dynamic library loading (500kb jar :o)

plugin/build.gradle

@@ -17,17 +17,18 @@ processResources {
 
 dependencies {
     compileOnly "me.clip:placeholderapi:2.11.3" // Placeholder support
-    implementation "com.google.code.gson:gson:2.10.1" // JSON parsing
+    compileOnly "com.google.code.gson:gson:2.10.1" // JSON parsing
-    implementation "org.bstats:bstats-bukkit:3.0.2" // Plugin stats
+    compileOnly "org.bstats:bstats-bukkit:3.0.2" // Plugin stats
-    implementation "com.github.robertlit:SpigotResourcesAPI:2.0" // Spigot API wrapper for update checker
+    compileOnly "com.github.robertlit:SpigotResourcesAPI:2.0" // Spigot API wrapper for update checker
-    implementation "com.github.retrooper.packetevents:spigot:2.1.0-SNAPSHOT" // Packets
+    compileOnly "com.github.retrooper.packetevents:spigot:2.1.0-SNAPSHOT" // Packets
-    implementation "space.arim.dazzleconf:dazzleconf-ext-snakeyaml:1.2.1" // Configs
+    compileOnly "space.arim.dazzleconf:dazzleconf-ext-snakeyaml:1.2.1" // Configs
-    implementation "lol.pyr:director-adventure:2.1.1" // Commands
+    compileOnly "lol.pyr:director-adventure:2.1.1" // Commands
 
     // Fancy text library
-    implementation "net.kyori:adventure-platform-bukkit:4.3.0"
+    compileOnly "net.kyori:adventure-platform-bukkit:4.3.1"
-    implementation "net.kyori:adventure-text-minimessage:4.14.0"
+    compileOnly "net.kyori:adventure-text-minimessage:4.14.0"
 
+    implementation "me.lucko:jar-relocator:1.7"
     implementation project(":api")
 }
 
@@ -35,6 +36,10 @@ shadowJar {
     archivesBaseName = "ZNPCsPlus"
     archiveClassifier.set ""
 
+    relocate "org.objectweb.asm", "lol.pyr.znpcsplus.lib.asm"
+    relocate "me.lucko.jarrelocator", "lol.pyr.znpcsplus.lib.jarrelocator"
+
+    // When changing anything here remember to also update the bootstrap
     relocate "org.bstats", "lol.pyr.znpcsplus.lib.bstats"
     relocate "me.robertlit.spigotresources", "lol.pyr.znpcsplus.lib.spigotresources"
     relocate "net.kyori", "lol.pyr.znpcsplus.lib.kyori"

plugin/src/main/java/lol/pyr/znpcsplus/ZNpcsPlus.java

@@ -40,8 +40,8 @@ import lol.pyr.znpcsplus.scheduling.TaskScheduler;
 import lol.pyr.znpcsplus.skin.cache.MojangSkinCache;
 import lol.pyr.znpcsplus.skin.cache.SkinCacheCleanTask;
 import lol.pyr.znpcsplus.tasks.HologramRefreshTask;
-import lol.pyr.znpcsplus.tasks.ViewableHideOnLeaveListener;
 import lol.pyr.znpcsplus.tasks.NpcProcessorTask;
+import lol.pyr.znpcsplus.tasks.ViewableHideOnLeaveListener;
 import lol.pyr.znpcsplus.updater.UpdateChecker;
 import lol.pyr.znpcsplus.updater.UpdateNotificationListener;
 import lol.pyr.znpcsplus.user.UserListener;
@@ -51,34 +51,36 @@ import net.kyori.adventure.platform.bukkit.BukkitAudiences;
 import net.kyori.adventure.text.Component;
 import net.kyori.adventure.text.format.NamedTextColor;
 import net.kyori.adventure.text.format.TextColor;
-import net.kyori.adventure.text.minimessage.MiniMessage;
 import net.kyori.adventure.text.serializer.legacy.LegacyComponentSerializer;
 import org.bstats.bukkit.Metrics;
 import org.bukkit.*;
 import org.bukkit.plugin.Plugin;
+import org.bukkit.plugin.PluginDescriptionFile;
 import org.bukkit.plugin.PluginManager;
-import org.bukkit.plugin.java.JavaPlugin;
 
 import java.io.File;
 import java.io.IOException;
 import java.io.PrintWriter;
-import java.io.Reader;
 import java.nio.file.Files;
 import java.nio.file.StandardOpenOption;
-import java.util.*;
+import java.util.ArrayList;
+import java.util.Collection;
+import java.util.HashMap;
+import java.util.List;
 
