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

Configuring Beans
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a. Start typing the name of the class you are looking for in the Class Name field. While you
are typing, the dialog will show the matching classes.
b. Select the class from the Matching Classes box.
c. Click OK.
8. In the Add Managed Bean dialog:
a. Select the bean’s scope from the Scope menu.
b. Click Add.
9. In the Projects tab, right-click the bookstore1 project, and select Undeploy and Deploy.
The preceding steps will add the managed-bean element and three elements inside of it: a
managed-bean-name element, a managed-bean-class element and a managed-bean-scope
element. You will need to edit the XML of the configuration file directly to further configure this
managed bean.
The managed-bean-name element defines the key under which the bean will be stored in a scope.
For a component’s value to map to this bean, the component tag’s value attribute must match
the managed-bean-name up to the first period. For example, this value expression maps to the
shape property of the ImageArea instance, NA:
value="#{NA.shape}"
The part before the period (.) matches the managed-bean-name of ImageArea. “Adding UI
Components to a Page Using the HTML Component Tags” on page 325 has more examples of
using the value attribute to bind components to bean properties.
The managed-bean-class element defines the fully qualified name of the JavaBeans component
class used to instantiate the bean. It is the application developer’s responsibility to ensure that
the class complies with the configuration of the bean in the application configuration resource
file. This includes making sure that the types of the properties in the bean match those
configured for the bean in the configuration file.
The managed-bean-scope element defines the scope in which the bean will be stored. The four
acceptable scopes are none, request, session,orapplication. If you define the bean with a
none scope, the bean is instantiated anew each time it is referenced, and so it does not get saved
in any scope. One reason to use a scope of none is that a managed bean references another
managed bean. The second bean should be in none scope if it is supposed to be created only
when it is referenced. See “Initializing Managed Bean Properties” on page 443 for an example of
initializing a managed bean property.
If you are configuring a backing bean that is referenced by a component tag’s binding attribute,
you should define the bean with a request scope. If you placed the bean in session or application
scope instead, the bean would need to take precautions to ensure thread safety because
UIComponent instances depend on running inside of a single thread.
The Java EE 5Tutorial • June 2010