完成基本功能

src/main/java/cn/cnklp/studio/UnionBanClientSpigot/BanTask.java

@@ -0,0 +1,46 @@
+package cn.cnklp.studio.UnionBanClientSpigot;
+
+import org.bukkit.command.CommandSender;
+import org.bukkit.scheduler.BukkitRunnable;
+
+public class BanTask extends BukkitRunnable {
+    private final String username;
+    private final CommandSender sender;
+    private final ClientPlugin plugin;
+
+    public BanTask(ClientPlugin plugin, CommandSender sender, String username) {
+        this.sender = sender;
+        this.plugin = plugin;
+        this.username = username;
+    }
+
+    @Override
+    public void run() {
+        String uuid;
+        sender.sendMessage("Querying UUID of player " + username + " from Mojang server...");
+        try {
+            uuid = PlayerUUID.FromUsername(username);
+            sender.sendMessage("UUID of player " + username + " is " + uuid + ".");
+        } catch (Exception e) {
+            if (e.getMessage().equals("Player does not exist!")) {
+                sender.sendMessage("Player " + username + " does not exist!");
+            } else {
+                sender.sendMessage("Cannot connect to Mojang server!");
+            }
+            return;
+        }
+        try {
+            PlayerUUID.Ban(plugin.ServerAddress, uuid);
+            sender.sendMessage("Banned player " + username + " successfully!");
+        } catch (Exception e) {
+            if (e.getMessage().equals("Record exists!")) {
+                sender.sendMessage("Player " + username + " is already in the UnionBan list!");
+            } else if (e.getMessage().equals("Not logged in!")) {
+                sender.sendMessage("You have not logged in!");
+            } else {
+                e.printStackTrace();
+                sender.sendMessage("Failed to ban player " + username + "!");
+            }
+        }
+    }
+}

src/main/java/cn/cnklp/studio/UnionBanClientSpigot/ClientPlugin.java

@@ -0,0 +1,33 @@
+package cn.cnklp.studio.UnionBanClientSpigot;
+
+import org.bukkit.Bukkit;
+import org.bukkit.event.HandlerList;
+import org.bukkit.plugin.java.JavaPlugin;
+import org.bukkit.scheduler.BukkitTask;
+
+import java.net.CookieHandler;
+import java.net.CookieManager;
+import java.net.CookiePolicy;
+import java.util.Objects;
+
+public class ClientPlugin extends JavaPlugin {
+    public String ServerAddress = "https://api.unionban.icu";
+    public BukkitTask login = null;
+
+    @Override
+    public void onEnable() {
+        CookieHandler.setDefault(new CookieManager(null, CookiePolicy.ACCEPT_ALL));
+        getServer().getPluginManager().registerEvents(new PlayerLoginListener(this), this);
+        getServer().getPluginManager().registerEvents(new WhitelistListener(this), this);
+        CommandsExecutor executor = new CommandsExecutor(this);
+        Objects.requireNonNull(this.getCommand("unionban")).setExecutor(executor);
+        Objects.requireNonNull(this.getCommand("unionban")).setTabCompleter(executor);
+        saveDefaultConfig();
+        new LoginTask(this, Bukkit.getConsoleSender()).runTaskAsynchronously(this);
+    }
+
+    @Override
+    public void onDisable() {
+        HandlerList.unregisterAll(this);
+    }
+}

