Spring Boot: main

What the main program looks like in a Spring Boot Application

The main in a Spring Boot application typically looks something like this.

package com.example.hello;

import org.springframework.boot.SpringApplication;
import org.springframework.boot.autoconfigure.SpringBootApplication;

@SpringBootApplication
public class HelloApp {

  public static void main(String [] args) {
     SpringApplication.run(HelloApp.class, args)
  }  
}

You can find an example in this tutorial: https://content.pivotal.io/springone-platform-2017/its-a-kind-of-magic-under-the-covers-of-spring-boot-brian-clozel-st%C3%A9phane-nicoll

The annotation @SpringBootApplication

The annotation @SpringBootApplication is an abbreviation for three annotations:

@SpringBootConfiguration
@ComponentScan
@EnableAutoConfiguration

See: https://www.youtube.com/watch?time_continue=331&v=jDchAEHIht0

The annotation @ComponentScan

If this occurs on a class in com.example.hello, it will scan:

• com.example.hello
• subpackages of com.example.hello, e.g.
  • com.example.hello.alpha
  • com.example.hello.bravo
  • com.example.hello.charlie

But it will NOT scan:

• com.example.charlie

So the @SpringBootApplication needs to be on a class that is at the root of your package structure.