Spring Boot packages all dependencies and an embedded web server into a single executable JAR, allowing developers to launch the application with a simple "java -jar" command without external configuration or server deployment.
This article provides a step‑by‑step technical analysis of Spring Boot's startup process, breaking down the creation of SpringApplication, the configuration of application type, initializers, listeners, and the eight phases executed by the run() method, complete with code snippets and diagrams.
This article explains how Spring Boot launches an application by creating an AnnotationConfigApplicationContext, registering annotation processors, loading the primary source class, and invoking ConfigurationClassPostProcessor during the refresh phase, with detailed code examples illustrating each step.
