Migrate SLF4J logging (Fixes #177)

.travis.yml

@@ -6,6 +6,8 @@ sudo: false
 # This is a java project
 language: java
 
-script: mvn compile test
+script: mvn test -B
 
-jdk: [oraclejdk8]
+jdk:
+  - oraclejdk8
+  - oraclejdk9

README.md

@@ -38,7 +38,7 @@ So they don't need to enter passwords. This is also called auto login (auto-logi
 
 ### Requirements:
 * Plugin: [ProtocolLib](https://www.spigotmc.org/resources/protocollib.1997/) or [ProtocolSupport](https://www.spigotmc.org/resources/protocolsupport.7201/)
-* Tested [Spigot](https://www.spigotmc.org) 1.8+ (could also work with other versions)
+* [Spigot](https://www.spigotmc.org) 1.7+
 * Java 8+
 * Run Spigot and/or BungeeCord/Waterfall in offline mode (see server.properties or config.yml)
 * An auth plugin. Supported plugins

bukkit/src/main/java/com/github/games647/fastlogin/bukkit/FastLoginBukkit.java

@@ -27,6 +27,7 @@ import org.bukkit.command.CommandSender;
 import org.bukkit.entity.Player;
 import org.bukkit.plugin.java.JavaPlugin;
 import org.bukkit.plugin.messaging.PluginMessageRecipient;
+import org.slf4j.Logger;
 
 /**
  * This plugin checks if a player has a paid account and if so tries to skip offline mode authentication.
@@ -35,6 +36,7 @@ public class FastLoginBukkit extends JavaPlugin implements PlatformPlugin<Comman
 
     //provide a immutable key pair to be thread safe | used for encrypting and decrypting traffic
     private final KeyPair keyPair = EncryptionUtil.generateKeyPair();
+    private final Logger logger = CommonUtil.createLoggerFromJDK(getLogger());
 
     private boolean bungeeCord;
     private FastLoginCore<Player, CommandSender, FastLoginBukkit> core;
@@ -52,12 +54,12 @@ public class FastLoginBukkit extends JavaPlugin implements PlatformPlugin<Comman
         } catch (ClassNotFoundException notFoundEx) {
             //ignore server has no bungee support
         } catch (Exception ex) {
-            getLogger().log(Level.WARNING, "Cannot check bungeecord support. You use a non-spigot build", ex);
+            logger.warn("Cannot check bungeecord support. You use a non-spigot build", ex);
         }
 
         if (getServer().getOnlineMode()) {
             //we need to require offline to prevent a loginSession request for a offline player
-            getLogger().severe("Server have to be in offline mode");
+            logger.error("Server have to be in offline mode");
             setEnabled(false);
             return;
         }
@@ -85,8 +87,7 @@ public class FastLoginBukkit extends JavaPlugin implements PlatformPlugin<Comman
 
                 getServer().getPluginManager().registerEvents(new LoginSkinApplyListener(this), this);
             } else {
-                getLogger().warning("Either ProtocolLib or ProtocolSupport have to be installed "
+                logger.warn("Either ProtocolLib or ProtocolSupport have to be installed if you don't use BungeeCord");
-                        + "if you don't use BungeeCord");
             }
         }
 
@@ -127,7 +128,7 @@ public class FastLoginBukkit extends JavaPlugin implements PlatformPlugin<Comman
         } else {
             Player firstPlayer = Iterables.getFirst(getServer().getOnlinePlayers(), null);
             if (firstPlayer == null) {
-                getLogger().info("No player online to send a plugin message to the proxy");
+                logger.info("No player online to send a plugin message to the proxy");
                 return;
             }
 
@@ -187,6 +188,11 @@ public class FastLoginBukkit extends JavaPlugin implements PlatformPlugin<Comman
         sender.sendPluginMessage(this, getName(), dataOutput.toByteArray());
     }
 
+    @Override
+    public Logger getLog() {
+        return logger;
+    }
+
     @Override
     public void sendMessage(CommandSender receiver, String message) {
         receiver.sendMessage(message);
@@ -200,6 +206,6 @@ public class FastLoginBukkit extends JavaPlugin implements PlatformPlugin<Comman
 
