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

Dependent beans for producers


In creating a new bean with a producer, there may be situations in which we do not want an existing instance of a bean to be injected into our producer, but would prefer an instance that is dependent on the scope of the bean that produced it.

Taking our example from the previous section, we can resolve the problem of a requestscoped bean being promoted to the session scope with the following producer:

@Produces
@Preferred
@SessionScoped
public BookSearch getSearch
(@New FictionSearch fs, @New NonFictionSearch nfs) {

  switch (searchType) {
    case FICTION:
      fs.setDescription("Hello from Fiction Search!");
      return fs;
    case NONFICTION:
      return nfs;
    default:
      return null;
  }
}

Deploying our example and accessing http://localhost:8080/chapter5/index.jsf, we see the same initial screen as shown previously. If we now refresh the page or click on Next Request, we see that the session-scoped bean has been retained as we originally intended...