Book Image

Developing Middleware in Java EE 8

Book Image

Developing Middleware in Java EE 8

Overview of this book

Middleware is the infrastructure in software based applications that enables businesses to solve problems, operate more efficiently, and make money. As the use of middleware extends beyond a single application, the importance of having it written by experts increases substantially. This book will help you become an expert in developing middleware for a variety of applications. The book starts off by exploring the latest Java EE 8 APIs with newer features and managing dependencies with CDI 2.0. You will learn to implement object-to-relational mapping using JPA 2.1 and validate data using bean validation. You will also work with different types of EJB to develop business logic, and with design RESTful APIs by utilizing different HTTP methods and activating JAX-RS features in enterprise applications. You will learn to secure your middleware with Java Security 1.0 and implement various authentication techniques, such as OAuth authentication. In the concluding chapters, you will use various test technologies, such as JUnit and Mockito, to test applications, and Docker to deploy your enterprise applications. By the end of the book, you will be proficient in developing robust, effective, and distributed middleware for your business.
Table of Contents (18 chapters)
Title Page
Copyright and Credits
Dedication
Packt Upsell
Contributors
Preface
Index

Criteria queries


Criteria queries are queries that can be built by instantiating Java objects, rather than specifying a string syntax. The advantage of this is that you can avoid query syntax errors; as the correctness of your queries will be guaranteed by the compiler, you can then detect syntax errors early.

The criteria query API may appear complex at first sight, but later you will get used to its syntax and use it without any hassle. Now, let's start examining a simple example to create a query equivalent to SELECT x FROM Movie x using the criteria API:

CriteriaBuilder cb = entityManager.getCriteriaBuilder(); //01
CriteriaQuery<Movie> q = cb.createQuery(Movie.class); //02
Root<Movie> root = q.from(Movie.class); //03
q.select(root); //04
List<Movie> movies = entityManager.createQuery(q).getResultList(); //05

Let's look though the previous example:

  • In line 01, we have instantiated a criteria builder object; the criteria builder, as the name suggests, is an object that we...