     @Override
     public MojangApiConnector makeApiConnector(List<String> addresses, int requests, List<HostAndPort> proxies) {
-        return new MojangApiBukkit(getLogger(), addresses, requests, proxies);
+        return new MojangApiBukkit(getLog(), addresses, requests, proxies);
     }
 }

bukkit/src/main/java/com/github/games647/fastlogin/bukkit/MojangApiBukkit.java

@@ -13,14 +13,14 @@ import java.net.InetSocketAddress;
 import java.net.URLEncoder;
 import java.util.Collection;
 import java.util.List;
-import java.util.logging.Level;
+
-import java.util.logging.Logger;
+import org.slf4j.Logger;
 
 public class MojangApiBukkit extends MojangApiConnector {
 
     //mojang api check to prove a player is logged in minecraft and made a join server request
     private static final String HAS_JOINED_URL = "https://sessionserver.mojang.com/session/minecraft/hasJoined?" +
-            "username=%s&serverId=%s";
+            "username=%s&serverId=%s&ip=%s";
 
     public MojangApiBukkit(Logger logger, Collection<String> localAddresses, int rateLimit
             , List<HostAndPort> proxies) {
@@ -31,11 +31,9 @@ public class MojangApiBukkit extends MojangApiConnector {
     public boolean hasJoinedServer(LoginSession session, String serverId, InetSocketAddress ip) {
         BukkitLoginSession playerSession = (BukkitLoginSession) session;
 
-        String url = String.format(HAS_JOINED_URL, playerSession.getUsername(), serverId);
         try {
-            if (ip != null) {
+            String encodedIp = URLEncoder.encode(ip.getAddress().getHostAddress(), "UTF-8");
-                url += "&ip=" + URLEncoder.encode(ip.getAddress().getHostAddress(), "UTF-8");
+            String url = String.format(HAS_JOINED_URL, playerSession.getUsername(), serverId, encodedIp);
-            }
 
             HttpURLConnection conn = getConnection(url);
 
@@ -55,7 +53,7 @@ public class MojangApiBukkit extends MojangApiConnector {
             }
         } catch (Exception ex) {
             //catch not only io-exceptions also parse and NPE on unexpected json format
-            logger.log(Level.WARNING, "Failed to verify session", ex);
+            logger.warn("Failed to verify session", ex);
         }
 
         //this connection doesn't need to be closed. So can make use of keep alive in java

bukkit/src/main/java/com/github/games647/fastlogin/bukkit/listener/BungeeListener.java

@@ -14,7 +14,6 @@ import java.nio.file.Path;
 import java.util.Collections;
 import java.util.Set;
 import java.util.UUID;
-import java.util.logging.Level;
 import java.util.stream.Collectors;
 
 import org.bukkit.Bukkit;
@@ -48,20 +47,19 @@ public class BungeeListener implements PluginMessageListener {
 
         ByteArrayDataInput dataInput = ByteStreams.newDataInput(message);
         String subChannel = dataInput.readUTF();
-        plugin.getLogger().log(Level.FINEST, "Received plugin message for sub channel {0} from {1}"
+        plugin.getLog().debug("Received plugin message for sub channel {} from {}", subChannel, player);
-                , new Object[]{subChannel, player});
 
         String playerName = dataInput.readUTF();
 
         //check if the player is still online or disconnected
-        Player checkedPlayer = plugin.getServer().getPlayerExact(playerName);
+        Player checkedPlayer = Bukkit.getPlayerExact(playerName);
         //fail if target player is blacklisted because already authenticated or wrong bungeecord id
         if (checkedPlayer != null && !checkedPlayer.hasMetadata(plugin.getName())) {
             //bungeecord UUID
             long mostSignificantBits = dataInput.readLong();
             long leastSignificantBits = dataInput.readLong();
             UUID sourceId = new UUID(mostSignificantBits, leastSignificantBits);
-            plugin.getLogger().log(Level.FINEST, "Received proxy id {0} from {1}", new Object[]{sourceId, player});
+            plugin.getLog().debug("Received proxy id {} from {}", sourceId, player);
 
