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Building a Simple Spring Boot REST API

Apr 22, 2025

Lecture Notes: Building a Simple Spring Boot REST API

Introduction

  • Video was suggested by a community poll.
  • Focus on building a simple Spring Boot REST API.
  • Exploration of dependency injection and configuration management.
  • Invitation for viewer suggestions on topics.

What is a Framework?

  • A framework is a configurable layer of code.
  • Built on top of language primitive APIs.
  • Hides tedious tasks needed to achieve useful results.
  • Example tasks: handling HTTP requests would require handling sockets and ensuring HTTP protocol compliance.
  • Web frameworks like Spring Boot, Vert.x, Micronaut, Jetty simplify this process.

Framework vs. Library

  • Library:
    • Designed primarily for code reuse.
    • Used as needed by application code.
  • Framework:
    • Acts as a structured backbone of an application.
    • Provides mechanisms for extension and abstractions.
    • Encourages following its design principles.

Why is Spring Boot Popular?

  • Part of the JVM ecosystem.
  • Easy setup for a simple REST API:
    • Import Spring Boot starter web dependency.
    • Add @SpringBootApplication annotation to the main class.
    • Use SpringApplication.run with main class and command line args.
    • Provides a REST API listening on port 8080.

Handling Requests in Spring Boot

  • GET Requests:
    • Use @RestController and @GetMapping annotations.
    • Handle dynamic content using @PathVariable.
  • POST Requests:
    • Use @PostMapping annotation.
    • Extract JSON payload into Plain Old Java Objects (POJO).

Code Design in Spring Boot

  • REST Controller Classes:
    • Define input/output contracts.
    • Specify how clients interact with the application.
  • Service Classes:
    • Handle complex logic.
    • Use @Service annotation, which registers class for dependency injection.
    • Built-in dependency injection system requires no configuration.

Dependency Injection

  • Classes to be injected need @Component annotation.
  • @Service and @RestController are based on @Component.
  • Injection is done by adding the class as a constructor parameter.

Configuration Management

  • Use application.yml for configuration.
  • Examples:
    • Change server port (server.port: 1990).
    • Configure logging.
  • Offers extensive configuration options.

Additional Resources

  • One-hour crash course on Udemy for building an end-to-end Spring Boot REST API.
  • Course connects to external HTTP API and local MySQL database.

Conclusion

  • Overview of Spring Boot framework's capabilities.
  • Encouragement for feedback and further learning.