ServiceLoader Maven Plugin Example

Demonstrating the use of the serviceloader-maven-plugin for seamless ServiceLoader auto service discovery in a Maven multi-module project.

I fell back to this after failing to make the conventional JDK service auto discovery work as expected in a multi-module Maven project

Key Components

1. Service Module

Defines the TextService interface.

public interface TextService {
  String process(String text);
}

2. Provider Module

Implements UpperCaseTextService, transforming text to uppercase.

public class UpperCaseTextService implements TextService {
  @Override
  public String process(String text) {
    return text == null ? null : text.toUpperCase();
  }
}

3. Consumer Module POM

Configures Maven build for the consumer module as a service consumer, dynamically discovering implementations.

<!-- consumer/pom.xml -->
<!-- Dependencies -->
<dependency>
    <groupId>${project.groupId}</groupId>
    <artifactId>service</artifactId>
    <version>${project.version}</version>
</dependency>
<dependency>
    <groupId>${project.groupId}</groupId>
    <artifactId>provider</artifactId>
    <version>${project.version}</version>
    <scope>runtime</scope>
</dependency>

<!-- Properties -->
<properties>
    <exec.mainClass>com.github.idelstak.consumer.Consumer</exec.mainClass>
    <deps.dir>libs</deps.dir>
</properties>

<!-- Build Plugins -->
<build>
    <plugins>
        <!-- maven-compiler-plugin -->
        <!-- maven-dependency-plugin -->
        <!-- maven-jar-plugin -->
    </plugins>
</build>

Runtime Dependency

• provider module: Runtime dependency for dynamic service discovery. Scope set to runtime to avoid compile-time transitive dependencies.

Runtime dependency on provider is crucial for ServiceLoader to dynamically discover and load TextService implementations during execution.

Parent POM

Configures the serviceloader-maven-plugin at the parent level for effective service discovery across modules.