             //fail if BungeeCord support is disabled (id = null)
             if (proxyIds.contains(sourceId)) {
@@ -90,7 +88,7 @@ public class BungeeListener implements PluginMessageListener {
                         new ForceLoginTask(plugin.getCore(), player).run();
                     }
                 } catch (Exception ex) {
-                    plugin.getLogger().log(Level.SEVERE, "Failed to query isRegistered", ex);
+                    plugin.getLog().error("Failed to query isRegistered", ex);
                 }
             });
         }
@@ -108,9 +106,9 @@ public class BungeeListener implements PluginMessageListener {
                     .map(UUID::fromString)
                     .collect(Collectors.toSet());
         } catch (IOException ex) {
-            plugin.getLogger().log(Level.SEVERE, "Failed to create file for Proxy whitelist", ex);
+            plugin.getLog().error("Failed to create file for Proxy whitelist", ex);
         } catch (Exception ex) {
-            plugin.getLogger().log(Level.SEVERE, "Failed to retrieve proxy Id. Disabling BungeeCord support", ex);
+            plugin.getLog().error("Failed to retrieve proxy Id. Disabling BungeeCord support", ex);
         }
 
         return Collections.emptySet();

bukkit/src/main/java/com/github/games647/fastlogin/bukkit/listener/protocollib/LoginSkinApplyListener.java

@@ -11,7 +11,6 @@ import com.github.games647.fastlogin.bukkit.FastLoginBukkit;
 import com.github.games647.fastlogin.core.mojang.SkinProperties;
 
 import java.lang.reflect.InvocationTargetException;
-import java.util.logging.Level;
 
 import org.bukkit.entity.Player;
 import org.bukkit.event.EventHandler;
@@ -65,7 +64,7 @@ public class LoginSkinApplyListener implements Listener {
                 try {
                     MethodUtils.invokeMethod(map, "put", new Object[]{"textures", skin.getHandle()});
                 } catch (NoSuchMethodException | IllegalAccessException | InvocationTargetException ex) {
-                    plugin.getLogger().log(Level.SEVERE, "Error setting premium skin", ex);
+                    plugin.getLog().error("Error setting premium skin", ex);
                 }
             }
         }

bukkit/src/main/java/com/github/games647/fastlogin/bukkit/listener/protocollib/NameCheckTask.java

@@ -8,7 +8,6 @@ import com.github.games647.fastlogin.core.PlayerProfile;
 import com.github.games647.fastlogin.core.shared.JoinManagement;
 
 import java.util.Random;
-import java.util.logging.Level;
 
 import org.bukkit.command.CommandSender;
 import org.bukkit.entity.Player;
@@ -50,7 +49,7 @@ public class NameCheckTask extends JoinManagement<Player, CommandSender, Protoco
         try {
             source.setOnlineMode();
         } catch (Exception ex) {
-            plugin.getLogger().log(Level.SEVERE, "Cannot send encryption packet. Falling back to cracked login", ex);
+            plugin.getLog().error("Cannot send encryption packet. Falling back to cracked login", ex);
             return;
         }
 

bukkit/src/main/java/com/github/games647/fastlogin/bukkit/listener/protocollib/ProtocolLibListener.java

@@ -8,7 +8,6 @@ import com.comphenix.protocol.events.PacketEvent;
 import com.github.games647.fastlogin.bukkit.FastLoginBukkit;
 
 import java.security.SecureRandom;
-import java.util.logging.Level;
 
 import org.bukkit.Bukkit;
 import org.bukkit.entity.Player;
@@ -77,7 +76,7 @@ public class ProtocolLibListener extends PacketAdapter {
         PacketContainer packet = packetEvent.getPacket();
 
         String username = packet.getGameProfiles().read(0).getName();
-        plugin.getLogger().log(Level.FINER, "GameProfile {0} with {1} connecting", new Object[]{sessionKey, username});
+        plugin.getLog().trace("GameProfile {} with {} connecting", sessionKey, username);
 
         packetEvent.getAsyncMarker().incrementProcessingDelay();
         Runnable nameCheckTask = new NameCheckTask(plugin, packetEvent, random, player, username);

bukkit/src/main/java/com/github/games647/fastlogin/bukkit/listener/protocollib/VerifyResponseTask.java

@@ -20,7 +20,6 @@ import java.security.PrivateKey;
 import java.security.PublicKey;
 import java.util.Arrays;
 import java.util.UUID;
-import java.util.logging.Level;
 
 import javax.crypto.Cipher;
 import javax.crypto.SecretKey;
@@ -97,7 +96,7 @@ public class VerifyResponseTask implements Runnable {
 