-public class ZNpcsPlus extends JavaPlugin {
+public class ZNpcsPlus {
     private final LegacyComponentSerializer textSerializer = LegacyComponentSerializer.builder()
             .character('&')
             .hexCharacter('#')
             .hexColors().build();
 
     private final List<Runnable> shutdownTasks = new ArrayList<>();
-    private PacketEventsAPI<Plugin> packetEvents;
+    private final PacketEventsAPI<Plugin> packetEvents;
+    private final ZNpcsPlusBootstrap bootstrap;
 
-    @Override
+    public ZNpcsPlus(ZNpcsPlusBootstrap bootstrap) {
-    public void onLoad() {
+        this.bootstrap = bootstrap;
-        packetEvents = SpigotPacketEventsBuilder.build(this);
+        packetEvents = SpigotPacketEventsBuilder.build(bootstrap);
         PacketEvents.setAPI(packetEvents);
         packetEvents.getSettings().checkForUpdates(false);
         packetEvents.load();
@@ -88,7 +90,6 @@ public class ZNpcsPlus extends JavaPlugin {
         Bukkit.getConsoleSender().sendMessage(str);
     }
 
-    @Override
     public void onEnable() {
         getDataFolder().mkdirs();
 
@@ -106,7 +107,7 @@ public class ZNpcsPlus extends JavaPlugin {
         } catch (IOException e) {
             log(ChatColor.RED + " * Moving legacy files to subfolder failed, plugin will shut down.");
             e.printStackTrace();
-            pluginManager.disablePlugin(this);
+            pluginManager.disablePlugin(bootstrap);
             return;
         }
 
@@ -114,12 +115,12 @@ public class ZNpcsPlus extends JavaPlugin {
 
         packetEvents.init();
 
-        BukkitAudiences adventure = BukkitAudiences.create(this);
+        BukkitAudiences adventure = BukkitAudiences.create(bootstrap);
         shutdownTasks.add(adventure::close);
 
         log(ChatColor.WHITE + " * Initializing components...");
 
-        TaskScheduler scheduler = FoliaUtil.isFolia() ? new FoliaScheduler(this) : new SpigotScheduler(this);
+        TaskScheduler scheduler = FoliaUtil.isFolia() ? new FoliaScheduler(bootstrap) : new SpigotScheduler(bootstrap);
         shutdownTasks.add(scheduler::cancelAll);
 
         ConfigManager configManager = new ConfigManager(getDataFolder());
@@ -137,7 +138,7 @@ public class ZNpcsPlus extends JavaPlugin {
         UserManager userManager = new UserManager();
         shutdownTasks.add(userManager::shutdown);
         
-        BungeeConnector bungeeConnector = new BungeeConnector(this);
+        BungeeConnector bungeeConnector = new BungeeConnector(bootstrap);
         DataImporterRegistry importerRegistry = new DataImporterRegistry(configManager, adventure,
                 scheduler, packetFactory, textSerializer, typeRegistry, getDataFolder().getParentFile(),
                 propertyRegistry, skinCache, npcRegistry, bungeeConnector);
@@ -150,23 +151,23 @@ public class ZNpcsPlus extends JavaPlugin {
         typeRegistry.registerDefault(packetEvents, propertyRegistry);
         actionRegistry.registerTypes(scheduler, adventure, textSerializer, bungeeConnector);
         packetEvents.getEventManager().registerListener(new InteractionPacketListener(userManager, npcRegistry, scheduler), PacketListenerPriority.MONITOR);
-        new Metrics(this, 18244);
+        new Metrics(bootstrap, 18244);
-        pluginManager.registerEvents(new UserListener(userManager), this);
+        pluginManager.registerEvents(new UserListener(userManager), bootstrap);
 
         registerCommands(npcRegistry, skinCache, adventure, actionRegistry,
                 typeRegistry, propertyRegistry, importerRegistry, configManager);
 
