Download as PDF, PPTX
![package com.example.hello;
import org.springframework.boot.SpringApplication;
import org.springframework.boot.autoconfigure.SpringBootApplication;
public class HelloApp {
public static void main(String[] args) {
SpringApplication.run(HelloApp.class, args);
}
}
@SpringBootApplication](https://image.slidesharecdn.com/itsakindofmagicunderthecoversofspringboot-171219174441/75/It-s-a-Kind-of-Magic-Under-the-Covers-of-Spring-Boot-3-2048.jpg)
![package com.example.hello;
import org.springframework.boot.SpringApplication;
import org.springframework.boot.autoconfigure.SpringBootApplication;
public class HelloApp {
public static void main(String[] args) {
SpringApplication.run(HelloApp.class, args);
}
}
@SpringBootApplication](https://image.slidesharecdn.com/itsakindofmagicunderthecoversofspringboot-171219174441/75/It-s-a-Kind-of-Magic-Under-the-Covers-of-Spring-Boot-4-2048.jpg)
Uploaded byVMware Tanzu
It's a Kind of Magic: Under the Covers of Spring Boot
The document discusses various aspects of Spring Boot application development, including basic application setup, auto-configuration, custom conditions, and startup performance optimization tips. It covers annotations such as @SpringBootApplication and various configuration techniques to manage beans effectively. Additionally, the document addresses common issues faced during application startup and offers solutions to enhance performance.
More Related Content
Similar to It's a Kind of Magic: Under the Covers of Spring Boot
![[DevFest Strasbourg 2025] - NodeJs Can do that !!](https://cdn.slidesharecdn.com/ss_thumbnails/devfeststrasbourg2025-nodejscandothat-251127142731-da65b6fd-thumbnail.jpg?width=640&height=640&fit=bounds)
![[BDD 2025 - Full-Stack Development] The Modern Stack: Building Web & AI Appli...](https://cdn.slidesharecdn.com/ss_thumbnails/fs-themodernstackbuildingwebaiapplicationswithserverless-251124030844-388cf04f-thumbnail.jpg?width=640&height=640&fit=bounds)
![[BDD 2025 - Artificial Intelligence] AI for the Underdogs: Innovation for Sma...](https://cdn.slidesharecdn.com/ss_thumbnails/ai-aifortheunderdogsinnovationforsmallbusinesses-251124030839-72a599a4-thumbnail.jpg?width=640&height=640&fit=bounds)
![Support, Monitoring, Continuous Improvement & Scaling Agentic Automation [3/3]](https://cdn.slidesharecdn.com/ss_thumbnails/agenticcommunityseries-day3-cfd-251120170304-ddef8112-thumbnail.jpg?width=640&height=640&fit=bounds)
It's a Kind of Magic: Under the Covers of Spring Boot
- 1. It’s a Kindof Magic Under the Covers of Spring Boot Stéphane Nicoll Brian Clozel @snicoll @bclozel 1
- 2.
- 3. package com.example.hello; import org.springframework.boot.SpringApplication; importorg.springframework.boot.autoconfigure.SpringBootApplication; public class HelloApp { public static void main(String[] args) { SpringApplication.run(HelloApp.class, args); } } @SpringBootApplication
- 4. package com.example.hello; import org.springframework.boot.SpringApplication; importorg.springframework.boot.autoconfigure.SpringBootApplication; public class HelloApp { public static void main(String[] args) { SpringApplication.run(HelloApp.class, args); } } @SpringBootApplication
- 5.
- 6.
- 7.
- 8.
- 9. @ComponentScan com.example.hello ✓ com.example.hello.alpha ✓ com.example.hello.bravo✓ com.example.charlie 𐄂
- 10. @ComponentScan com.example.hello ✓ com.example.hello.alpha ✓ com.example.hello.bravo✓ com.example.hello.charlie ✓
- 11.
- 12.
- 13.
- 14.
- 15. @SpringBootApplication public class HelloApp{ public HelloService helloService() { return new ConsoleHelloService("Howdy", "!"); } //… } @Bean public class HelloCommandLineRunner implements CommandLineRunner { // … } @Component
- 16.
- 17.
- 20.
- 21.
- 22. @ComponentScan @EnableAutoConfiguration User configurationAuto configuration
- 23.
- 24.
- 25.
- 26. package ; import hello.ConsoleHelloService; importhello.HelloService; import org.springframework.context.annotation.Bean; import org.springframework.context.annotation.Configuration; @Configuration public class { @Bean public HelloService helloService() { return new ConsoleHelloService(); } } HelloAutoConfiguration hello.autoconfigure
- 27.
