การกำหนดค่าอัตโนมัติของ Spring Boot

Welcome to Auto-Configuration — Spring Boot's behind-the-scenes magic. It inspects your project, guesses what you need, and sets it up so you skip manual wiring.

It runs on smart defaults: Spring Boot scans your classpath and applies sensible config. Add Tomcat, get a web server; add H2, get an in-memory DB — only where you haven't.

The engine behind it is @EnableAutoConfiguration (bundled in @SpringBootApplication). It tells Spring Boot to hunt for auto-config classes from the libraries on your classpath.

Starters like spring-boot-starter-web bundle the libraries AND their auto-config classes. One dependency lights up a whole feature with almost no effort.

Building a web app the old way meant manually configuring Tomcat and a dispatcher. With spring-boot-starter-web, Spring Boot detects and wires it all — you just write the logic.

Auto-configuration in action: this app starts a web server and answers /hello with zero explicit Tomcat or MVC setup.

Defaults are great, but you'll often tweak them. application.properties (or .yml) is your override file — Spring Boot reads it at startup and applies your settings.

Spring Boot web apps default to port 8080. To switch to 9090, drop a line in application.properties under src/main/resources.

Sometimes you want to disable a specific auto-config — say, when you wire your own database. Use the exclude attribute on @SpringBootApplication or set spring.autoconfigure.exclude.

Recap: auto-configuration applies smart defaults by detecting classpath dependencies, driven by @EnableAutoConfiguration, and you override it via application.properties or .yml.