Book Image

Jakarta EE Cookbook - Second Edition

By : Elder Moraes
Book Image

Jakarta EE Cookbook - Second Edition

By: Elder Moraes

Overview of this book

Jakarta EE is widely used around the world for developing enterprise applications for a variety of domains. With this book, Java professionals will be able to enhance their skills to deliver powerful enterprise solutions using practical recipes. This second edition of the Jakarta EE Cookbook takes you through the improvements introduced in its latest version and helps you get hands-on with its significant APIs and features used for server-side development. You'll use Jakarta EE for creating RESTful web services and web applications with the JAX-RS, JSON-P, and JSON-B APIs and learn how you can improve the security of your enterprise solutions. Not only will you learn how to use the most important servers on the market, but you'll also learn to make the best of what they have to offer for your project. From an architectural point of view, this Jakarta book covers microservices, cloud computing, and containers. It allows you to explore all the tools for building reactive applications using Jakarta EE and core Java features such as lambdas. Finally, you'll discover how professionals can improve their projects by engaging with and contributing to the community. By the end of this book, you'll have become proficient in developing and deploying enterprise applications using Jakarta EE.
Table of Contents (14 chapters)

Running your first JSON-B 1.0 code

Jakarta JSON Binding is an API for converting Java objects into/from JSON messages in a standardized way. It defines a default mapping algorithm to convert Java classes into JSON and still lets you customize your own algorithms.

With JSON-B (JSON-Binding), Jakarta EE has a complete set of tools to work with JSON, such as the JSON API and JSON-P (JSON-Padding). No third-party frameworks are needed anymore (although you are still free to use them).

This quick recipe will show you how to use JSON-B to convert a Java object into and from a JSON message.

Getting ready

Let's add our dependencies to the project:

<dependencies>
<dependency>
<groupId>org.eclipse</groupId>
<artifactId>yasson</artifactId>
<version>1.0.3</version>
</dependency>
<dependency>
<groupId>org.glassfish</groupId>
<artifactId>javax.json</artifactId>
<version>1.1.4</version>
</dependency>
</dependencies>

How to do it...

You need to perform the following steps to try this recipe:

  1. Let's create a User class as a model for our JSON message:
public class User {

private String name;
private String email;

public User(){
}

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

@Override
public String toString() {
return "User{" + "name=" + name + ", email=" + email + '}';
}

//DON'T FORGET THE GETTERS AND SETTERS
//THIS RECIPE WON'T WORK WITHOUT THEM

}
  1. Then, let's create a class to use JSON-B to transform an object:
public class JsonBUser {

public static void main(String[] args) throws Exception {
User user = new User("Elder", "[email protected]");

Jsonb jb = JsonbBuilder.create();
String jsonUser = jb.toJson(user);
User u = jb.fromJson(jsonUser, User.class);

jb.close();
System.out.println("json: " + jsonUser);
System.out.println("user: " + u);

}
}
  1. The result printed is as follows:
 json: {"email":"[email protected]","name":"Elder"}
user: User{name=Elder, [email protected]}

The first line is the object transformed into a JSON string. The second is the same string converted into an object.

How it works...

It uses the getters and setters defined in the User class to transform both ways and that's why they are so important.

See also

  • You can stay tuned with everything related to JSON-B at http://json-b.net/.
  • The source code of this recipe is at https://github.com/eldermoraes/javaee8-cookbook/tree/master/chapter01/ch01-jsonb.