         String username = session.getUsername();
         if (plugin.getCore().getApiConnector().hasJoinedServer(session, serverId, player.getAddress())) {
-            plugin.getLogger().log(Level.INFO, "GameProfile {0} has a verified premium account", username);
+            plugin.getLog().info("GameProfile {} has a verified premium account", username);
 
             session.setVerified(true);
             setPremiumUUID(session.getUuid());
@@ -117,7 +116,7 @@ public class VerifyResponseTask implements Runnable {
                 //https://github.com/bergerkiller/CraftSource/blob/master/net.minecraft.server/NetworkManager.java#L69
                 FieldUtils.writeField(networkManager, "spoofedUUID", premiumUUID, true);
             } catch (Exception exc) {
-                plugin.getLogger().log(Level.SEVERE, "Error setting premium uuid", exc);
+                plugin.getLog().error("Error setting premium uuid", exc);
             }
         }
     }
@@ -172,9 +171,9 @@ public class VerifyResponseTask implements Runnable {
 
     private void disconnect(String kickReason, boolean debug, String logMessage, Object... arguments) {
         if (debug) {
-            plugin.getLogger().log(Level.FINE, logMessage, arguments);
+            plugin.getLog().debug(logMessage, arguments);
         } else {
-            plugin.getLogger().log(Level.SEVERE, logMessage, arguments);
+            plugin.getLog().error(logMessage, arguments);
         }
 
         kickPlayer(plugin.getCore().getMessage(kickReason));
@@ -192,7 +191,7 @@ public class VerifyResponseTask implements Runnable {
             //tell the server that we want to close the connection
             player.kickPlayer("Disconnect");
         } catch (InvocationTargetException ex) {
-            plugin.getLogger().log(Level.SEVERE, "Error sending kick packet", ex);
+            plugin.getLog().error("Error sending kick packet", ex);
         }
     }
 
@@ -210,7 +209,7 @@ public class VerifyResponseTask implements Runnable {
             //we don't want to handle our own packets so ignore filters
             protocolManager.recieveClientPacket(player, startPacket, false);
         } catch (InvocationTargetException | IllegalAccessException ex) {
-            plugin.getLogger().log(Level.WARNING, "Failed to fake a new start packet", ex);
+            plugin.getLog().warn("Failed to fake a new start packet", ex);
             //cancel the event in order to prevent the server receiving an invalid packet
             kickPlayer(plugin.getCore().getMessage("error-kick"));
         }

bukkit/src/main/java/com/github/games647/fastlogin/bukkit/tasks/DelayedAuthHook.java

@@ -11,7 +11,6 @@ import com.github.games647.fastlogin.core.hooks.AuthPlugin;
 import com.google.common.collect.Lists;
 
 import java.util.List;
-import java.util.logging.Level;
 
 import org.bukkit.Bukkit;
 import org.bukkit.entity.Player;
@@ -28,9 +27,9 @@ public class DelayedAuthHook implements Runnable {
     public void run() {
         boolean hookFound = plugin.getCore().getAuthPluginHook() != null || registerHooks();
         if (plugin.isBungeeCord()) {
-            plugin.getLogger().info("BungeeCord setting detected. No auth plugin is required");
+            plugin.getLog().info("BungeeCord setting detected. No auth plugin is required");
         } else if (!hookFound) {
-            plugin.getLogger().warning("No auth plugin were found by this plugin "
+            plugin.getLog().warn("No auth plugin were found by this plugin "
                     + "(other plugins could hook into this after the initialization of this plugin)"
                     + "and BungeeCord is deactivated. "
                     + "Either one or both of the checks have to pass in order to use this plugin");
@@ -53,20 +52,20 @@ public class DelayedAuthHook implements Runnable {
             for (Class<? extends AuthPlugin<Player>> clazz : supportedHooks) {
                 String pluginName = clazz.getSimpleName().replace("Hook", "");
                 //uses only member classes which uses AuthPlugin interface (skip interfaces)
-                if (Bukkit.getServer().getPluginManager().isPluginEnabled(pluginName)) {
+                if (Bukkit.getPluginManager().isPluginEnabled(pluginName)) {
                     //check only for enabled plugins. A single plugin could be disabled by plugin managers
                     authPluginHook = clazz.newInstance();
-                    plugin.getLogger().log(Level.INFO, "Hooking into auth plugin: {0}", pluginName);
+                    plugin.getLog().info("Hooking into auth plugin: {}", pluginName);
                     break;
                 }
             }
         } catch (InstantiationException | IllegalAccessException ex) {
-            plugin.getLogger().log(Level.SEVERE, "Couldn't load the integration class", ex);
+            plugin.getLog().error("Couldn't load the integration class", ex);
         }
 
