Micronaut: @Any: Inject any bean

In my previous post, I explained how to specify a primary bean in the case of multiple interface implementations using @Primary annotation.

 

But in case, if you are not particular about the bean to be injected, then you can use the @Any qualifier which will inject the first available bean.

public interface Dog {

	String aboutMe();
}

 

I have two implementations of Dog interface.

@Singleton
public class BullDog implements Dog {

	@Override
	public String aboutMe() {
		return "Bull Dog";
	}

}

@Singleton
public class PoodleDog implements Dog {

	@Override
	public String aboutMe() {
		return "Poodle Dog";
	}

}

Use @Any, if you are not particular about the bean to be injected (BullDog, PoodleDog).

@Singleton
public class DogService {

	@Inject
	@Any
	private Dog dog1;

}

Find the below working application.

Step 1: Create new maven project ‘micronaut-any-annotation-demo’.

 

Step 2: Update pom.xml with maven dependencies.

 

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 https://maven.apache.org/xsd/maven-4.0.0.xsd">
	<modelVersion>4.0.0</modelVersion>
	<groupId>com.sample.app</groupId>
	<artifactId>micronaut-any-annotation-demo</artifactId>
	<version>1</version>

	<properties>
		<maven-compiler-plugin.version>3.8.1</maven-compiler-plugin.version>
		<micronaut.version>3.7.1</micronaut.version>

		<maven.compiler.target>15</maven.compiler.target>
		<maven.compiler.source>15</maven.compiler.source>
	</properties>

	<dependencies>

		<dependency>
			<groupId>io.micronaut</groupId>
			<artifactId>micronaut-inject-java</artifactId>
			<version>${micronaut.version}</version>
		</dependency>
	</dependencies>

	<build>
		<plugins>

			<plugin>
				<artifactId>maven-assembly-plugin</artifactId>
				<configuration>
					<archive>
						<manifest>
							<mainClass>com.sample.app.App</mainClass>
						</manifest>
					</archive>
					<descriptorRefs>
						<descriptorRef>jar-with-dependencies</descriptorRef>
					</descriptorRefs>
				</configuration>

				<executions>
					<execution>
						<id>make-assembly</id>
						<phase>package</phase>
						<goals>
							<goal>single</goal>
						</goals>
					</execution>
				</executions>
			</plugin>

		</plugins>
	</build>
</project>

Step 3: Define Dog interface.

 

Dog.java

package com.sample.app.interfaces;

public interface Dog {

	String aboutMe();
}

Step 4: Define BullDog and PoodleDog classes.

 

BullDog.java

package com.sample.app.models;

import com.sample.app.interfaces.Dog;

import jakarta.inject.Singleton;

@Singleton
public class BullDog implements Dog {

	@Override
	public String aboutMe() {
		return "Bull Dog";
	}

}

PoodleDog.java

package com.sample.app.models;

import com.sample.app.interfaces.Dog;

import jakarta.inject.Singleton;

@Singleton
public class PoodleDog implements Dog {

	@Override
	public String aboutMe() {
		return "Poodle Dog";
	}

}

Step 5: Define DogService class.

 

DogService.java

package com.sample.app.service;

import com.sample.app.interfaces.Dog;

import io.micronaut.context.annotation.Any;
import jakarta.inject.Inject;
import jakarta.inject.Singleton;

@Singleton
public class DogService {

	@Inject
	@Any
	private Dog dog1;

	public void aboutMe() {

		System.out.println(dog1.aboutMe());

	}

}

Step 6: Define main application class.

 

App.java

package com.sample.app;

import com.sample.app.service.DogService;

import io.micronaut.context.ApplicationContext;

public class App {

	public static void main(String[] args) {
		try (ApplicationContext context = ApplicationContext.run()) {
			DogService animalUtil = context.getBean(DogService.class);
			animalUtil.aboutMe();
		}
	}
}

Total project structure looks like below.

 

Build the project using mvn package command.

Navigate to the folder where pom.xml is located and execute the command ‘mvn package’.

 

Upon command successful execution, you can see the jar file ‘micronaut-any-annotation-demo-1-jar-with-dependencies.jar’ in project target folder.

$ls ./target/
archive-tmp
classes
generated-sources
maven-archiver
maven-status
micronaut-any-annotation-demo-1-jar-with-dependencies.jar
micronaut-any-annotation-demo-1.jar
test-classes

Run jar file by executing below command.

java -jar ./target/micronaut-any-annotation-demo-1-jar-with-dependencies.jar

$java -jar ./target/micronaut-any-annotation-demo-1-jar-with-dependencies.jar
SLF4J: Failed to load class "org.slf4j.impl.StaticLoggerBinder".
SLF4J: Defaulting to no-operation (NOP) logger implementation
SLF4J: See http://www.slf4j.org/codes.html#StaticLoggerBinder for further details.
Bull Dog

You can download this application from this link.

 

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