Java EE with annotations overview
The goal of Java™ EE
6 platform development is to minimize the number of artifacts that
you have to create and maintain, thereby simplifying the development
process. Java EE supports the
injection of annotations into your source code, so that you can embed
resources, dependencies, services, and lifecycle notifications in
your source code, without having to maintain these artifacts elsewhere.
An annotation is a modifier or metadata tag that provides additional data to Java classes, interfaces, constructors, methods, fields, parameters, and local variables. Annotations replace boilerplate code, common code that is required by certain applications. For example, an annotation can replace the paired interface and implementation required for a web service. Annotations can also replace additional files that programs require, which are maintained separately. For example, annotations can replace the need for a separately maintained deployment descriptor for enterprise Java beans.
Annotations
- Replace descriptors for most purposes
- Remove the need for marker interfaces (like java.rmi.Remote)
- Allow application settings to be visible in the component they affect
Java EE provides annotations
for the following tasks, among others:
- Developing Enterprise Java bean applications
- Defining and using web services
- Mapping Java technology classes to XML
- Mapping Java technology classes to databases
- Mapping methods to operations
- Specifying external dependencies
- Specifying deployment information, including security attributes
Java EE defines a number
of annotations that can be injected into your source code. To declare
an annotation, you simply precede the keyword with an "at" sign (@).
package com.ibm.counter;
import javax.ejb.Stateless;
@Stateless
public class CounterBean {
}For more information about the categories of annotations that Java EE supports, see Types of annotations.