如何创建可插入的Java程序？

public interface Plugin {
    void execute();
}

public class PluginA implements Plugin {
    @Override
    public void execute() {
        System.out.println("Plugin A is executing.");
    }
}

public class PluginB implements Plugin {
    @Override
    public void execute() {
        System.out.println("Plugin B is executing.");
    }
}

public class Main {
    public static void main(String[] args) {
        Plugin pluginA = new PluginA();
        Plugin pluginB = new PluginB();

        pluginA.execute();
        pluginB.execute();
    }
}

public class PluginLoader {
    public static void loadPlugins(String pluginDirectory) {
        File directory = new File(pluginDirectory);
        if (!directory.isDirectory()) {
            System.out.println("Plugin directory not found.");
            return;
        }

        File[] files = directory.listFiles();
        for (File file : files) {
            if (file.isFile() && file.getName().endsWith(".jar")) {
                try {
                    URL[] urls = new URL[] { file.toURI().toURL() };
                    ClassLoader classLoader = new URLClassLoader(urls);

                    Class<?> pluginClass = classLoader.loadClass("Plugin");
                    Plugin plugin = (Plugin) pluginClass.newInstance();

                    plugin.execute();
                } catch (Exception e) {
                    System.out.println("Error loading plugin: " + e.getMessage());
                }
            }
        }
    }
}