src/main/java/cn/cnklp/studio/UnionBanClientSpigot/CommandsExecutor.java

@@ -0,0 +1,105 @@
+package cn.cnklp.studio.UnionBanClientSpigot;
+
+import org.bukkit.Bukkit;
+import org.bukkit.OfflinePlayer;
+import org.bukkit.command.Command;
+import org.bukkit.command.CommandSender;
+import org.bukkit.command.TabExecutor;
+
+import java.util.ArrayList;
+import java.util.List;
+
+public class CommandsExecutor implements TabExecutor {
+    private final ClientPlugin plugin;
+    private final List<String> SubCommands = new ArrayList<>();
+
+    public CommandsExecutor(ClientPlugin plugin) {
+        this.plugin = plugin;
+        SubCommands.add("help");
+        SubCommands.add("status");
+        SubCommands.add("login");
+        SubCommands.add("logout");
+        SubCommands.add("ban");
+        SubCommands.add("pardon");
+    }
+
+    @Override
+    public boolean onCommand(CommandSender sender, Command cmd, String label, String[] args) {
+        if (sender.hasPermission("unionban.account")) {
+            if (args.length == 3 && args[0].equals("login")) {
+                if (plugin.login != null) {
+                    plugin.login.cancel();
+                    plugin.login = null;
+                }
+                plugin.getConfig().set("username", args[1]);
+                plugin.getConfig().set("password", args[2]);
+                plugin.getConfig().set("api_key", "");
+                plugin.saveConfig();
+                new LoginTask(plugin, sender).runTaskAsynchronously(plugin);
+                return true;
+            }
+            if (args.length == 1 && args[0].equals("logout")) {
+                sender.sendMessage("Logging out...");
+                if (plugin.login != null) {
+                    plugin.login.cancel();
+                    plugin.login = null;
+                }
+                plugin.getConfig().set("username", "");
+                plugin.getConfig().set("password", "");
+                plugin.getConfig().set("api_key", "");
+                plugin.saveConfig();
+                new LogoutTask(plugin, sender).runTaskAsynchronously(plugin);
+                return true;
+            }
+        }
+        if (sender.hasPermission("unionban.ban")) {
+            if (args.length == 2 && args[0].equals("ban")) {
+                new BanTask(plugin, sender, args[1]).runTaskAsynchronously(plugin);
+                return true;
+            }
+            if (args.length == 2 && args[0].equals("pardon")) {
+                new PardonTask(plugin, sender, args[1]).runTaskAsynchronously(plugin);
+                return true;
+            }
+        }
+        if (sender.hasPermission("unionban.info")) {
+            if (args.length == 0) {
+                return false;
+            }
+            if (args.length == 1 && args[0].equals("help")) {
+                return false;
+            }
+            if (args.length == 1 && args[0].equals("status")) {
+                new GetServerStatusTask(plugin, sender).runTaskAsynchronously(plugin);
+                return true;
+            }
+            sender.sendMessage("Unknown command. Type \"/unionban help\" for help.");
+            return true;
+        }
+        sender.sendMessage("You do not have permission to execute this command!");
+        StringBuilder builder = new StringBuilder();
+        builder.append(cmd);
+        for (String arg : args) {
+            builder.append(" ");
+            builder.append(arg);
+        }
+        plugin.getLogger().warning(sender.getName() + " tried to execute command: " + builder);
+        return true;
+    }
+
+    @Override
+    public List<String> onTabComplete(CommandSender sender, Command cmd, String alias, String[] args) {
+        List<String> result = new ArrayList<>();
+        if (args.length == 1) {
+            result.addAll(SubCommands);
+        } else if (args.length == 2 && (args[0].equals("ban") || args[0].equals("pardon"))) {
+            for (OfflinePlayer player : Bukkit.getOfflinePlayers()) {
+                String name = player.getName();
+                if (name != null) {
+                    result.add(name);
+                }
+            }
+        }
+        return result;
+    }
+}

