Create a Hello World web application

If you are looking to create a simple Hello World web application with Piranha Embedded you are at the right place!

In 3 steps you will learn how to create the web application. They are:

Create the Maven POM file
Add the Hello World Servlet
Add the Hello World 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>helloworld</artifactId>
    <version>24.10.0-SNAPSHOT</version>
    <packaging>jar</packaging>
    <name>Piranha Embedded - Create a Hello World web application</name>
    <properties>
        <!-- dependencies -->
        <piranha.version>24.8.0</piranha.version>
        <!-- other -->
        <java.version>21</java.version>
        <project.build.sourceEncoding>UTF-8</project.build.sourceEncoding>
        <!-- plugins -->
        <exec-maven-plugin.version>3.4.1</exec-maven-plugin.version>
        <maven-compiler-plugin.version>3.13.0</maven-compiler-plugin.version>
        <maven-jar-plugin.version>3.4.2</maven-jar-plugin.version>
    </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.codehaus.mojo</groupId>
                <artifactId>exec-maven-plugin</artifactId>
                <version>${exec-maven-plugin.version}</version>
                <configuration>
                    <mainClass>helloworld.HelloWorldApplication</mainClass>
                </configuration>
            </plugin>
            <plugin>
                <groupId>org.apache.maven.plugins</groupId>
                <artifactId>maven-jar-plugin</artifactId>
                <version>${maven-jar-plugin.version}</version>
                <configuration>
                    <archive>
                        <manifest>
                            <mainClass>helloworld.HelloWorldApplication</mainClass>
                        </manifest>
                    </archive>
                </configuration>
            </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 Hello World Servlet

Add the HelloWorldServlet.java file in the src/main/webapp/helloworld directory.

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 Hello World application

Add the HelloWorldApplication.java file in the src/main/webapp/helloworld directory.

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();
    }
}

Conclusion

As you can see getting started with Piranha Embedded is easy!