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

Creating CDI services


In creating the services that interact with JPA, we decided to abstract some methods out into a parent service that all our services can inherit. It wasn't necessary to develop it in this way, as it is all down to personal preference in the end.

  1. Our parent service will inject an EntityManager for JPA calls, and will take advantage of Java Generics to provide some common methods for retrieving an entity by an identifier and retrieving all instances of an entity type:

    public abstract class AbstractService<T> {
    
      @Inject
    
      @BookDB
      private EntityManager entityManager;
      private Class<T> entityClass;
      public AbstractService() {}
      public AbstractService(Class<T> entityClass) {
        this.entityClass = entityClass;
      }
      protected EntityManager getEntityManager() {
        return entityManager;
      }
    
      @Transactional
      public T get(Long id) throws ServiceException {
        ...
      }
    
      @Transactional
      public List<T> getAll(Map<String, String> parameters...