         if (authPluginHook == null) {
             //run this check for exceptions (errors) and not found plugins
-            plugin.getLogger().warning("No support offline Auth plugin found. ");
+            plugin.getLog().warn("No support offline Auth plugin found. ");
             return false;
         }
 

bukkit/src/main/java/com/github/games647/fastlogin/bukkit/tasks/ForceLoginTask.java

@@ -9,7 +9,6 @@ import com.google.common.io.ByteArrayDataOutput;
 import com.google.common.io.ByteStreams;
 
 import java.util.concurrent.ExecutionException;
-import java.util.logging.Level;
 
 import org.bukkit.Bukkit;
 import org.bukkit.command.CommandSender;
@@ -56,7 +55,7 @@ public class ForceLoginTask extends ForceLoginManagement<Player, CommandSender,
             //the player-list isn't thread-safe
             return Bukkit.getScheduler().callSyncMethod(core.getPlugin(), player::isOnline).get();
         } catch (InterruptedException | ExecutionException ex) {
-            core.getPlugin().getLogger().log(Level.SEVERE, "Failed to perform thread-safe online check", ex);
+            core.getPlugin().getLog().error("Failed to perform thread-safe online check", ex);
             return false;
         }
     }

bungee/src/main/java/com/github/games647/fastlogin/bungee/FastLoginBungee.java

@@ -3,6 +3,7 @@ package com.github.games647.fastlogin.bungee;
 import com.github.games647.fastlogin.bungee.hooks.BungeeAuthHook;
 import com.github.games647.fastlogin.bungee.listener.ConnectListener;
 import com.github.games647.fastlogin.bungee.listener.MessageListener;
+import com.github.games647.fastlogin.core.CommonUtil;
 import com.github.games647.fastlogin.core.mojang.MojangApiConnector;
 import com.github.games647.fastlogin.core.shared.FastLoginCore;
 import com.github.games647.fastlogin.core.shared.PlatformPlugin;
@@ -20,12 +21,15 @@ import net.md_5.bungee.api.connection.ProxiedPlayer;
 import net.md_5.bungee.api.plugin.Plugin;
 import net.md_5.bungee.api.scheduler.GroupedThreadFactory;
 
+import org.slf4j.Logger;
+
 /**
  * BungeeCord version of FastLogin. This plugin keeps track on online mode connections.
  */
 public class FastLoginBungee extends Plugin implements PlatformPlugin<CommandSender> {
 
     private final ConcurrentMap<PendingConnection, BungeeLoginSession> session = Maps.newConcurrentMap();
+    private final Logger logger = CommonUtil.createLoggerFromJDK(getLogger());
 
     private FastLoginCore<ProxiedPlayer, CommandSender, FastLoginBungee> core;
 
@@ -66,7 +70,7 @@ public class FastLoginBungee extends Plugin implements PlatformPlugin<CommandSen
         Plugin plugin = getProxy().getPluginManager().getPlugin("BungeeAuth");
         if (plugin != null) {
             core.setAuthPluginHook(new BungeeAuthHook());
-            getLogger().info("Hooked into BungeeAuth");
+            logger.info("Hooked into BungeeAuth");
         }
     }
 
@@ -75,6 +79,11 @@ public class FastLoginBungee extends Plugin implements PlatformPlugin<CommandSen
         return getDescription().getName();
     }
 
+    @Override
+    public Logger getLog() {
+        return logger;
+    }
+
     @Override
     public void sendMessage(CommandSender receiver, String message) {
         receiver.sendMessage(TextComponent.fromLegacyText(message));
@@ -88,6 +97,6 @@ public class FastLoginBungee extends Plugin implements PlatformPlugin<CommandSen
 
