springspring-bootaws-lambdamicronautapplicationcontext

Micronaut equivalence of Spring ApplicationContextAware


In Spring Boot, we have ApplicationContextAware interface, providing a way to set ApplicationContext, which is then used to inject some beans (that can only be initiated by the programme) into the class

// this is a Spring Boot programme
package com.example.demo

import org.springframework.context.ApplicationContextAware;

public class MyClass implements ApplicationContextAware {

    private MyBean myBean;
    private ApplicationContext applicationContext;

    @Override
    public void setApplicationContext(ApplicationContext applicationContext) {
        this.applicationContext= applicationContext;
    }

    public void setBean(){
       this.myBean= applicationContext.getBean(MyBean.class);
    }
}

I was trying to find such a method in Micronaut framework. I looked into documentation and tried a few classes like ApplicationContextConfigurer, ApplicationContextBuilder etc. but none seemed to work

By looking at what the code above does, is there a way to achieve the same thing in Micronaut?


More background:

I deployed a Micronaut application onto AWS Lambda and got NullPointerException. I referred to this post, which mentioned ApplicationContextAware. This post uses Spring, but I suspect the underlysing mechanism should be similar


Posting my pom.xml, as asked by the comments

<?xml version="1.0" encoding="UTF-8"?>
<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>com.example</groupId>
  <artifactId>MicronautExp</artifactId>
  <version>0.1</version>
  <packaging>${packaging}</packaging>

  <parent>
    <groupId>io.micronaut</groupId>
    <artifactId>micronaut-parent</artifactId>
    <version>3.7.4</version>
  </parent>

  <properties>
    <packaging>jar</packaging>
    <jdk.version>11</jdk.version>
    <release.version>11</release.version>
    <micronaut.version>3.7.4</micronaut.version>
    <micronaut.runtime>netty</micronaut.runtime>
    <micronaut.runtime>lambda</micronaut.runtime>
    <exec.mainClass>com.example.Application</exec.mainClass>
    <exec.mainClass>io.micronaut.function.aws.runtime.MicronautLambdaRuntime</exec.mainClass>
  </properties>

  <repositories>
    <repository>
      <id>central</id>
      <url>https://repo.maven.apache.org/maven2</url>
    </repository>
  </repositories>

  <dependencies>
    <dependency>
      <groupId>io.micronaut</groupId>
      <artifactId>micronaut-inject</artifactId>
      <scope>compile</scope>
    </dependency>
    <dependency>
      <groupId>io.micronaut</groupId>
      <artifactId>micronaut-validation</artifactId>
      <scope>compile</scope>
    </dependency>
    <dependency>
      <groupId>io.micronaut</groupId>
      <artifactId>micronaut-jackson-databind</artifactId>
      <scope>compile</scope>
    </dependency>
    <dependency>
      <groupId>jakarta.annotation</groupId>
      <artifactId>jakarta.annotation-api</artifactId>
      <scope>compile</scope>
    </dependency>
    <dependency>
      <groupId>ch.qos.logback</groupId>
      <artifactId>logback-classic</artifactId>
      <scope>runtime</scope>
    </dependency>
    <dependency>
      <groupId>io.micronaut.test</groupId>
      <artifactId>micronaut-test-junit5</artifactId>
      <scope>test</scope>
    </dependency>
    <dependency>
      <groupId>org.junit.jupiter</groupId>
      <artifactId>junit-jupiter-api</artifactId>
      <scope>test</scope>
    </dependency>
    <dependency>
      <groupId>org.junit.jupiter</groupId>
      <artifactId>junit-jupiter-engine</artifactId>
      <scope>test</scope>
    </dependency>
    <dependency>
      <groupId>org.projectlombok</groupId>
      <artifactId>lombok</artifactId>
      <version>1.18.24</version>
    </dependency>
    <dependency>
      <groupId>com.googlecode.json-simple</groupId>
      <artifactId>json-simple</artifactId>
      <version>1.1.1</version>
    </dependency>

