spring-boot/spring-boot

Spring Boot

Spring Boot provides the central features for the other modules in the project. It is relatively unopinionated and it has minimal dependencies which makes it usable as a stand-alone library for anyone whose tastes diverge from ours.

SpringApplication

The SpringApplication class provides a convenient way to bootstrap a Spring application that will be started from a main() method. In many situations you can just delegate to the static SpringApplication.run method:

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

When you application starts you should see something similar to the following:

  .   ____          _            __ _ _
 /\\ / ___'_ __ _ _(_)_ __  __ _ \ \ \ \
( ( )\___ | '_ | '_| | '_ \/ _` | \ \ \ \
 \\/  ___)| |_)| | | | | || (_| |  ) ) ) )
  '  |____| .__|_| |_|_| |_\__, | / / / /
 =========|_|==============|___/=/_/_/_/
 Spring Boot (v0.5.0.BUILD-SNAPSHOT)

2013-07-31 00:08:16.117  INFO 56603 --- [           main] o.s.b.s.app.SampleApplication   : Starting SampleApplication v0.1.0 on mycomputer with PID 56603 (/apps/myapp.jar started by pwebb)
2013-07-31 00:08:16.166  INFO 56603 --- [           main] ationConfigEmbeddedWebApplicationContext : Refreshing org.springframework.boot.context.embedded.AnnotationConfigEmbeddedWebApplicationContext@6e5a8246: startup date [Wed Jul 31 00:08:16 PDT 2013]; root of context hierarchy

By default INFO logging messages will shown, including some relevant startup information such as the user that started the application.

Customizing SpringApplication

If the SpringApplication defaults aren't to your taste you can instead create a local instance and customize it. For example, to turn off the banner you would write:

public static void main(String[] args) {
	SpringApplication app = new SpringApplication(SpringConfiguration.class);
	app.setShowBanner(false);
	app.run(args);
}

See the SpringApplication Javadoc for a complete list of the configuration options

Accessing command line properties

By default SpringApplication will expose any command line arguments as Spring Properties. This allows you to easily access arguments using by injecting them as @Values

import org.springframework.stereotype.*
import org.springframework.beans.factory.annotation.*

@Component
public class MyBean {
	
	@Value("${name}")
	private String name; 
	// Running 'java -jar myapp.jar --name=Spring' will set this to "Spring"

	// ...	
}

CommandLineRunner beans

If you wan't access to the raw command line argument, or you need to run some specific code once the SpringApplication has started you can implement the CommandLineRunner interface. The run(String... args) method will be called on all spring beans implementing the interface.

import org.springframework.boot.*
import org.springframework.stereotype.*

@Component
public class MyBean implements CommandLineRunner {

	public void run(String... args) {
		// Do something...
	}
	
}

You can additionally implement the org.springframework.core.Ordered interface or use the org.springframework.core.annotation.Order annotation if serveral CommandLineRunner beans are defined that must be called in a specific order.

Application Exit

Embedded Servlet Container Support

External Configuration

Conditionals

ApplicationContextInitializers