     @Override
     public MojangApiConnector makeApiConnector(List<String> addresses, int requests, List<HostAndPort> proxies) {
-        return new MojangApiConnector(getLogger(), addresses, requests, proxies);
+        return new MojangApiConnector(getLog(), addresses, requests, proxies);
     }
 }

bungee/src/main/java/com/github/games647/fastlogin/bungee/listener/ConnectListener.java

@@ -9,7 +9,6 @@ import com.google.common.base.Charsets;
 
 import java.lang.reflect.Field;
 import java.util.UUID;
-import java.util.logging.Level;
 
 import net.md_5.bungee.api.ProxyServer;
 import net.md_5.bungee.api.connection.PendingConnection;
@@ -82,7 +81,7 @@ public class ConnectListener implements Listener {
                     idField.setAccessible(true);
                     idField.set(connection, offlineUUID);
                 } catch (NoSuchFieldException | IllegalAccessException ex) {
-                    plugin.getLogger().log(Level.SEVERE, "Failed to set offline uuid", ex);
+                    plugin.getLog().error("Failed to set offline uuid", ex);
                 }
             }
 

core/src/main/java/com/github/games647/fastlogin/core/AuthStorage.java

@@ -13,7 +13,6 @@ import java.sql.Statement;
 import java.util.Properties;
 import java.util.UUID;
 import java.util.concurrent.ThreadFactory;
-import java.util.logging.Level;
 
 public class AuthStorage {
 
@@ -104,7 +103,7 @@ public class AuthStorage {
                 }
             }
         } catch (SQLException sqlEx) {
-            core.getPlugin().getLogger().log(Level.SEVERE, "Failed to query profile", sqlEx);
+            core.getPlugin().getLog().error("Failed to query profile", sqlEx);
         }
 
         return null;
@@ -128,7 +127,7 @@ public class AuthStorage {
                 }
             }
         } catch (SQLException sqlEx) {
-            core.getPlugin().getLogger().log(Level.SEVERE, "Failed to query profile", sqlEx);
+            core.getPlugin().getLog().error("Failed to query profile", sqlEx);
         }
 
         return null;
@@ -179,7 +178,7 @@ public class AuthStorage {
 
             return true;
         } catch (SQLException ex) {
-            core.getPlugin().getLogger().log(Level.SEVERE, "Failed to save playerProfile", ex);
+            core.getPlugin().getLog().error("Failed to save playerProfile", ex);
         }
 
         return false;

core/src/main/java/com/github/games647/fastlogin/core/CommonUtil.java

@@ -2,9 +2,15 @@ package com.github.games647.fastlogin.core;
 
 import com.google.common.cache.CacheLoader;
 
+import java.lang.reflect.Constructor;
 import java.util.UUID;
 import java.util.concurrent.ConcurrentMap;
 import java.util.concurrent.TimeUnit;
+import java.util.logging.Level;
+
+import org.slf4j.Logger;
+import org.slf4j.LoggerFactory;
+import org.slf4j.impl.JDK14LoggerAdapter;
 
 public class CommonUtil {
 
@@ -47,6 +53,19 @@ public class CommonUtil {
         return new String(chars);
     }
 
+    public static Logger createLoggerFromJDK(java.util.logging.Logger parent) {
+        try {
+            Class<JDK14LoggerAdapter> adapterClass = JDK14LoggerAdapter.class;
+            Constructor<JDK14LoggerAdapter> cons = adapterClass.getDeclaredConstructor(java.util.logging.Logger.class);
+            cons.setAccessible(true);
+            return cons.newInstance(parent);
+        } catch (ReflectiveOperationException reflectEx) {
+            parent.log(Level.WARNING, "Cannot create slf4j logging adapter", reflectEx);
+            parent.log(Level.WARNING, "Creating logger instance manually...");
+            return LoggerFactory.getLogger(parent.getName());
+        }
+    }
+
     private CommonUtil() {
         //Utility class
     }

core/src/main/java/com/github/games647/fastlogin/core/mojang/MojangApiConnector.java

@@ -27,24 +27,23 @@ import java.util.Map;
 import java.util.Optional;
 import java.util.Set;
 import java.util.UUID;
-import java.util.logging.Level;
-import java.util.logging.Logger;
 import java.util.regex.Pattern;
 
 import javax.net.ssl.HttpsURLConnection;
 import javax.net.ssl.SSLSocketFactory;
 