<!--    micronaut http dependencies. Forgot why they are here, but better not touch it-->
    <dependency>
      <groupId>io.micronaut</groupId>
      <artifactId>micronaut-http-client</artifactId>
      <scope>compile</scope>
    </dependency>
    <dependency>
      <groupId>io.micronaut</groupId>
      <artifactId>micronaut-http-server-netty</artifactId>
      <scope>compile</scope>
    </dependency>

<!--    graalvm compilers. Forgot why they are here, but better not touch it-->
    <dependency>
      <groupId>org.graalvm.nativeimage</groupId>
      <artifactId>svm</artifactId>
      <version>22.2.0</version>
    </dependency>
    <dependency>
      <groupId>org.graalvm.sdk</groupId>
      <artifactId>graal-sdk</artifactId>
      <version>22.2.0</version>
    </dependency>

<!--    micronaut email dependency-->
    <dependency>
      <groupId>io.micronaut.email</groupId>
      <artifactId>micronaut-email-javamail</artifactId>
    </dependency>
    <dependency>
      <groupId>io.micronaut.email</groupId>
      <artifactId>micronaut-email</artifactId>
      <version>1.5.0</version>
    </dependency>

<!--    AWS Lambda dependencies-->
    <dependency>
      <groupId>com.amazonaws</groupId>
      <artifactId>aws-lambda-java-core</artifactId>
      <version>1.2.2</version>
    </dependency>
    <dependency>
      <groupId>io.micronaut.aws</groupId>
      <artifactId>micronaut-function-aws-api-proxy</artifactId>
      <scope>compile</scope>
    </dependency>
    <dependency>
      <groupId>io.micronaut.aws</groupId>
      <artifactId>micronaut-function-aws-api-proxy-test</artifactId>
      <scope>test</scope>
    </dependency>
    <dependency>
      <groupId>io.micronaut.aws</groupId>
      <artifactId>micronaut-function-aws-custom-runtime</artifactId>
      <scope>compile</scope>
    </dependency>

    <dependency>
      <groupId>org.apache.commons</groupId>
      <artifactId>commons-lang3</artifactId>
      <version>3.12.0</version>
    </dependency>

  </dependencies>

  <build>
    <plugins>
      <plugin>
        <groupId>io.micronaut.build</groupId>
        <artifactId>micronaut-maven-plugin</artifactId>
      </plugin>

      <plugin>
        <groupId>org.apache.maven.plugins</groupId>
        <artifactId>maven-compiler-plugin</artifactId>
        <version>3.10.1</version>
        <configuration>
          <!-- Uncomment to enable incremental compilation -->
          <!-- <useIncrementalCompilation>false</useIncrementalCompilation> -->

          <annotationProcessorPaths combine.children="append">
            <path>
              <groupId>io.micronaut</groupId>
              <artifactId>micronaut-http-validation</artifactId>
              <version>${micronaut.version}</version>
            </path>
          </annotationProcessorPaths>
          <compilerArgs>
            <arg>-Amicronaut.processing.group=com.example</arg>
            <arg>-Amicronaut.processing.module=MicronautExp</arg>
          </compilerArgs>
        </configuration>
      </plugin>

      <plugin>
        <groupId>org.apache.maven.plugins</groupId>
        <artifactId>maven-shade-plugin</artifactId>
        <version>2.4.3</version>
        <configuration>
          <createDependencyReducedPom>false</createDependencyReducedPom>
        </configuration>
        <executions>
          <execution>
            <phase>package</phase>
            <goals>
              <goal>shade</goal>
            </goals>
          </execution>
        </executions>
      </plugin>
    </plugins>
  </build>

</project>

Solution

  • In Micronaut you don't need such an interface. If any Micronaut managed bean accepts the ApplicationContext as a constructor parameter, or includes a property marked with @Inject, the ApplicationContext will be injected.

    Ex:

    import io.micronaut.context.ApplicationContext;
    import io.micronaut.http.annotation.*;
    
    @Controller("/demo")
    public class DemoController {
    
        private final ApplicationContext applicationContext;
    
        public DemoController(ApplicationContext applicationContext) {
            this.applicationContext = applicationContext;
        }
    
        @Get(uri="/", produces="text/plain")
        public String index() {
            // ...
        }
    }