RESTful Web Services – First Application

RESTful web services allow us to create web applications that are stateless, scalable, and easy to maintain. In this article, we will create our first RESTful web service using Java and the Spring Framework.

Prerequisites

To follow along with this tutorial, you’ll need to meet the following prerequisites:

• Java 8 or higher
• Spring Tool Suite or Eclipse ID
• Maven installed on your system

Getting Started

First, let us create a new Maven project in Spring Tool Suite or Eclipse ID. Select the “New” option and choose “Maven project.” Fill out the necessary details, such as the Group Id, Artifact Id, and Version. Choose a name for your project, and click “Finish.”

Once your project is set up, you can add a dependency on Spring Boot Starter Web. This dependency will provide us with all the necessary libraries to build a RESTful web service.

<dependency>
    <groupId>org.springframework.boot</groupId>
    <artifactId>spring-boot-starter-web</artifactId>
</dependency>

Creating the RESTful Resource

After setting up the project, we can create a RESTful resource. Accomplishing this requires the use of the @RestController and @RequestMapping annotations. These two annotations help to identify the Java class as a RESTful endpoint, and it allows us to specify the HTTP requests that should be sent to this endpoint.

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

@RestController
public class HelloWorldController {
  @RequestMapping(value = "/", method = RequestMethod.GET)
  public String helloWorld() {
    return "Hello, World!";
  }
}

The @RestController annotation identifies the class as a RESTful endpoint. The @RequestMapping annotation specifies the HTTP request, which in this case is a GET request to "/".

Running the Application

Now that we have created the RESTful resource, we can run the application. Open up the command prompt or terminal, and navigate to the directory where the project is located. Type in the following command:

mvn spring-boot:run

After the command has been executed, the application will start running. Open up a browser and type in http://localhost:8080. A page with the text Hello, World! should appear on your screen.

Conclusion

In this article, we covered the basics of creating a RESTful web service using the Spring Framework. We learned about the necessary prerequisites, how to create a new Maven project, and how to create a RESTful resource using the @RestController and @RequestMapping annotations. Finally, we learned how to run the application and view the response in a web browser.