Book Image

Java EE 8 Application Development

Book Image

Java EE 8 Application Development

Overview of this book

Java EE is an Enterprise Java standard. Applications written to comply with the Java EE specification do not tie developers to a specific vendor; instead they can be deployed to any Java EE compliant application server. With this book, you’ll get all the tools and techniques you need to build robust and scalable applications in Java EE 8. This book covers all the major Java EE 8 APIs including JSF 2.3, Enterprise JavaBeans (EJB) 3.2, Contexts and Dependency Injection (CDI) 2.0, the Java API for WebSockets, JAX-RS 2.1, Servlet 4.0, and more. The book begins by introducing you to Java EE 8 application development and goes on to cover all the major Java EE 8 APIs. It goes beyond the basics to develop Java EE applications that can be deployed to any Java EE 8 compliant application server. It also introduces advanced topics such as JSON-P and JSON-B, the Java APIs for JSON processing, and the Java API for JSON binding. These topics dive deep, explaining how the two APIs (the Model API and the Streaming API) are used to process JSON data. Moving on, we cover additional Java EE APIs, such as the Java API for Websocket and the Java Message Service (JMS), which allows loosely coupled, asynchronous communication. Further on, you’ll discover ways to secure Java EE applications by taking advantage of the new Java EE Security API. Finally, you’ll learn more about the RESTful web service development using the latest JAX-RS 2.1 specification. You’ll also get to know techniques to develop cloud-ready microservices in Java EE.
Table of Contents (21 chapters)
Title Page
Credits
About the Author
About the Reviewers
www.PacktPub.com
Customer Feedback
Preface

Persisting application data across requests


In the previous section, we saw how it is possible to store an object in the request by invoking the HttpRequest.setAttribute() method and how later this object can be retrieved by invoking the HttpRequest.getAttribute() method. This approach only works if the request was forwarded to the servlet invoking the getAttribute() method. If this is not the case, the getAttribute() method will return null.

It is possible to persist an object across requests. In addition to attaching an object to the request object, an object can also be attached to the session object or to the servlet context. The difference between these two is that objects attached to the session will not be visible to different users, whereas objects attached to the servlet context are.

Attaching objects to the session and servlet context is very similar to attaching objects to the request. To attach an object to the session, the HttpServletRequest.getSession() method must be invoked...