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

What is a servlet?


A servlet is a Java class used to extend the capabilities of servers that host server-side web applications. Servlets can respond to requests and generate responses. The base class for all servlets is javax.servlet.GenericServlet, defines a generic, protocol-independent servlet.

By far the most common type of servlet is an HTTP servlet. This type of servlet is used for handling HTTP requests and generating HTTP responses. An HTTP servlet is a class that extends the javax.servlet.http.HttpServlet class, which is a subclass of javax.servlet.GenericServlet.

A servlet must implement one or more methods to respond to specific HTTP requests. These methods are overridden from the parentHttpServlet class. As can be seen in the following table, these methods are named in such a way that knowing which one to use is intuitive:

HTTP request

HttpServlet method

GET

doGet(HttpServletRequest request, HttpServletResponse response)

POST

doPost(HttpServletRequest request, HttpServletResponse response...