+import org.slf4j.Logger;
+
 public class MojangApiConnector {
 
     //http connection, read timeout and user agent for a connection to mojang api servers
     private static final int TIMEOUT = 3 * 1_000;
     private static final String USER_AGENT = "Premium-Checker";
+    private static final int RATE_LIMIT_CODE = 429;
 
     //only premium (paid account) users have a uuid from here
     private static final String UUID_LINK = "https://api.mojang.com/users/profiles/minecraft/";
 
-    private static final int RATE_LIMIT_CODE = 429;
-
     //this includes a-zA-Z1-9_
     //compile the pattern only on plugin enable -> and this have to be thread-safe
     private final Pattern validNameMatcher = Pattern.compile("^\\w{2,16}$");
@@ -53,6 +52,7 @@ public class MojangApiConnector {
     private final Map<Object, Object> requests = CommonUtil.buildCache(10, -1);
     private final SSLSocketFactory sslFactory;
     private final int rateLimit;
+
     private long lastRateLimit;
 
     protected final Gson gson = new GsonBuilder().registerTypeAdapter(UUID.class, new UUIDTypeAdapter()).create();
@@ -110,7 +110,7 @@ public class MojangApiConnector {
             }
             //204 - no content for not found
         } catch (Exception ex) {
-            logger.log(Level.SEVERE, "Failed to check if player has a paid account", ex);
+            logger.error("Failed to check if player has a paid account", ex);
         }
 
         return Optional.empty();
@@ -161,13 +161,13 @@ public class MojangApiConnector {
                 try {
                     InetAddress address = InetAddress.getByName(localAddress);
                     if (!address.isAnyLocalAddress()) {
-                        logger.log(Level.WARNING, "Submitted IP-Address is not local {0}", address);
+                        logger.warn("Submitted IP-Address is not local {0}", address);
                         continue;
                     }
 
                     addresses.add(address);
                 } catch (UnknownHostException ex) {
-                    logger.log(Level.SEVERE, "IP-Address is unknown to us", ex);
+                    logger.error("IP-Address is unknown to us", ex);
                 }
             }
 

core/src/main/java/com/github/games647/fastlogin/core/shared/FastLoginCore.java

@@ -23,7 +23,6 @@ import java.util.UUID;
 import java.util.concurrent.ConcurrentHashMap;
 import java.util.concurrent.ConcurrentMap;
 import java.util.function.Function;
-import java.util.logging.Level;
 import java.util.stream.Collectors;
 
 import net.md_5.bungee.config.Configuration;
@@ -72,7 +71,7 @@ public class FastLoginCore<P extends C, C, T extends PlatformPlugin<C>> {
                         }
                     });
         } catch (IOException ioEx) {
-            plugin.getLogger().log(Level.INFO, "Failed to load yaml files", ioEx);
+            plugin.getLog().error("Failed to load yaml files", ioEx);
         }
 
         List<String> ipAddresses = config.getStringList("ip-addresses");
@@ -134,7 +133,7 @@ public class FastLoginCore<P extends C, C, T extends PlatformPlugin<C>> {
             storage.createTables();
             return true;
         } catch (Exception ex) {
-            plugin.getLogger().log(Level.SEVERE, "Failed to setup database. Disabling plugin...", ex);
+            plugin.getLog().warn("Failed to setup database. Disabling plugin...", ex);
             return false;
         }
     }
@@ -180,7 +179,7 @@ public class FastLoginCore<P extends C, C, T extends PlatformPlugin<C>> {
                 }
             }
         } catch (IOException ioExc) {
-            plugin.getLogger().log(Level.SEVERE, "Cannot create plugin folder " + dataFolder, ioExc);
+            plugin.getLog().error("Cannot create plugin folder {}", dataFolder, ioExc);
         }
     }
 

core/src/main/java/com/github/games647/fastlogin/core/shared/ForceLoginManagement.java

@@ -4,8 +4,6 @@ import com.github.games647.fastlogin.core.AuthStorage;
 import com.github.games647.fastlogin.core.PlayerProfile;
 import com.github.games647.fastlogin.core.hooks.AuthPlugin;
 
-import java.util.logging.Level;
-
 public abstract class ForceLoginManagement<P extends C, C, L extends LoginSession, T extends PlatformPlugin<C>>
         implements Runnable {
 
