HTML and CSS Reference
In-Depth Information
private String contract = "basic";
public String getContract() {
return contract;
}
public void setContract(String contract) {
this.contract = contract;
}
}
Listing 5-16 could be extended to pick the selected contract from a cookie or from the database so that the user
would not have to select the contract to apply every time he uses the application.
The method to use for mapping contracts to views depends on your application requirements. You can mix the
two methods to achieve maximum flexibility.
Faces Flows
Since the introduction of JavaServer Faces, a consistent complaint by developers has been the lack of support for a
scope that covers a user flow such as a wizard and multistep sign-up form. In JSF 2.0 the
@ViewScope
annotation was
introduced to support variable persistence while staying in the same view.
@ConversationScoped
was introduced
for CDI (Component Dependency Injection) beans in JSF 2.0, and by injecting the
javax.enterprise.context.
Conversation
interface into a managed bean it was possible to start and end long-running conversations. With
@ViewScope and @ConversationScoped scopes, you can implement multistep sign-up forms and wizards, but once
implemented you find that the final product is rather disintegrated and not easy to reuse. Faces flows deals with these
shortcomings by providing a fully integrated solution where you can specify multiple user flows in a flow definition
supported by managed beans annotated with @FlowScoped and with the ability to package flows in separate
directories and JAR. Flows can also interact using inbound and outbound parameters.
■
@FlowScoped
is a CDI scope and you must therefore enable CDI in your application by including
beans.xml
in the
WEB-INF/
directory or in the
META-INF/
directory if the flow is packaged in Jar.
Note
Flow definitions
You can define flows either in XML files (residing with the other flow files suffixed
-flow.xml
) or in a class annotated
with
@FlowDefinition
. In classes annotated with
@FlowDefinition
you specify the flow using the
FlowBuilder
API,
whereas the XML file defines the flow using the
http://xmlns.jcp.org/jsf/flow
XML namespace and schema.
The benefit of using the
FlowBuilder
is that you have full programmatic control of how the flow is defined. That is,
you can build your flows based on runtime information. The disadvantage is that it is much more difficult to quickly
get overview of the flow simply by looking at the code, unlike the XML version. Listing 5-17 shows a flow definition
expressed in XML.