         log(ChatColor.WHITE + " * Starting tasks...");
         if (configManager.getConfig().checkForUpdates()) {
-            UpdateChecker updateChecker = new UpdateChecker(this.getDescription());
+            UpdateChecker updateChecker = new UpdateChecker(getDescription());
             scheduler.runDelayedTimerAsync(updateChecker, 5L, 6000L);
-            pluginManager.registerEvents(new UpdateNotificationListener(this, adventure, updateChecker), this);
+            pluginManager.registerEvents(new UpdateNotificationListener(this, adventure, updateChecker, scheduler), bootstrap);
         }
 
         scheduler.runDelayedTimerAsync(new NpcProcessorTask(npcRegistry, configManager, propertyRegistry), 60L, 3L);
         scheduler.runDelayedTimerAsync(new HologramRefreshTask(npcRegistry), 60L, 20L);
         scheduler.runDelayedTimerAsync(new SkinCacheCleanTask(skinCache), 1200, 1200);
-        pluginManager.registerEvents(new ViewableHideOnLeaveListener(), this);
+        pluginManager.registerEvents(new ViewableHideOnLeaveListener(), bootstrap);
 
         log(ChatColor.WHITE + " * Loading data...");
         npcRegistry.reload();
@@ -188,7 +189,7 @@ public class ZNpcsPlus extends JavaPlugin {
             }
         }
 
-        NpcApiProvider.register(this, new ZNpcsPlusApi(npcRegistry, typeRegistry, propertyRegistry, skinCache));
+        NpcApiProvider.register(bootstrap, new ZNpcsPlusApi(npcRegistry, typeRegistry, propertyRegistry, skinCache));
         log(ChatColor.WHITE + " * Loading complete! (" + (System.currentTimeMillis() - before) + "ms)");
         log("");
 
@@ -208,7 +209,6 @@ public class ZNpcsPlus extends JavaPlugin {
         }
     }
 
-    @Override
     public void onDisable() {
         NpcApiProvider.unregister();
         for (Runnable runnable : shutdownTasks) runnable.run();
@@ -238,7 +238,7 @@ public class ZNpcsPlus extends JavaPlugin {
                                   ConfigManager configManager) {
 
         Message<CommandContext> incorrectUsageMessage = context -> context.send(Component.text("Incorrect usage: /" + context.getUsage(), NamedTextColor.RED));
-        CommandManager manager = new CommandManager(this, adventure, incorrectUsageMessage);
+        CommandManager manager = new CommandManager(bootstrap, adventure, incorrectUsageMessage);
 
         manager.registerParser(NpcTypeImpl.class, new NpcTypeParser(incorrectUsageMessage, typeRegistry));
         manager.registerParser(NpcEntryImpl.class, new NpcEntryParser(npcRegistry, incorrectUsageMessage));
@@ -280,7 +280,7 @@ public class ZNpcsPlus extends JavaPlugin {
         registerEnumParser(manager, RabbitType.class, incorrectUsageMessage);
         registerEnumParser(manager, AttachDirection.class, incorrectUsageMessage);
 
