Building a Simple REST Service in Java with JetBrains Tools

Introduction

Creating a RESTful web service is a fundamental skill for modern Java developers. In this blog post, we’ll guide you through building a simple REST service using Java and JetBrains‘ powerful toolset. We’ll also provide a Java client code to demonstrate how to call the REST service.

Prerequisites

Before we begin, make sure you have the following prerequisites installed:

• IntelliJ IDEA: Download and install the latest version of IntelliJ IDEA from JetBrains (https://www.jetbrains.com/idea/download/).

Creating the RESTful Web Service

Let’s create a basic RESTful web service that exposes a list of books. Follow these steps:

• Create a New Project:
  • Open IntelliJ IDEA.
  • Define the Data Model:In the „Book.java“ file, define a simple class representing a book:

public class Book {
    private String title;
    private String author;

    public Book(String title, String author) {
        this.title = title;
        this.author = author;
    }

    public String getTitle() {
        return title;
    }

    public String getAuthor() {
        return author;
    }
}

• Click on „Create New Project.“
• Choose „Java“ as the project type.
• Select the appropriate JDK version.
• Create a Java Class:
  • Right-click on the „src“ directory in your project.
  • Choose „New“ > „Java Class.“
  • Name it „Book.“
• Create a RESTful Controller:
  • Right-click on the „src“ directory again.
  • Choose „New“ > „Java Class.“
  • Name it „BookController.“
  In „BookController.java,“ create a simple RESTful controller using the Spring Boot framework:

import org.springframework.web.bind.annotation.GetMapping;
import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.bind.annotation.RestController;

import java.util.Arrays;
import java.util.List;

@RestController
@RequestMapping("/books")
public class BookController {

    @GetMapping
    public List<Book> getAllBooks() {
        return Arrays.asList(
                new Book("Book 1", "Author 1"),
                new Book("Book 2", "Author 2")
        );
    }
}

This code defines a Spring Boot controller that responds to GET requests at the „/books“ endpoint.

Creating a Sample Java Client

Now, let’s create a sample Java client to call the REST service:

1. Create a Java Class for the Client:
   • Right-click on the „src“ directory.
   • Choose „New“ > „Java Class.“
   • Name it „BookClient.“
2. Add Code to Make a GET Request:In „BookClient.java,“ add the following code to make a GET request to the web service:

import org.springframework.web.client.RestTemplate;

public class BookClient {

    public static void main(String[] args) {
        RestTemplate restTemplate = new RestTemplate();
        Book[] books = restTemplate.getForObject("http://localhost:8080/books", Book[].class);

        for (Book book : books) {
            System.out.println("Title: " + book.getTitle());
            System.out.println("Author: " + book.getAuthor());
            System.out.println();
        }
    }
}

This code uses Spring’s RestTemplate to make a GET request to the „/books“ endpoint and displays the retrieved books.

Running the Application

1. Run the web service by executing the main method in the class „BookServiceApplication“ (generated by Spring Boot).
2. Run the client application by executing the main method in „BookClient.java.“You should see the list of books displayed in the client’s console output.

Conclusion

In this blog post, we’ve learned how to create a simple RESTful web service using Java and JetBrains‘ toolset, including IntelliJ IDEA. We’ve also provided a Java client code demonstrating how to call the REST service. With the powerful development tools offered by JetBrains and the versatility of Java, you can build robust web services and applications for various projects.