Using @Value annotation in Spring Boot

To use @Value annotation (in Spring Boot Application), we don't have to use @PropertySource annotation as we saw in this spring core tutorial. That's because Spring Boot by default reads properties from application.properties file (given that it is in classpath) or we have many other options as described here.

In this quick example, we will see how to use @Value in Spring Boot.

src/main/resources/application.properties

app.title=My Spring Application

@SpringBootConfiguration
public class ExampleMain {
    @Bean
    MyBean myBean() {
        return new MyBean();
    }

    public static void main(String[] args) throws InterruptedException {
        ApplicationContext context = SpringApplication.run(ExampleMain.class, args);
        MyBean myBean = context.getBean(MyBean.class);
        myBean.startApplication();
    }

    private static class MyBean {

        @Value("${app.title}")
        private String appTitle;

        public void startApplication() {
            System.out.printf("-- running application: %s --%n", appTitle);

        }
    }
}

Output

  .   ____          _            __ _ _
 /\\ / ___'_ __ _ _(_)_ __  __ _ \ \ \ \
( ( )\___ | '_ | '_| | '_ \/ _` | \ \ \ \
 \\/  ___)| |_)| | | | | || (_| |  ) ) ) )
  '  |____| .__|_| |_|_| |_\__, | / / / /
 =========|_|==============|___/=/_/_/_/
 :: Spring Boot ::        (v1.5.4.RELEASE)

2017-07-06 21:01:02.995  INFO 11144 --- [           main] com.logicbig.example.ExampleMain         : Starting ExampleMain on JoeMsi with PID 11144 (D:\example-projects\spring-boot\boot-value-annotation\target\classes started by Joe in D:\example-projects\spring-boot\boot-value-annotation)
2017-07-06 21:01:02.995  INFO 11144 --- [           main] com.logicbig.example.ExampleMain         : No active profile set, falling back to default profiles: default
2017-07-06 21:01:03.027  INFO 11144 --- [           main] s.c.a.AnnotationConfigApplicationContext : Refreshing org.springframework.context.annotation.AnnotationConfigApplicationContext@24b1d79b: startup date [Thu Jul 06 21:01:03 CDT 2017]; root of context hierarchy
2017-07-06 21:01:03.165  INFO 11144 --- [           main] com.logicbig.example.ExampleMain         : Started ExampleMain in 0.37 seconds (JVM running for 0.596)
-- running application: My Spring Application --
2017-07-06 21:01:03.165  INFO 11144 --- [       Thread-1] s.c.a.AnnotationConfigApplicationContext : Closing org.springframework.context.annotation.AnnotationConfigApplicationContext@24b1d79b: startup date [Thu Jul 06 21:01:03 CDT 2017]; root of context hierarchy

Example Project

Dependencies and Technologies Used:

• Spring Boot 1.5.4.RELEASE
  Corresponding Spring Version 4.3.9.RELEASE
• spring-boot-starter : Core starter, including auto-configuration support, logging and YAML.
• JDK 1.8
• Maven 3.3.9