How to create an REST API in Spring boot using Java

How to Create a REST API in Spring Boot Using Java

1. Create a New Project:
   • Open your IDE and create a new project named "spring API" using Maven.
   • Add the following dependency in the pom.xml file:

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

2. Create Project Structure:
   • Inside the project, create the following folders:
     • API folder for API related files.
     • Service folder for handling backend logic.
     • Controller and Model packages inside the API folder.
3. Create User Controller and Service:
   • In the Controller package, create a new Java class for the user controller.
   • Define a basic user model with properties like userID, name, age, and email.
   • Annotate the user controller with @RestController.
   • Create a method in the controller annotated with @GetMapping to return user data based on an ID parameter.
   • In the Service folder, create a user service class to handle user-related operations.
4. Implement User Service:
   • Inject the user service into the user controller using constructor injection.
   • Implement the logic to retrieve user data based on the provided ID.
   • Create a list of users with sample data to simulate a database.
   • Return the user object or an empty optional based on the ID provided.
5. Test the API:
   • Open Postman to test the API endpoints.
   • Update the @GetMapping annotation in the controller method to include a path like /user.
   • Run the project and access the API at localhost:8080/user?id=1 to fetch user data based on the ID.
   • Test with different user IDs to verify the functionality.
6. Handling Response and Error Cases:
   • Improve the API response by handling cases where the user is not found.
   • Update the response status codes and messages for better error handling.
7. Finalize and Review:
   • Review the entire setup of the Spring-based API.
   • Understand the usage of controllers, models, services, and dependency injection.
   • Appreciate the simplicity and power of Spring Boot for creating REST APIs in Java.
8. Conclusion:
   • Spring Boot provides a powerful framework for building REST APIs quickly and efficiently.
   • The tutorial showcased a basic setup with a controller, model, and service classes.
   • Explore further functionalities and features of Spring Boot for more complex API implementations.

By following these steps, you can create a REST API in Spring Boot using Java efficiently. Experiment with different functionalities and extend the API based on your requirements.