@@ -66,12 +64,12 @@ public abstract class ForceLoginManagement<P extends C, C, L extends LoginSessio
                 storage.save(playerProfile);
             }
         } catch (Exception ex) {
-            core.getPlugin().getLogger().log(Level.WARNING, "ERROR ON FORCE LOGIN", ex);
+            core.getPlugin().getLog().warn("ERROR ON FORCE LOGIN", ex);
         }
     }
 
     public boolean forceRegister(P player) {
-        core.getPlugin().getLogger().log(Level.INFO, "Register player {0}", getName(player));
+        core.getPlugin().getLog().info("Register player {}", getName(player));
 
         String generatedPassword = core.getPasswordGenerator().getRandomPassword(player);
         boolean success = core.getAuthPluginHook().forceRegister(player, generatedPassword);
@@ -86,7 +84,7 @@ public abstract class ForceLoginManagement<P extends C, C, L extends LoginSessio
     }
 
     public boolean forceLogin(P player) {
-        core.getPlugin().getLogger().log(Level.INFO, "Logging player {0} in", getName(player));
+        core.getPlugin().getLog().info("Logging player {} in", getName(player));
         boolean success = core.getAuthPluginHook().forceLogin(player);
 
         if (success) {

core/src/main/java/com/github/games647/fastlogin/core/shared/JoinManagement.java

@@ -5,7 +5,6 @@ import com.github.games647.fastlogin.core.hooks.AuthPlugin;
 
 import java.util.Optional;
 import java.util.UUID;
-import java.util.logging.Level;
 
 import net.md_5.bungee.config.Configuration;
 
@@ -32,7 +31,7 @@ public abstract class JoinManagement<P extends C, C, S extends LoginSource> {
         try {
             if (profile.getUserId() == -1) {
                 if (core.getPendingLogin().remove(ip + username) != null && config.get("secondAttemptCracked", false)) {
-                    core.getPlugin().getLogger().log(Level.INFO, "Second attempt login -> cracked {0}", username);
+                    core.getPlugin().getLog().info("Second attempt login -> cracked {}", username);
 
                     //first login request failed so make a cracked session
                     startCrackedSession(source, profile, username);
@@ -61,12 +60,12 @@ public abstract class JoinManagement<P extends C, C, S extends LoginSource> {
                 startCrackedSession(source, profile, username);
             }
         } catch (Exception ex) {
-            core.getPlugin().getLogger().log(Level.SEVERE, "Failed to check premium state", ex);
+            core.getPlugin().getLog().error("Failed to check premium state", ex);
         }
     }
 
     private boolean checkPremiumName(S source, String username, PlayerProfile profile) throws Exception {
-        core.getPlugin().getLogger().log(Level.FINER, "GameProfile {0} uses a premium username", username);
+        core.getPlugin().getLog().debug("GameProfile {} uses a premium username", username);
         if (core.getConfig().get("autoRegister", false) && (authHook == null || !authHook.isRegistered(username))) {
             requestPremiumLogin(source, profile, username, false);
             return true;
@@ -81,7 +80,7 @@ public abstract class JoinManagement<P extends C, C, S extends LoginSource> {
             PlayerProfile profile = core.getStorage().loadProfile(premiumUUID);
             if (profile != null) {
                 //uuid exists in the database
-                core.getPlugin().getLogger().log(Level.FINER, "GameProfile {0} changed it's username", premiumUUID);
+                core.getPlugin().getLog().info("GameProfile {} changed it's username", premiumUUID);
 
                 //update the username to the new one in the database
                 profile.setPlayerName(username);

core/src/main/java/com/github/games647/fastlogin/core/shared/PlatformPlugin.java

@@ -6,7 +6,8 @@ import com.google.common.net.HostAndPort;
 import java.io.File;
 import java.util.List;
 import java.util.concurrent.ThreadFactory;
-import java.util.logging.Logger;
+
+import org.slf4j.Logger;
 
 public interface PlatformPlugin<C> {
 
@@ -14,7 +15,7 @@ public interface PlatformPlugin<C> {
 
     File getDataFolder();
 
-    Logger getLogger();
+    Logger getLog();
 
     void sendMessage(C receiver, String message);