JSF page.
The
key point here is: It has a one-to-one relationship with a single
JSF page.
It exposes
setter and getter methods for the components contained on the page.
When
you create your JSF page, if you choose
to automatically expose UI components by selecting one of the choices in
the Page Implementation option of the Create JSF Page dialog, JDeveloper automatically creates a backing bean
(or uses a managed bean of your choice) for the page.
For each component you add to the page, JDeveloper
then inserts a bean property for
that component, and uses the binding attribute to bind component instances to
those properties, allowing the bean to accept and return component instances.
Let’s
see how to create a backing bean and what Happens when we create one.
·
Create
a new Jspx page, Expand “Page Implementation” and click on “Automatically
Expose UI Components……..”
·
See
the structure of the blank page created. Notice the components present.
·
You
can find properties present in the bean for these components.
·
Then
drag adf components like panel box and input button to the page.
·
You
can see that JDeveloper created two properties for the above created
components.