-        manager.registerCommand("npc", new MultiCommand(loadHelpMessage("root"))
+        manager.registerCommand("npc", new MultiCommand(bootstrap.loadHelpMessage("root"))
                 .addSubcommand("center", new CenterCommand(npcRegistry))
                 .addSubcommand("create", new CreateCommand(npcRegistry, typeRegistry))
                 .addSubcommand("reloadconfig", new ReloadConfigCommand(configManager))
@@ -292,14 +292,14 @@ public class ZNpcsPlus extends JavaPlugin {
                 .addSubcommand("list", new ListCommand(npcRegistry))
                 .addSubcommand("near", new NearCommand(npcRegistry))
                 .addSubcommand("type", new TypeCommand(npcRegistry, typeRegistry))
-                .addSubcommand("property", new MultiCommand(loadHelpMessage("property"))
+                .addSubcommand("property", new MultiCommand(bootstrap.loadHelpMessage("property"))
                         .addSubcommand("set", new PropertySetCommand(npcRegistry))
                         .addSubcommand("remove", new PropertyRemoveCommand(npcRegistry)))
-                .addSubcommand("storage", new MultiCommand(loadHelpMessage("storage"))
+                .addSubcommand("storage", new MultiCommand(bootstrap.loadHelpMessage("storage"))
                         .addSubcommand("save", new SaveAllCommand(npcRegistry))
                         .addSubcommand("reload", new LoadAllCommand(npcRegistry))
                         .addSubcommand("import", new ImportCommand(npcRegistry, importerRegistry)))
-                .addSubcommand("holo", new MultiCommand(loadHelpMessage("holo"))
+                .addSubcommand("holo", new MultiCommand(bootstrap.loadHelpMessage("holo"))
                         .addSubcommand("add", new HoloAddCommand(npcRegistry))
                         .addSubcommand("additem", new HoloAddItemCommand(npcRegistry))
                         .addSubcommand("delete", new HoloDeleteCommand(npcRegistry))
@@ -310,7 +310,7 @@ public class ZNpcsPlus extends JavaPlugin {
                         .addSubcommand("setitem", new HoloSetItemCommand(npcRegistry))
                         .addSubcommand("offset", new HoloOffsetCommand(npcRegistry))
                         .addSubcommand("refreshdelay", new HoloRefreshDelayCommand(npcRegistry)))
-                .addSubcommand("action", new MultiCommand(loadHelpMessage("action"))
+                .addSubcommand("action", new MultiCommand(bootstrap.loadHelpMessage("action"))
                         .addSubcommand("add", new ActionAddCommand(npcRegistry, actionRegistry))
                         .addSubcommand("clear", new ActionClearCommand(npcRegistry))
                         .addSubcommand("delete", new ActionDeleteCommand(npcRegistry))
@@ -323,10 +323,11 @@ public class ZNpcsPlus extends JavaPlugin {
         manager.registerParser(clazz, new EnumParser<>(clazz, message));
     }
 
-    private Message<CommandContext> loadHelpMessage(String name) {
+    public File getDataFolder() {
-        Reader reader = getTextResource("help-messages/" + name + ".txt");
+        return bootstrap.getDataFolder();
-        if (reader == null) throw new RuntimeException(name + ".txt is missing from the help-messages folder in the ZNPCsPlus jar!");
+    }
-        Component component = MiniMessage.miniMessage().deserialize(FileUtil.dumpReaderAsString(reader));
+
-        return context -> context.send(component);
+    public PluginDescriptionFile getDescription() {
+        return bootstrap.getDescription();
     }
 }

plugin/src/main/java/lol/pyr/znpcsplus/ZNpcsPlusBootstrap.java

@@ -0,0 +1,90 @@
+package lol.pyr.znpcsplus;
+
+import lol.pyr.director.adventure.command.CommandContext;
+import lol.pyr.director.common.message.Message;
+import lol.pyr.znpcsplus.libraries.LibraryLoader;
+import lol.pyr.znpcsplus.util.FileUtil;
+import net.kyori.adventure.text.Component;
+import net.kyori.adventure.text.minimessage.MiniMessage;
+import org.bukkit.plugin.java.JavaPlugin;
+
+import java.io.File;
+import java.io.Reader;
+
+public class ZNpcsPlusBootstrap extends JavaPlugin {
+    private ZNpcsPlus zNpcsPlus;
+
+    @Override
+    public void onLoad() {
+        getLogger().info("Downloading and loading libraries, this might take a while if this is the first time you're launching the plugin");
+        LibraryLoader loader = new LibraryLoader(this, new File(getDataFolder(), "libraries"));
+
+        loader.addRelocation(decrypt("org..bstats"), "lol.pyr.znpcsplus.lib.bstats");
+        loader.addRelocation(decrypt("me..robertlit..spigotresources"), "lol.pyr.znpcsplus.lib.spigotresources");
+        loader.addRelocation(decrypt("net..kyori"), "lol.pyr.znpcsplus.lib.kyori");
+        loader.addRelocation(decrypt("org..checkerframework"), "lol.pyr.znpcsplus.lib.checkerframework");
+        loader.addRelocation(decrypt("com..google"), "lol.pyr.znpcsplus.lib.google");
+        loader.addRelocation(decrypt("com..github..retrooper..packetevents"), "lol.pyr.znpcsplus.lib.packetevents.api");
+        loader.addRelocation(decrypt("io..github..retrooper..packetevents"), "lol.pyr.znpcsplus.lib.packetevents.impl");
+        loader.addRelocation(decrypt("org..yaml..snakeyaml"), "lol.pyr.znpcsplus.lib.snakeyaml");
+        loader.addRelocation(decrypt("space..arim..dazzleconf"), "lol.pyr.znpcsplus.lib.dazzleconf");
+        loader.addRelocation(decrypt("lol..pyr..director"), "lol.pyr.znpcsplus.lib.command");
+        
+        loader.loadLibrary(decrypt("com..google..guava"), "guava", "18.0");
+        loader.loadLibrary(decrypt("com..google..code..gson"), "gson", "2.10.1");
+
+        loader.loadLibrary(decrypt("org..bstats"), "bstats-base", "3.0.2");
+        loader.loadLibrary(decrypt("org..bstats"), "bstats-bukkit", "3.0.2");
+
+        loader.loadLibrary("com.github.robertlit", "SpigotResourcesAPI", "2.0", "https://jitpack.io");
+
+        loader.loadSnapshotLibrary(decrypt("com..github..retrooper..packetevents"), "api", "2.1.0-SNAPSHOT", "2.1.0-20231011.171910-4", "https://repo.codemc.io/repository/maven-snapshots/");
+        loader.loadSnapshotLibrary(decrypt("com..github..retrooper..packetevents"), "spigot", "2.1.0-SNAPSHOT", "2.1.0-20231011.171910-4", "https://repo.codemc.io/repository/maven-snapshots/");
+
+        loader.loadLibrary(decrypt("space..arim..dazzleconf"), "dazzleconf-core", "1.2.1");
+        loader.loadLibrary(decrypt("space..arim..dazzleconf"), "dazzleconf-ext-snakeyaml", "1.2.1");
+        loader.loadLibrary("org.yaml", "snakeyaml", "1.33");
+
+        loader.loadLibrary("lol.pyr", "director-adventure", "2.1.1", "https://repo.pyr.lol/releases");
+
+        loader.loadLibrary(decrypt("net..kyori"), "adventure-api", "4.14.0");
+        loader.loadLibrary(decrypt("net..kyori"), "adventure-key", "4.14.0");
+        loader.loadLibrary(decrypt("net..kyori"), "adventure-nbt", "4.14.0");
+        loader.loadLibrary(decrypt("net..kyori"), "adventure-platform-facet", "4.3.1");
+        loader.loadLibrary(decrypt("net..kyori"), "adventure-platform-api", "4.3.1");
+        loader.loadLibrary(decrypt("net..kyori"), "adventure-platform-bukkit", "4.3.1");
+        loader.loadLibrary(decrypt("net..kyori"), "adventure-text-minimessage", "4.14.0");
+        loader.loadLibrary(decrypt("net..kyori"), "adventure-text-serializer-bungeecord", "4.3.1");
+        loader.loadLibrary(decrypt("net..kyori"), "adventure-text-serializer-gson", "4.14.0");
+        loader.loadLibrary(decrypt("net..kyori"), "adventure-text-serializer-json", "4.14.0");
+        loader.loadLibrary(decrypt("net..kyori"), "adventure-text-serializer-legacy", "4.14.0");
+        loader.loadLibrary(decrypt("net..kyori"), "examination-api", "1.3.0");
+        loader.loadLibrary(decrypt("net..kyori"), "examination-string", "1.3.0");
+        loader.deleteUnloadedLibraries();
+
+        getLogger().info("Loaded " + loader.loadedLibraryCount() + " libraries!");
+        zNpcsPlus = new ZNpcsPlus(this);
+    }
+
+    @Override
+    public void onEnable() {
+        if (zNpcsPlus != null) zNpcsPlus.onEnable();
+    }
+
+    @Override
+    public void onDisable() {
+        if (zNpcsPlus != null) zNpcsPlus.onDisable();
+    }
+
+    protected Message<CommandContext> loadHelpMessage(String name) {
+        Reader reader = getTextResource("help-messages/" + name + ".txt");
+        if (reader == null) throw new RuntimeException(name + ".txt is missing from the help-messages folder in the ZNPCsPlus jar!");
+        Component component = MiniMessage.miniMessage().deserialize(FileUtil.dumpReaderAsString(reader));
+        return context -> context.send(component);
+    }
+
+    // Ugly hack because of https://github.com/johnrengelman/shadow/issues/232
+    private static String decrypt(String packageName) {
+        return packageName.replace("..", ".");
+    }
+}

plugin/src/main/java/lol/pyr/znpcsplus/libraries/LibraryLoader.java

@@ -0,0 +1,119 @@
+package lol.pyr.znpcsplus.libraries;
+
+import me.lucko.jarrelocator.JarRelocator;
+import me.lucko.jarrelocator.Relocation;
+import org.bukkit.plugin.Plugin;
+
+import java.io.File;
+import java.io.IOException;
+import java.io.InputStream;
+import java.net.MalformedURLException;
+import java.net.URL;
+import java.net.URLClassLoader;
+import java.nio.file.Files;
+import java.util.ArrayList;
+import java.util.HashSet;
+import java.util.List;
+import java.util.Set;
+import java.util.logging.Logger;
+
+public class LibraryLoader {
+    private final static Logger logger = Logger.getLogger("ZNPCsPlus Library Loader");
+
+    private final UrlClassLoaderAccess loaderAccess;
+    private final File librariesFolder;
+    private final Set<File> loadedLibraries = new HashSet<>();
+    private final List<Relocation> relocationRules = new ArrayList<>();
+
+    public LibraryLoader(Plugin plugin, File librariesFolder) {
+        loaderAccess = UrlClassLoaderAccess.create((URLClassLoader) plugin.getClass().getClassLoader());
+        this.librariesFolder = librariesFolder;
+        if (!librariesFolder.exists()) librariesFolder.mkdirs();
+    }
+
+    public void deleteUnloadedLibraries() {
+        File[] files = librariesFolder.listFiles();
+        if (files == null) return;
+        for (File file : files) if (!loadedLibraries.contains(file)) file.delete();
+    }
+
+    public void addRelocation(String pre, String post) {
+        relocationRules.add(new Relocation(pre, post));
+    }
+
+    public void loadSnapshotLibrary(String groupId, String artifactId, String version, String snapshotVersion, String repoUrl) {
+        try {
+            loadLibrary(groupId + ":" + artifactId + ":" + version,
+                    getDependencyFile(groupId, artifactId, version),
+                    getSnapshotDependencyUrl(groupId, artifactId, version, snapshotVersion, repoUrl));
+        } catch (MalformedURLException e) {
+            throw new RuntimeException(e);
+        }
+    }
+
+    public int loadedLibraryCount() {
+        return loadedLibraries.size();
+    }
+
+    public void loadLibrary(String groupId, String artifactId, String version) {
+        loadLibrary(groupId, artifactId, version, "https://repo1.maven.org/maven2");
+    }
+
+    public void loadLibrary(String groupId, String artifactId, String version, String repoUrl) {
+        try {
+            loadLibrary(groupId + ":" + artifactId + ":" + version,
+                    getDependencyFile(groupId, artifactId, version),
+                    getDependencyUrl(groupId, artifactId, version, repoUrl));
+        } catch (MalformedURLException e) {
+            throw new RuntimeException(e);
+        }
+    }
+
+    private void loadLibrary(String name, File file, URL url) {
+        if (!file.exists()) {
+            try (InputStream in = url.openStream()) {
+                File temp = new File(file.getParentFile(), file.getName() + ".temp");
+                Files.copy(in, temp.toPath());
+                new JarRelocator(temp, file, relocationRules).run();
+                temp.delete();
+                // logger.info("Downloaded library " + name);
+            } catch (IOException e) {
+                logger.severe("Failed to download library " + name);
+                e.printStackTrace();
+            }
+        }
+
+        try {
+            loaderAccess.addURL(file.toURI().toURL());
+            loadedLibraries.add(file);
+            // logger.info("Loaded library " + name);
+        } catch (Exception e) {
+            logger.severe("Failed to load library, plugin may not work correctly (" + name + ")");
+            e.printStackTrace();
+        }
+    }
+
+    private File getDependencyFile(String groupId, String artifactId, String version) {
+        return new File(librariesFolder, groupId.replace(".", "-") + "-"
+                + artifactId.replace(".", "-") + "-"
+                + version.replace(".", "-") + ".jar");
+    }
+
+    private static URL getDependencyUrl(String groupId, String artifactId, String version, String repoUrl) throws MalformedURLException {
+        String url = repoUrl.endsWith("/") ? repoUrl : repoUrl + "/";
+        url += groupId.replace(".", "/") + "/";
+        url += artifactId + "/";
+        url += version + "/";
+        url += artifactId + "-" + version + ".jar";
+        return new URL(url);
+    }
+
+    private static URL getSnapshotDependencyUrl(String groupId, String artifactId, String version, String snapshotVersion, String repoUrl) throws MalformedURLException {
+        String url = repoUrl.endsWith("/") ? repoUrl : repoUrl + "/";
+        url += groupId.replace(".", "/") + "/";
+        url += artifactId + "/";
+        url += version + "/";
+        url += artifactId + "-" + snapshotVersion + ".jar";
+        return new URL(url);
+    }
+}

