How to Make a Simple RestController in Spring Boot?

In Spring Boot, a RestController is used to create RESTful web services that return JSON or XML responses. It combines the functionality of @Controller and @ResponseBody, making it easy to handle HTTP requests and send responses without writing boilerplate code.

• @RestController eliminates the need to annotate each method with @ResponseBody.
• It is ideal for building APIs for web or mobile applications.

Steps to Create a Simple RestController in Spring Boot

Step 1: Create a New Spring Boot Maven Project

• Open IntelliJ IDEA.
• Click on New Project.
• Select Spring Initializr and click Next.
• Enter the project details:
• Group Id: com.geeksforgeeks
• Artifact Id: springboot-restcontroller
• Project Type: Maven
• Packaging: jar
• Java Version: 17
• Click Next.
• Select the required dependency:
• Spring Web
• Click Finish to create the project.

After completing these steps, IntelliJ IDEA will generate a Spring Boot Maven project with all required configurations.

Step 2: Project Structure

Step 3: Add pom.xml

Here is the pom.xml for your project:

Step 4: Create SpringBootApplication Class

Create SpringBootApplication.java inside src/main/java/com/geeksforgeeks/SpringBootApplication/:

Step 5: Create a Simple RestController

Create Controller.java inside src/main/java/com/geeksforgeeks/SpringBootApplication/controller/:

Explanation:

• @RestController -> Marks this class as a RESTful controller.
• @RequestMapping("/api") -> Sets the base URL for all endpoints.
• @GetMapping("/hello/{name}/{age}") -> Handles HTTP GET requests and captures name and age from the URL.
• The method returns a JSON string as a response.

Step 6: Run the Spring Boot Application

• Open SpringBootApplicationDemo.java
• Right-click -> Run as Java Application
• Wait for the Spring Boot app to start on port 8080

Tip: Change the port in application.properties if needed.

Step 7: Test the API

• Open a browser or Postman
• Test the URL: http://localhost:8080/api/hello/Kadrun/24

Output: