Fork me on GitHub

Create a Piranha Embedded JLink application

Can you create a JLink application with Piranha Embedded?

In 6 steps you will learn how to so. They are:

  1. Create the Maven POM file
  2. Add the application class
  3. Add the servlet class
  4. Add the module-info
  5. Build the application
  6. Run the application

Create the Maven POM file

Create an empty directory to store your Maven project. Inside of that directory create the pom.xml file with the content as below.

<?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>cloud.piranha.guides.embedded</groupId>
    <artifactId>jlink</artifactId>
    <version>24.3.0-SNAPSHOT</version>
    <packaging>jar</packaging>
    <name>Piranha Embedded - JLink application</name>
    <properties>
        <exec-maven-plugin.version>3.2.0</exec-maven-plugin.version>
        <java.version>21</java.version>
        <jrelease-maven-plugin.version>1.10.0</jrelease-maven-plugin.version>
        <maven-compiler-plugin.version>3.12.1</maven-compiler-plugin.version>
        <maven-dependency-plugin.version>3.6.1</maven-dependency-plugin.version>
        <maven-jar-plugin.version>3.3.0</maven-jar-plugin.version>
        <piranha.version>24.2.0</piranha.version>
        <project.build.sourceEncoding>UTF-8</project.build.sourceEncoding>
        <main.class>helloworld.HelloWorldApplication</main.class>
    </properties>
    <build>
        <plugins>
            <plugin>
                <groupId>org.apache.maven.plugins</groupId>
                <artifactId>maven-compiler-plugin</artifactId>
                <version>${maven-compiler-plugin.version}</version>
                <configuration>
                    <release>${java.version}</release>
                </configuration>
            </plugin>
            <plugin>
                <groupId>org.apache.maven.plugins</groupId>
                <artifactId>maven-dependency-plugin</artifactId>
                <version>${maven-dependency-plugin.version}</version>
                <executions>
                    <execution>
                        <id>copy-dependencies</id>
                        <phase>prepare-package</phase>
                        <goals>
                            <goal>copy-dependencies</goal>
                        </goals>
                        <configuration>
                            <outputDirectory>${project.build.directory}/modules</outputDirectory>
                        </configuration>
                    </execution>
                </executions>
            </plugin>
            <plugin>
                <groupId>org.codehaus.mojo</groupId>
                <artifactId>exec-maven-plugin</artifactId>
                <version>${exec-maven-plugin.version}</version>
                <configuration>
                    <mainClass>${main.class}</mainClass>
                </configuration>
            </plugin>
            <plugin>
                <groupId>org.apache.maven.plugins</groupId>
                <artifactId>maven-jar-plugin</artifactId>
                <version>${maven-jar-plugin.version}</version>
                <configuration>
                    <archive>
                        <manifest>
                            <mainClass>${main.class}</mainClass>
                        </manifest>
                    </archive>
                </configuration>
            </plugin>
            <plugin>
                <groupId>org.jreleaser</groupId>
                <artifactId>jreleaser-maven-plugin</artifactId>
                <version>${jrelease-maven-plugin.version}</version>
                <configuration>
                    <gitRootSearch>true</gitRootSearch>
                    <jreleaser>
                        <project>
                            <description>${project.name}</description>
                            <copyright>Manorrock.com</copyright>
                        </project>
                        <assemble>
                            <jlink>
                                <helloworld>
                                    <active>ALWAYS</active>
                                    <imageName>{{distributionName}}-{{projectVersion}}</imageName>
                                    <java>
                                        <mainModule>helloworld</mainModule>
                                        <mainClass>${main.class}</mainClass>
                                    </java>
                                    <copyJars>true</copyJars>
                                    <mainJar>
                                        <path>${project.build.directory}/${project.artifactId}-${project.version}.jar</path>
                                    </mainJar>
                                    <jars>
                                        <jar>
                                            <pattern>${project.build.directory}/modules/*.jar</pattern>
                                        </jar>
                                    </jars>
                                </helloworld>
                            </jlink>
                        </assemble>
                    </jreleaser>
                </configuration>
                <executions>
                    <execution>
                        <id>assemble</id>
                        <phase>verify</phase>
                        <goals>
                            <goal>assemble</goal>
                        </goals>
                    </execution>
                </executions>
            </plugin>
        </plugins>
    </build>
    <dependencies>
        <dependency>
            <groupId>cloud.piranha</groupId>
            <artifactId>piranha-embedded</artifactId>
            <version>${piranha.version}</version>
            <scope>compile</scope>
        </dependency>
        <dependency>
            <groupId>cloud.piranha.http</groupId>
            <artifactId>piranha-http-impl</artifactId>
            <version>${piranha.version}</version>
            <scope>compile</scope>
        </dependency>
        <dependency>
            <groupId>cloud.piranha.http</groupId>
            <artifactId>piranha-http-webapp</artifactId>
            <version>${piranha.version}</version>
            <scope>compile</scope>
        </dependency>
    </dependencies>
</project>

Add the application class

Add the HelloWorldApplication class in the src/main/java directory, which allows you to configure the EmbeddedPiranha instance as well as the DefaultHttpServer instance.

package helloworld;

import cloud.piranha.embedded.EmbeddedPiranha;
import cloud.piranha.embedded.EmbeddedPiranhaBuilder;
import cloud.piranha.http.impl.DefaultHttpServer;
import cloud.piranha.http.webapp.HttpWebApplicationServerProcessor;

public class HelloWorldApplication {

    public static void main(String[] arguments) throws Exception {
        EmbeddedPiranha piranha = new EmbeddedPiranhaBuilder()
                .servlet("HelloWorld", HelloWorldServlet.class)
                .servletMapping("HelloWorld", "/*")
                .buildAndStart();
        
        DefaultHttpServer server = new DefaultHttpServer(8080, 
                new HttpWebApplicationServerProcessor(piranha), false);
        
        server.start();
    }
}

Add the servlet

And we are adding a simple HelloWorld servlet.

package helloworld;

import java.io.IOException;
import java.io.PrintWriter;
import jakarta.servlet.ServletException;
import jakarta.servlet.http.HttpServlet;
import jakarta.servlet.http.HttpServletRequest;
import jakarta.servlet.http.HttpServletResponse;

public class HelloWorldServlet extends HttpServlet {
    
    @Override
    protected void doGet(HttpServletRequest request, 
            HttpServletResponse response) throws IOException, ServletException {
        try (PrintWriter writer = response.getWriter()) {
            writer.println("Hello World");
            writer.flush();
        }
    }
}

Add the module info

Now add the module-info.java to the src/main/java directory.

module helloworld {

    exports helloworld;
    requires cloud.piranha.embedded;
    requires cloud.piranha.http.api;
    requires cloud.piranha.http.impl;
    requires cloud.piranha.http.webapp;
    requires jakarta.servlet;
}

Build the application

The following command line will build your application:

  mvn verify

Run the application

In the previous step you created the JLink custom image. To execute the application go to the target/jreleaser directory and look for the bin directory and execute the helloworld wrapper in it. And then point your browser to http://localhost:8080 to see it in action.

Conclusion

As you can see creating a JLink runtime image with Piranha Embedded is a few easy steps away!

References

  1. Piranha Embedded
  2. JReleaser