- 28. package hello.autoconfigure; import hello.ConsoleHelloService; importhello.HelloService; import org.springframework.boot.autoconfigure.condition.ConditionalOnClass; import org.springframework.boot.autoconfigure.condition.ConditionalOnMissingBean; import org.springframework.context.annotation.Bean; import org.springframework.context.annotation.Configuration; @Configuration (HelloService.class) public class HelloAutoConfiguration { @Bean public HelloService helloService() { return new ConsoleHelloService(); } } @ConditionalOnClass @ConditionalOnMissingBean
- 29.
- 30.
- 31.
- 32.
- 33.
- 34.
- 35.
- 36.
- 37.
- 38.
- 39.
- 40.
- 41.
- 42. CharlieAutoConfiguration AlphaAutoConfiguration DeltaAutoConfiguration BravoAutoConfiguration @Configuration @Configuration @Configuration @Configuration @ConditionalOn… @ConditionalOn… @ConditionalOn… @ConditionalOn… @ConditionalOn… ✓ @ConditionalOn…𐄂 𐄂@ConditionalOn… ✓ @ConditionalOn… ✓ ✓ @ConditionalOn… 𐄂 𐄂
- 43.
- 44.
- 45. class { } CharlieAutoConfiguration @Configuration @ConditionalOn… @ConditionalOn… @ConditionalOn… @Bean public Foofoo() { return new Foo(); } @ConditionalOn… ✓ ✓
- 46.
- 47.
- 48.
- 49.
- 50.
- 51. 27 😴 + ☕= 😃
- 52.
- 53. @Configuration class DataAccessAutoConfiguration { @Bean @ConditionalOnSingleCandidate(JdbcTemplate.class) publicDataAccess dataAccess(JdbcTemplate jdbc) { return new DataAccess(jdbc); } }
- 54. @Configuration class DataSourceAutoConfiguration { @Bean publicDataSource dataSource() { return new DataSource(); } }
- 55. @Configuration class JdbcAutoConfiguration { @Bean @ConditionalOnSingleCandidate(DataSource.class) publicJdbcTemplate jdbcTemplate(DataSource ds) { return new JdbcTemplate(ds); } }
- 56.
- 57.
- 58.
- 59.
- 60.
- 61.
- 62.
- 63.
- 64.
- 65. @Configuration class GsonAutoConfiguration { @Bean publicGson gson() { return new Gson(); } } @ConditionalOnClass(Gson.class)
- 66. @Configuration class GsonAutoConfiguration { @Bean publicGson gson() { return new Gson(); } } @ConditionalOnClass(Gson.class) 𐄂
- 67. @Configuration class GsonAutoConfiguration { @Bean publicGson gson() { return new Gson(); } } @ConditionalOnClass(Gson.class)
- 68. @ComponentScan @EnableAutoConfiguration User configurationAuto configuration
- 69. @Configuration public class AppConfiguration{ @Bean @ConditionalOnMissingBean public CustomBean customBean() { return new CustomBean(); } }
- 70. @Configuration public class AppConfiguration{ @Bean @ConditionalOnMissingBean public CustomBean customBean() { return new CustomBean(); } } 𐄂
- 71.
- 72.
- 73. ApplicationStartingEvent ApplicationEnvironment PreparedEvent Logging initialization begins Configfiles are read Environment post processors are called Logging initialization completes Run the application! ApplicationPreparedEvent
- 74. Logging initialization completes ApplicationPreparedEvent Applicationcontext is refreshed ContextRefreshedEvent Embedded servlet container connectors are started EmbeddedServletContainer InitializedEvent ApplicationReadyEvent CommandLineRunners and ApplicationRunners are called
- 75.
- 76.
- 77.
