Book Image

Java EE 8 Cookbook

By : Elder Moraes
Book Image

Java EE 8 Cookbook

By: Elder Moraes

Overview of this book

Java EE is a collection of technologies and APIs to support Enterprise Application development. The choice of what to use and when can be dauntingly complex for any developer. This book will help you master this. Packed with easy to follow recipes, this is your guide to becoming productive with Java EE 8. You will begin by seeing the latest features of Java EE 8, including major Java EE 8 APIs and specifications such as JSF 2.3, and CDI 2.0, and what they mean for you. You will use the new features of Java EE 8 to implement web-based services for your client applications. You will then learn to process the Model and Streaming APIs using JSON-P and JSON-B and will learn to use the Java Lambdas support offered in JSON-P. There are more recipes to fine-tune your RESTful development, and you will learn about the Reactive enhancements offered by the JAX-RS 2.1 specification. Later on, you will learn about the role of multithreading in your enterprise applications and how to integrate them for transaction handling. This is followed by implementing microservices with Java EE and the advancements made by Java EE for cloud computing. The final set of recipes shows you how take advantage of the latest security features and authenticate your enterprise application. At the end of the book, the Appendix shows you how knowledge sharing can change your career and your life.
Table of Contents (14 chapters)

Running your first MVC 1.0 code

If you are following the news about Java EE 8, you may now be wondering: why is MVC 1.0 here if it was dropped from the Java EE 8 umbrella?

Yes, it is true. MVC 1.0 doesn't belong (anymore) to the Java EE 8 release. But it didn't reduce the importance of this great API and I'm sure it will change the way some other APIs work in future releases (for example, JSF).

So why not cover it here? You will use it anyway.

This recipe will show you how to use a Controller (the C) to inject a Model (the M) into the View (the V). It also brings some CDI and JAX-RS to the party.

Getting ready

Add the proper dependencies to your project:

        <dependency>
<groupId>javax</groupId>
<artifactId>javaee-api</artifactId>
<version>8.0</version>
<scope>provided</scope>
</dependency>
<dependency>
<groupId>javax.mvc</groupId>
<artifactId>javax.mvc-api</artifactId>
<version>1.0-pr</version>
</dependency>

How to do it...

  1. Start by creating a root for your JAX-RS endpoints:
@ApplicationPath("webresources")
public class AppConfig extends Application{
}
  1. Create a User class (this will be your MODEL):
public class User {

private String name;
private String email;

public User(String name, String email) {
this.name = name;
this.email = email;
}

//DON'T FORGET THE GETTERS AND SETTERS
//THIS RECIPE WON'T WORK WITHOUT THEM
}
  1. Now, create a Session Bean, which will be injected later in your Controller:
@Stateless
public class UserBean {

public User getUser(){
return new User("Elder", "[email protected]");
}
}
  1. Then, create the Controller:
@Controller
@Path("userController")
public class UserController {

@Inject
Models models;

@Inject
UserBean userBean;

@GET
public String user(){
models.put("user", userBean.getUser());
return "/user.jsp";
}
}
  1. And finally, the web page (the View):
<head>
<meta http-equiv="Content-Type" content="text/html;
charset=UTF-8">
<title>User MVC</title>
</head>
<body>
<h1>${user.name}/${user.email}</h1>
</body>

Run it on a Java EE 8 server and access this URL:

http://localhost:8080/ch01-mvc/webresources/userController

How it works...

The main actor in this whole scenario is the Models class injected into the Controller:

@Inject
Models models;

It's a class from MVC 1.0 API that owns the responsibility, in this recipe, of letting the User object be available for the View layer. It's injected (using CDI) and uses another injected bean, userBean, to do it:

models.put("user", userBean.getUser());

So, the View can easily access the values from the User object using expression language:

<h1>${user.name}/${user.email}</h1>

See also

  • You can stay tuned with everything related to MVC specification at https://github.com/mvc-spec
  • The source code of this recipe is at https://github.com/eldermoraes/javaee8-cookbook/tree/master/chapter01/ch01-mvc