A plugin system with maven and Java 14

IDemoModel.java

package org.wingate.demomodel;

public interface IDemoModel {
    
    public String getName();
    
}

IDemoModelPOM.xml

<?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>org.wingate</groupId>
    <artifactId>DemoModel</artifactId>
    <version>1.0</version>
    <packaging>jar</packaging>
    <properties>
        <project.build.sourceEncoding>UTF-8</project.build.sourceEncoding>
        <maven.compiler.source>14</maven.compiler.source>
        <maven.compiler.target>14</maven.compiler.target>
    </properties>
</project>

Main.java

package org.wingate.demoapp;

import java.io.File;
import java.util.ArrayList;
import java.util.List;
import java.util.Map;
import org.wingate.demomodel.IDemoModel;

public class Main {
    public static void main(String[] args) {
        List<IDemoModel> pluginsAB = new ArrayList<>();
        
        // On crée une instance du gestionnaire
        PluginsHandler ph = new PluginsHandler();
        
        // On charge les fichiers par l'intermédiare d'un dossier
        ph.load(new File("D:\\Dev\\Java\\NB-Demo\\Plugins"));
        
        // On récupère les plugins de tous les sortes, dans ce dossier
        Map<Object, String> map = ph.getPlugins();
        
        // On cherche et on affiche les noms de plugin ayant pour modèle 'IDemoModel'
        for(Map.Entry<Object, String> entry : map.entrySet()){            
            System.out.println("ENTRY : " + entry.getKey() + "; " + entry.getValue());
                        
            if(entry.getValue().contains(IDemoModel.class.getName())){
                IDemoModel test = IDemoModel.class.cast(entry.getKey());
                System.out.println("TEST (1) " + (test == null ? "fail" : "OK"));
                System.out.println("TEST (2) " + (test == null ? "fail" : test.getName()));
                
                pluginsAB.add(test);
                
                System.out.println("NB TESTS : " + pluginsAB.size());
            }
        }
    }

PluginA.java

package org.wingate.demoplugina;

import org.wingate.demomodel.IDemoModel;

public class PluginA implements IDemoModel {

    public PluginA() {
        
    }

    @Override
    public String getName() {
        return "I am the plugin A!";
    }
    
}

PluginAPOM.xml

<?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>org.wingate</groupId>
    <artifactId>DemoPluginA</artifactId>
    <version>1.0</version>
    <packaging>jar</packaging>
    <properties>
        <project.build.sourceEncoding>UTF-8</project.build.sourceEncoding>
        <maven.compiler.source>14</maven.compiler.source>
        <maven.compiler.target>14</maven.compiler.target>
    </properties>
    <dependencies>
        <dependency>
            <groupId>org.wingate</groupId>
            <artifactId>DemoModel</artifactId>
            <version>1.0</version>
        </dependency>
    </dependencies>
</project>

PluginB.java

package org.wingate.demopluginb;

import org.wingate.demomodel.IDemoModel;

public class PluginB implements IDemoModel {

    public PluginB() {
        
    }

    @Override
    public String getName() {
        return "I am the plugin B!";
    }
    
}

PluginsHandler.java

package org.wingate.demoapp;

import java.io.File;
import java.io.IOException;
import java.lang.reflect.Constructor;
import java.lang.reflect.InvocationTargetException;
import java.net.URL;
import java.net.URLClassLoader;
import java.util.Enumeration;
import java.util.HashMap;
import java.util.Map;
import java.util.jar.JarFile;
import java.util.logging.Level;
import java.util.logging.Logger;

public class PluginsHandler {
    
    private final Map<Object, String> plugins = new HashMap<>();

    public PluginsHandler() {
    }
    
    /**
     * Load one or more plugins
     * @param file a file or a folder
     */
    public void load(File file){
        File[] files = file.isDirectory() == true ? file.listFiles() : new File[]{ file };
        
        URLClassLoader loader; // Pour charger le .jar en mémoire
        String tmp; // Pour la comparaison de chaines        
        Enumeration enumeration; // Pour le contenu de l'archive jar        
        Class tmpClass; // Pour déterminer quelles sont les interfaces implémentées
        
        for(File f : files){
            try{
                URL u = f.toURI().toURL();
                
                //On crée un nouveau URLClassLoader pour charger
                // le jar qui se trouve en dehors du CLASSPATH
                loader = new URLClassLoader(new URL[] {u}); 

                // On charge le jar en mémoire
                JarFile jar = new JarFile(f.getAbsolutePath());

                // On récupère le contenu du jar
                enumeration = jar.entries();
 
                while(enumeration.hasMoreElements()){
                    tmp = enumeration.nextElement().toString();

                    // On vérifie que le fichier courant est un .class
                    // (et pas un fichier d'informations du jar )
                    if(tmp.length() > 6 && tmp.substring(tmp.length()-6).compareTo(".class") == 0) {

                        tmp = tmp.substring(0,tmp.length()-6);
                        tmp = tmp.replaceAll("/",".");

                        tmpClass = Class.forName(tmp ,true, loader);

                        for(int i = 0; i < tmpClass.getInterfaces().length; i++){
                            try{
                                Constructor ct = tmpClass.getDeclaredConstructor();
                                Object obj = ct.newInstance();
                                plugins.put(obj, tmpClass.getInterfaces()[i].toString());
                            }catch(NoSuchMethodException | SecurityException | InstantiationException |
                                    IllegalAccessException | IllegalArgumentException | InvocationTargetException ex){
                                Logger.getLogger(PluginsHandler.class.getName()).log(Level.SEVERE, null, ex);
                            }                            
                        }
                    }
                }
            }catch(IOException | ClassNotFoundException ex){

            }
        }        
    }

    public Map<Object, String> getPlugins() {
        return plugins;
    }
}

POM.xml

<?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>org.wingate</groupId>
    <artifactId>DemoApp</artifactId>
    <version>1.0</version>
    <packaging>jar</packaging>
    <properties>
        <project.build.sourceEncoding>UTF-8</project.build.sourceEncoding>
        <maven.compiler.source>14</maven.compiler.source>
        <maven.compiler.target>14</maven.compiler.target>
    </properties>
    <dependencies>
        <dependency>
            <groupId>org.wingate</groupId>
            <artifactId>DemoModel</artifactId>
            <version>1.0</version>
        </dependency>
    </dependencies>
</project>

PublicBPOM.xml

<?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>org.wingate</groupId>
    <artifactId>DemoPluginB</artifactId>
    <version>1.0</version>
    <packaging>jar</packaging>
    <properties>
        <project.build.sourceEncoding>UTF-8</project.build.sourceEncoding>
        <maven.compiler.source>14</maven.compiler.source>
        <maven.compiler.target>14</maven.compiler.target>
    </properties>
    <dependencies>
        <dependency>
            <groupId>org.wingate</groupId>
            <artifactId>DemoModel</artifactId>
            <version>1.0</version>
        </dependency>
    </dependencies>
</project>