You're reading from Jakarta EE Cookbook Practical recipes for enterprise Java developers to deliver large scale applications with Jakarta EE

Product type Paperback

Published in May 2020

Publisher Packt

ISBN-13 9781838642884

Length 380 pages

Edition 2nd Edition

Languages

Java

Tools

Jakarta EE

Concepts

Application Development

Author (1):

Elder Moraes

View More author details

Running your first MVC 1.0 code

If you have been following Jakarta EE 8 history for a while, you may now be wondering: why is MVC 1.0 here if it was dropped from the Jakarta EE 8 umbrella?

Yes, it is true. MVC 1.0 doesn't belong to the Jakarta EE 8 release. But that doesn'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 Jakarta CDI and JAX-RS to the party.

Getting ready

Add the proper dependencies to your project:

<dependencies>
    <dependency>
        <groupId>jakarta.platform</groupId>
        <artifactId>jakarta.jakartaee-api</artifactId>
        <version>8.0.0</version>
        <scope>provided</scope>
    </dependency>
    <dependency>
        <groupId>javax.mvc</groupId>
        <artifactId>javax.mvc-api</artifactId>
        <version>1.0-pr</version>
    </dependency>  
</dependencies>

How to do it...

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

Start by creating a root for your JAX-RS endpoints:

@ApplicationPath("webresources")
public class AppConfig extends Application{
}

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
}

Now, create a session bean, which will be injected later in your Controller:

@Stateless
public class UserBean {
    
    public User getUser(){
        return new User("Elder", "elder@eldermoraes.com");
    }
}

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";
    }
}

And finally, create 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 Jakarta 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, shown as follows:

@Inject
Models models;

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