Book Image

JBoss Weld CDI for Java Platform

By : Kenneth Finnigan
Book Image

JBoss Weld CDI for Java Platform

By: Kenneth Finnigan

Overview of this book

CDI simplifies dependency injection for modern application developers by taking advantage of Java annotations and moving away from complex XML, while at the same time providing an extensible and powerful programming model. "JBoss Weld CDI for Java Platform" is a practical guide to CDI's dependency injection concepts using clear and easy-to-follow examples. This will help you take advantage of the power behind CDI, as well as providing a firm understanding of how to use it within your applications. "JBoss Weld CDI for Java Platform" covers all the major aspects of CDI, breaking it down into understandable pieces. This book will take you through many examples of how these concepts can be utilized, helping you get up and running quickly and painlessly. "JBoss Weld CDI for Java Platform" gives you an insight into the different scopes provided by CDI and the use cases for which each has been designed. You will learn everything about dependency injection, scopes, events, producers, and more from JBoss Weld CDI, as well as how producers can create new beans for consumption within your application. You will also learn how to build a real world application with CDI using JSF and AngularJS for different web interfaces.
Table of Contents (17 chapters)
JBoss Weld CDI for Java Platform
Credits
About the Author
About the Reviewer
www.PacktPub.com
Preface
Index

Chapter 6. Interceptors and Decorators

This chapter will cover how interceptors and decorators can be utilized within our CDI applications, while doing so in a typesafe manner through annotations. We will examine how interceptor bindings are created through annotations and then how to create and enable an interceptor. In decorators, we talk about what a delegate is before enabling decorators in a manner similar to interceptors.

Interceptors and decorators behave as two different sides of the same coin. Interceptors are perfect for separating concerns that are orthogonal to our application purpose by cutting across all layers of our application to perform an identical task. These tasks usually relate to technical matters such as transaction management, security, and method logging.

As interceptors are not aware of the semantics of what they intercept, they are not suited for separating business concerns, but that's where decorators come into play. As decorators intercept methods on a specific...