Micronaut: Introspect a compiled class

If a class is already compiled, and not in your control, then you can define a configuration class with the classes member of the @Introspected annotation set.

@Introspected(classes = Random.class)
public class RandomConfig {

}

 

In the above example the RandomConfig class generates introspections for the Random class.

 

Find the below working application.

 

Step 1: Create new maven project ‘micronaut-introspect-compiled-class’.

 

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-introspect-compiled-class</artifactId>
	<version>1</version>

	<properties>
		<maven-compiler-plugin.version>3.8.1</maven-compiler-plugin.version>
		<micronaut.version>3.7.2</micronaut.version>
		<slf4j.version>2.0.3</slf4j.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>${micronaut.version}</version>
		</dependency>
		<dependency>
			<groupId>io.micronaut</groupId>
			<artifactId>micronaut-runtime</artifactId>
			<version>${micronaut.version}</version>
		</dependency>


		<dependency>
			<groupId>org.slf4j</groupId>
			<artifactId>slf4j-api</artifactId>
			<version>${slf4j.version}</version>
		</dependency>
		<dependency>
			<groupId>org.slf4j</groupId>
			<artifactId>slf4j-simple</artifactId>
			<version>${slf4j.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 RandomConfig class.

 

RandomConfig.java

package com.sample.app.model;

import java.util.Random;

import io.micronaut.core.annotation.Introspected;

@Introspected(classes = Random.class)
public class RandomConfig {

}

 

Step 4: Define main application class.

 

App.java

package com.sample.app;

import java.util.Random;

import io.micronaut.context.ApplicationContext;
import io.micronaut.core.beans.BeanIntrospection;

public class App {

	public static void main(String[] args) {
		try (ApplicationContext applicationContext = ApplicationContext.run()) {

			final BeanIntrospection<Random> introspection = BeanIntrospection.getIntrospection(Random.class);
			Random random = introspection.instantiate();

			System.out.println(random.nextInt());

		}

	}
}

 

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-introspect-compiled-class-1-jar-with-dependencies.jar’ in project target folder.

 

$ls ./target/
archive-tmp
classes
generated-sources
maven-archiver
maven-status
micronaut-introspect-compiled-class-1-jar-with-dependencies.jar
micronaut-introspect-compiled-class-1.jar
test-classes

 

Execute below command to run the application.

java -jar ./target/micronaut-introspect-compiled-class-1-jar-with-dependencies.jar

$java -jar ./target/micronaut-introspect-compiled-class-1-jar-with-dependencies.jar
-1997248193
$
$java -jar ./target/micronaut-introspect-compiled-class-1-jar-with-dependencies.jar
-1923410837
$
$java -jar ./target/micronaut-introspect-compiled-class-1-jar-with-dependencies.jar
-237451348
$
$java -jar ./target/micronaut-introspect-compiled-class-1-jar-with-dependencies.jar
292572176

 

You can download this application from this link.

 

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