[JAVA] Switching beans by profile annotation in Spring

Use the spring profile mechanism to switch between dynamically injected beans.

For the time being, create a suitable spring-boot project.

pom.xml

<project xmlns="http://maven.apache.org/POM/4.0.0" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
	xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd">
	<modelVersion>4.0.0</modelVersion>
	<groupId>hoge</groupId>
	<artifactId>springbootexpr2</artifactId>
	<version>0.0.1-SNAPSHOT</version>
	<name>springbootexpr2</name>

	<parent>
		<groupId>org.springframework.boot</groupId>
		<artifactId>spring-boot-starter-parent</artifactId>
		<version>1.5.7.RELEASE</version>
	</parent>
	<dependencies>
		<dependency>
			<groupId>org.springframework.boot</groupId>
			<artifactId>spring-boot-starter-web</artifactId>
		</dependency>
	</dependencies>
</project>

Create an appropriate interface and create some implementation classes for it.

public interface ProfileSample {
	String getValue();
}

@Component
@Profile("default")
public class DefaultProfile implements ProfileSample {

	public String getValue() {
		return "default";
	}

}

The default value for profile is `` `default```. Therefore, if you specify that value in profile annotation, this class will be used when profile is not specified.

@Component
@Profile("dev")
public class DevProfile implements ProfileSample {

	public String getValue() {
		return "dev";
	}

}

@Component
@Profile("production")
public class ProductionProfile implements ProfileSample {

	public String getValue() {
		return "production";
	}

}

Inject the interface created above into the startup class.

@Controller
@EnableAutoConfiguration
@ComponentScan
public class SampleController {

	@Autowired
	ProfileSample sample;

	@RequestMapping("/")
	@ResponseBody
	String home() {
		System.out.println(sample.getValue());
		return "Hello World!";
	}

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

After that, if you specify the spring.profiles.active property somewhere, that profile will be used, and if it is not specified, `` `default``` will be used as mentioned above.

The profile specification looks like this with command line arguments.

--spring.profiles.active=dev

When specifying in a property file, for example application.yaml, it looks like this.

application.yaml

spring.profiles.active: production

By the way, there are many ways to specify properties, so for the list and priority, see https://docs.spring.io/spring-boot/docs/2.0.0.M4/reference/htmlsingle/#boot-features-external-config

For the contents of this example, the default method of interface may be sufficient.