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.