Basic plugin support

src/main/java/net/minestom/server/MinecraftServer.java

@@ -31,6 +31,7 @@ import net.minestom.server.network.packet.server.play.PluginMessagePacket;
 import net.minestom.server.network.packet.server.play.ServerDifficultyPacket;
 import net.minestom.server.particle.Particle;
 import net.minestom.server.ping.ResponseDataConsumer;
+import net.minestom.server.plugins.PluginManager;
 import net.minestom.server.potion.PotionType;
 import net.minestom.server.recipe.RecipeManager;
 import net.minestom.server.registry.ResourceGatherer;
@@ -113,6 +114,8 @@ public class MinecraftServer {
     private static DimensionTypeManager dimensionTypeManager;
     private static AdvancementManager advancementManager;
 
+    private static PluginManager pluginManager;
+
     private static UpdateManager updateManager;
     private static MinecraftServer minecraftServer;
 
@@ -166,6 +169,8 @@ public class MinecraftServer {
 
         updateManager = new UpdateManager();
 
+        pluginManager = PluginManager.getInstance();
+
         lootTableManager = new LootTableManager();
         tagManager = new TagManager();
 
@@ -300,6 +305,9 @@ public class MinecraftServer {
         MinecraftServer.responseDataConsumer = responseDataConsumer;
         updateManager.start();
         nettyServer.start(address, port);
+        long t1 = -System.nanoTime();
+        pluginManager.loadPlugins();
+        LOGGER.info("Plugins loaded in " + (t1+System.nanoTime())/1_000_000D + "ms");
         LOGGER.info("Minestom server started successfully.");
     }
 

src/main/java/net/minestom/server/plugins/Plugin.java

@@ -0,0 +1,5 @@
+package net.minestom.server.plugins;
+
+public abstract class Plugin {
+
+}

src/main/java/net/minestom/server/plugins/PluginDescription.java

@@ -0,0 +1,8 @@
+package net.minestom.server.plugins;
+
+public @interface PluginDescription {
+
+	String name();
+	String description();
+	String version();
+}

src/main/java/net/minestom/server/plugins/PluginLoader.java

@@ -0,0 +1,70 @@
+package net.minestom.server.plugins;
+
+import lombok.extern.slf4j.Slf4j;
+
+import java.io.IOException;
+import java.lang.reflect.Type;
+import java.net.URL;
+import java.net.URLClassLoader;
+import java.util.ArrayList;
+import java.util.Collections;
+import java.util.Enumeration;
+import java.util.List;
+import java.util.jar.JarEntry;
+import java.util.jar.JarFile;
+
+@Slf4j
+public class PluginLoader {
+
+	private static PluginLoader instance = null;
+
+	//Singleton
+	public static PluginLoader getInstance() {
+		if (instance == null) {
+			instance = new PluginLoader();
+		}
+		return instance;
+	}
+
+	private PluginLoader() {
+
+	}
+
+	public List<Plugin> loadPlugin(String path) {
+		JarFile jarFile;
+		URLClassLoader cl;
+		try {
+			jarFile = new JarFile(path);
+			URL[] urls = new URL[]{new URL("jar:file:" + path + "!/")};
+			cl = URLClassLoader.newInstance(urls);
+		} catch (IOException e) {
+			e.printStackTrace();
+			return new ArrayList<>();
+		}
+		final List<Plugin> plugins = new ArrayList<>();
+		final Enumeration<JarEntry> e = jarFile.entries();
+		while (e.hasMoreElements()) {
+			try {
+				final JarEntry je = e.nextElement();
+				if (je.isDirectory() || !je.getName().endsWith(".class")) continue;
+				// -6 because of .class
+				String className = je.getName().substring(0, je.getName().length() - 6);
+				className = className.replace('/', '.');
+				final Class<?> c;
+				c = cl.loadClass(className);
+				Type superclass = c.getGenericSuperclass();
+				if (superclass != null && Plugin.class.getTypeName().equals(superclass.getTypeName()))
+					try {
+						plugins.add((Plugin) c.getConstructor().newInstance());
+					} catch (final ReflectiveOperationException | ArrayIndexOutOfBoundsException ex) {
+						ex.printStackTrace();
+					}
+			} catch (final Throwable ex) {
+				ex.printStackTrace();
+			}
+		}
+
+		return Collections.unmodifiableList(plugins);
+	}
+
+}

src/main/java/net/minestom/server/plugins/PluginManager.java

@@ -0,0 +1,43 @@
+package net.minestom.server.plugins;
+
+import lombok.extern.slf4j.Slf4j;
+
+import java.io.File;
+
+@Slf4j
+public class PluginManager {
+
+	private static PluginManager instance = null;
+
+	//Singleton
+	public static PluginManager getInstance() {
+		if (instance == null) {
+			instance = new PluginManager();
+		}
+		return instance;
+	}
+
+	private final PluginLoader loader = PluginLoader.getInstance();
+
+	private final File pluginsDir;
+
+	private PluginManager() {
+		pluginsDir = new File("plugins");
+		if (!pluginsDir.exists()||!pluginsDir.isDirectory()) {
+			if (!pluginsDir.mkdir()) {
+				log.error("Couldn't create plugins dir, plugins will not be loaded.");
+				return;
+			}
+		}
+	}
+
+	public void loadPlugins() {
+
+		File[] files = pluginsDir.listFiles();
+		if(files != null) {
+			for (final File plugin : files) {
+				loader.loadPlugin(plugin.getPath());
+			}
+		}
+	}
+}