- 79. at org.springframework.beans.factory.support.DefaultListableBeanFactory.doResolveDepe… at org.springframework.beans.factory.support.DefaultListableBeanFactory.resolveDepend… atorg.springframework.beans.factory.annotation.AutowiredAnnotationBeanPostProcessor$… ... 226 common frames omitted Caused by: org.springframework.beans.factory.BeanCreationException: Could not autowire fi… at org.springframework.beans.factory.annotation.AutowiredAnnotationBeanPostProcessor$… at org.springframework.beans.factory.annotation.InjectionMetadata.inject(InjectionMet… at org.springframework.beans.factory.annotation.AutowiredAnnotationBeanPostProcessor.… ... 246 common frames omitted Caused by: org.springframework.beans.factory.BeanCurrentlyInCreationException: Error crea… at org.springframework.beans.factory.support.DefaultSingletonBeanRegistry.beforeSingl… at org.springframework.beans.factory.support.DefaultSingletonBeanRegistry.getSingleto… at org.springframework.beans.factory.support.AbstractBeanFactory.doGetBean(AbstractBe… at org.springframework.beans.factory.support.AbstractBeanFactory.getBean(AbstractBean… at org.springframework.beans.factory.support.DefaultListableBeanFactory.findAutowireC… at org.springframework.beans.factory.support.DefaultListableBeanFactory.doResolveDepe… at org.springframework.beans.factory.support.DefaultListableBeanFactory.resolveDepend… at org.springframework.beans.factory.annotation.AutowiredAnnotationBeanPostProcessor$… ... 248 common frames omitted
- 80.
- 81. The dependencies ofsome of the beans in the application context form a cycle: org.springframework.boot.autoconfigure.web.WebMvcAutoConfiguration$WebMvcAutoConfigura… ! org.springframework.boot.autoconfigure.web.HttpMessageConvertersAutoConfiguration (fie… ! mappingJackson2HttpMessageConverter defined in class path resource [org/springframewor… "#####$ | objectMapper defined in class path resource [org/springframework/boot/autoconfigure/da… ↑ ! | config defined in class path resource [org/springframework/boot/autoconfigure/data/res… ↑ ! | repositories defined in class path resource [org/springframework/boot/autoconfigure/da… ↑ ! | testRepository ↑ ! | (inner bean)#3567d7b4 ↑ ! | org.springframework.boot.autoconfigure.orm.jpa.HibernateJpaAutoConfiguration (field pr… ↑ ! | org.springframework.boot.autoconfigure.jdbc.JndiDataSourceAutoConfiguration (field pri… ↑ ! | org.springframework.boot.actuate.autoconfigure.EndpointMBeanExportAutoConfiguration (f… %#####&
- 82.
- 83.
- 85. “My app takesa lot of time to start”
- 86. “Classpath scanning isslow” “My app takes a lot of time to start”
- 87. “Classpath scanning isslow” “My app takes a lot of time to start” 🤔
- 88. Question: A Spring Bootapplication (with 200 beans) takes 6.5 seconds to start. How long does classpath scanning take?
- 89. Question: A Spring Bootapplication (with 200 beans) takes 6.5 seconds to start. How long does classpath scanning take? a) 1.5 sec b) 1 sec c) 500 ms d) 100 ms
- 90. Question: A Spring Bootapplication (with 200 beans) takes 6.5 seconds to start. How long does classpath scanning take? a) 1.5 sec b) 1 sec c) 500 ms d) 100 ms🤗
- 91.
- 92.
- 93.
- 95. “My app *still*takes a lot of time to start”
- 96. “My app *still*takes a lot of time to start” 😕
- 97. @SpringDeveloper Strange behavior onmacOS: Spring Boot app taking up to 13 secs to start. Run iTunes. App starts in 1-2 secs.
- 98. a) iTunes isgreat @SpringDeveloper Strange behavior on macOS: Spring Boot app taking up to 13 secs to start. Run iTunes. App starts in 1-2 secs.
- 99. a) iTunes isgreat b) @StartFasterWithITunes @SpringDeveloper Strange behavior on macOS: Spring Boot app taking up to 13 secs to start. Run iTunes. App starts in 1-2 secs.
- 100. a) iTunes isgreat b) @StartFasterWithITunes c) localhost DNS resolution in macOS Sierra @SpringDeveloper Strange behavior on macOS: Spring Boot app taking up to 13 secs to start. Run iTunes. App starts in 1-2 secs.
- 101. a) iTunes isgreat b) @StartFasterWithITunes c) localhost DNS resolution in macOS Sierra @SpringDeveloper Strange behavior on macOS: Spring Boot app taking up to 13 secs to start. Run iTunes. App starts in 1-2 secs.
- 102. • Network configuration •Antivirus • Lack of entropy, use "urandom" (fixed in SB 1.4, see #6229) • Static code initialization • Use the JVM "noverify" flag • See: https://github.com/dsyer/spring-boot-startup-bench Startup performance: (not so) usual suspects
- 103. Thank you! Stéphane NicollBrian Clozel @snicoll @bclozel
- 104. Thank you! https://github.com/snicoll-demos/hello-service-auto-configuration Stéphane NicollBrian Clozel @snicoll @bclozel