plugin/src/main/java/lol/pyr/znpcsplus/libraries/UrlClassLoaderAccess.java

@@ -0,0 +1,152 @@
+package lol.pyr.znpcsplus.libraries;
+
+import javax.annotation.Nonnull;
+import java.lang.reflect.Field;
+import java.lang.reflect.Method;
+import java.net.URL;
+import java.net.URLClassLoader;
+import java.util.Collection;
+
+/**
+ * Provides access to {@link URLClassLoader}#addURL.
+ * From https://github.com/lucko/helper/blob/master/helper/src/main/java/me/lucko/helper/maven/URLClassLoaderAccess.java
+ */
+public abstract class UrlClassLoaderAccess {
+
+    /**
+     * Creates a {@link UrlClassLoaderAccess} for the given class loader.
+     *
+     * @param classLoader the class loader
+     * @return the access object
+     */
+    static UrlClassLoaderAccess create(URLClassLoader classLoader) {
+        if (Reflection.isSupported()) {
+            return new Reflection(classLoader);
+        } else if (Unsafe.isSupported()) {
+            return new Unsafe(classLoader);
+        } else {
+            return Noop.INSTANCE;
+        }
+    }
+
+    private final URLClassLoader classLoader;
+
+    protected UrlClassLoaderAccess(URLClassLoader classLoader) {
+        this.classLoader = classLoader;
+    }
+
+
+    /**
+     * Adds the given URL to the class loader.
+     *
+     * @param url the URL to add
+     */
+    public abstract void addURL(@Nonnull URL url);
+
+    /**
+     * Accesses using reflection, not supported on Java 9+.
+     */
+    private static class Reflection extends UrlClassLoaderAccess {
+        private static final Method ADD_URL_METHOD;
+
+        static {
+            Method addUrlMethod;
+            try {
+                addUrlMethod = URLClassLoader.class.getDeclaredMethod("addURL", URL.class);
+                addUrlMethod.setAccessible(true);
+            } catch (Exception e) {
+                addUrlMethod = null;
+            }
+            ADD_URL_METHOD = addUrlMethod;
+        }
+
+        private static boolean isSupported() {
+            return ADD_URL_METHOD != null;
+        }
+
+        Reflection(URLClassLoader classLoader) {
+            super(classLoader);
+        }
+
+        @Override
+        public void addURL(@Nonnull URL url) {
+            try {
+                ADD_URL_METHOD.invoke(super.classLoader, url);
+            } catch (ReflectiveOperationException e) {
+                throw new RuntimeException(e);
+            }
+        }
+    }
+
+    /**
+     * Accesses using sun.misc.Unsafe, supported on Java 9+.
+     *
+     * @author Vaishnav Anil (https://github.com/slimjar/slimjar)
+     */
+    private static class Unsafe extends UrlClassLoaderAccess {
+        private static final sun.misc.Unsafe UNSAFE;
+
+        static {
+            sun.misc.Unsafe unsafe;
+            try {
+                Field unsafeField = sun.misc.Unsafe.class.getDeclaredField("theUnsafe");
+                unsafeField.setAccessible(true);
+                unsafe = (sun.misc.Unsafe) unsafeField.get(null);
+            } catch (Throwable t) {
+                unsafe = null;
+            }
+            UNSAFE = unsafe;
+        }
+
+        private static boolean isSupported() {
+            return UNSAFE != null;
+        }
+
+        private final Collection<URL> unopenedURLs;
+        private final Collection<URL> pathURLs;
+
+        @SuppressWarnings("unchecked")
+        Unsafe(URLClassLoader classLoader) {
+            super(classLoader);
+
+            Collection<URL> unopenedURLs;
+            Collection<URL> pathURLs;
+            try {
+                Object ucp = fetchField(URLClassLoader.class, classLoader, "ucp");
+                unopenedURLs = (Collection<URL>) fetchField(ucp.getClass(), ucp, "unopenedUrls");
+                pathURLs = (Collection<URL>) fetchField(ucp.getClass(), ucp, "path");
+            } catch (Throwable e) {
+                unopenedURLs = null;
+                pathURLs = null;
+            }
+            this.unopenedURLs = unopenedURLs;
+            this.pathURLs = pathURLs;
+        }
+
+        private static Object fetchField(final Class<?> clazz, final Object object, final String name) throws NoSuchFieldException {
+            Field field = clazz.getDeclaredField(name);
+            long offset = UNSAFE.objectFieldOffset(field);
+            return UNSAFE.getObject(object, offset);
+        }
+
+        @Override
+        public void addURL(@Nonnull URL url) {
+            this.unopenedURLs.add(url);
+            this.pathURLs.add(url);
+        }
+    }
+
+    private static class Noop extends UrlClassLoaderAccess {
+        private static final Noop INSTANCE = new Noop();
+
+        private Noop() {
+            super(null);
+        }
+
+        @Override
+        public void addURL(@Nonnull URL url) {
+            throw new UnsupportedOperationException();
+        }
+    }
+
+}

