JSF Annotations

Remarks#

I get many informations from this web sites:

Introduction to annotations

Why annotations?

Generally we use annotation to facilitate the development and to make the code more clear and clean.

What are annotations?

Java 5 annotations provide standardization of metadata in a general goal. This metadata associated with Java features can be exploited in the compilation or execution.

Java was modified to allow the implementation of annotations:

A dedicated syntax was added in Java to allow the definition and use of annotations.
bytecode is enhanced to allow storage of annotations.

Where can annotations be used?

Annotations can be used with :

packages, classes, interfaces, constructors, methods, fields, parameters, variables or annotations themselves.

Categories of annotation

There are three categories of annotation:

Markers: These annotations do not have an attribute

For example @Deprecated, @Override …

Single value annotation: these annotations have only one attribute

For example @MyAnnotation ( "test")

Full annotations: these annotations have multiple attributes

For example @MyAnnotation (arg1 = "test 3", arg2 = "test 2", arg3 = "test3")

Like we see before you can create your own annotation

Managed bean scope annotation

Create managed bean

To create a manage bean you need the annotation @ManagedBean

for example:

@ManagedBean
public class Example {}

You need the package:

import javax.faces.bean.ManagedBean;

Managed bean Scope

We use annotations to define the scope in which the bean will be stored.

There are many scope of managed bean: @NoneScoped, @RequestScoped, @ViewScoped, @SessionScoped, @ApplicationScoped, …

Application (@ApplicationScoped): Application scope persists across all users’ interactions with a web application.
Session (@SessionScoped): Session scope persists across multiple HTTP requests in a web application.
View (@ViewScoped): View scope persists during a user’s interaction with a single page (view) of a web application.
Request (@RequestScoped): Request scope persists during a single HTTP request in a web application.
None (@NoneScoped): Indicates a scope is not defined for the application.
Custom (@CustomScoped): A user-defined, nonstandard scope. Its value must be configured as a java.util.Map. Custom scopes are used infrequently.