plugin/src/main/java/lol/pyr/znpcsplus/updater/UpdateNotificationListener.java

@@ -1,11 +1,11 @@
 package lol.pyr.znpcsplus.updater;
 
 import lol.pyr.znpcsplus.ZNpcsPlus;
+import lol.pyr.znpcsplus.scheduling.TaskScheduler;
 import net.kyori.adventure.platform.bukkit.BukkitAudiences;
 import net.kyori.adventure.text.Component;
 import net.kyori.adventure.text.event.ClickEvent;
 import net.kyori.adventure.text.format.NamedTextColor;
-import org.bukkit.Bukkit;
 import org.bukkit.event.EventHandler;
 import org.bukkit.event.Listener;
 import org.bukkit.event.player.PlayerJoinEvent;
@@ -14,18 +14,20 @@ public class UpdateNotificationListener implements Listener {
     private final ZNpcsPlus plugin;
     private final BukkitAudiences adventure;
     private final UpdateChecker updateChecker;
+    private final TaskScheduler scheduler;
 
-    public UpdateNotificationListener(ZNpcsPlus plugin, BukkitAudiences adventure, UpdateChecker updateChecker) {
+    public UpdateNotificationListener(ZNpcsPlus plugin, BukkitAudiences adventure, UpdateChecker updateChecker, TaskScheduler scheduler) {
         this.plugin = plugin;
         this.adventure = adventure;
         this.updateChecker = updateChecker;
+        this.scheduler = scheduler;
     }
 
     @EventHandler
     public void onJoin(PlayerJoinEvent event) {
         if (!event.getPlayer().hasPermission("znpcsplus.updates")) return;
         if (updateChecker.getStatus() != UpdateChecker.Status.UPDATE_NEEDED) return;
-        Bukkit.getScheduler().runTaskLater(plugin, () -> {
+        scheduler.runLaterAsync(() -> {
             if (!event.getPlayer().isOnline()) return;
             adventure.player(event.getPlayer())
                     .sendMessage(Component.text(plugin.getDescription().getName() + " v" + updateChecker.getLatestVersion() + " is available now!", NamedTextColor.GOLD).appendNewline()

plugin/src/main/resources/plugin.yml

@@ -3,7 +3,7 @@ authors:
   - Pyr
   - D3v1s0m
 
-main: lol.pyr.znpcsplus.ZNpcsPlus
+main: lol.pyr.znpcsplus.ZNpcsPlusBootstrap
 load: POSTWORLD
 
 version: ${version}