src/main/java/cn/cnklp/studio/UnionBanClientSpigot/GetServerStatusTask.java

@@ -0,0 +1,74 @@
+package cn.cnklp.studio.UnionBanClientSpigot;
+
+import com.fasterxml.jackson.databind.DeserializationFeature;
+import com.fasterxml.jackson.databind.ObjectMapper;
+import org.bukkit.command.CommandSender;
+import org.bukkit.scheduler.BukkitRunnable;
+
+import javax.net.ssl.HttpsURLConnection;
+import java.io.BufferedReader;
+import java.io.InputStreamReader;
+import java.net.URL;
+
+class ServerStatus {
+    public String version;
+}
+
+public class GetServerStatusTask extends BukkitRunnable {
+    private final ClientPlugin plugin;
+    private final CommandSender sender;
+
+    public GetServerStatusTask(ClientPlugin plugin, CommandSender sender) {
+        this.plugin = plugin;
+        this.sender = sender;
+    }
+
+    public static String GetVersion(String ServerAddress) throws Exception {
+        URL url = new URL(ServerAddress);
+        HttpsURLConnection con = (HttpsURLConnection) url.openConnection();
+        con.setReadTimeout(5000);
+        con.setConnectTimeout(5000);
+        con.setRequestProperty("User-Agent", "Mozilla/5.0");
+        con.setRequestProperty("Content-Type", "application/json");
+        con.setRequestMethod("GET");
+        con.setDoOutput(true);
+
+        int responseCode = con.getResponseCode();
+        if (responseCode != 200) {
+            con.disconnect();
+            throw new Exception("HTTP Response Code: " + responseCode);
+        }
+        BufferedReader reader = new BufferedReader(new InputStreamReader(con.getInputStream()));
+        StringBuilder builder = new StringBuilder();
+        String inputLine;
+        while ((inputLine = reader.readLine()) != null) {
+            builder.append(inputLine);
+        }
+        reader.close();
+
+        con.disconnect();
+
+        ObjectMapper objectMapper = new ObjectMapper();
+        objectMapper.configure(DeserializationFeature.FAIL_ON_UNKNOWN_PROPERTIES, false);
+        ServerStatus status = objectMapper.readValue(builder.toString(), ServerStatus.class);
+
+        return status.version;
+    }
+
+    @Override
+    public void run() {
+        sender.sendMessage("Querying server status...");
+        try {
+            String version = GetVersion(plugin.ServerAddress);
+            sender.sendMessage("UnionBan Server is ON! Version: " + version);
+            String username = LoginTask.GetLoginStatus(plugin.ServerAddress).username;
+            sender.sendMessage("Logged in as " + plugin.getConfig().getString("username") + ".");
+        } catch (Exception e) {
+            if (e.getMessage().equals("Not logged in!")) {
+                sender.sendMessage("You have not logged in!");
+            } else {
+                sender.sendMessage("Failed to connect to UnionBan server.");
+            }
+        }
+    }
+}

src/main/java/cn/cnklp/studio/UnionBanClientSpigot/KickPlayerTask.java

@@ -0,0 +1,20 @@
+package cn.cnklp.studio.UnionBanClientSpigot;
+
+import org.bukkit.Bukkit;
+import org.bukkit.scheduler.BukkitRunnable;
+
+import java.util.Objects;
+
+public class KickPlayerTask extends BukkitRunnable {
+    private final String username;
+    private final ClientPlugin plugin;
+
+    public KickPlayerTask(ClientPlugin plugin, String username) {
+        this.username = username;
+        this.plugin = plugin;
+    }
+
+    public void run() {
+        Objects.requireNonNull(Bukkit.getPlayer(username)).kickPlayer("You are in the UnionBan list!");
+    }
+}

src/main/java/cn/cnklp/studio/UnionBanClientSpigot/LoginTask.java

@@ -0,0 +1,216 @@
+package cn.cnklp.studio.UnionBanClientSpigot;
+
+import com.fasterxml.jackson.databind.DeserializationFeature;
+import com.fasterxml.jackson.databind.ObjectMapper;
+import org.bukkit.Bukkit;
+import org.bukkit.command.CommandSender;
+import org.bukkit.configuration.file.FileConfiguration;
+import org.bukkit.scheduler.BukkitRunnable;
+
+import javax.net.ssl.HttpsURLConnection;
+import java.io.BufferedReader;
+import java.io.DataOutputStream;
+import java.io.InputStreamReader;
+import java.net.URL;
+
+class LoginStatus {
+    public String username;
+    public String api_key;
+}
+
+class Expire {
+    public int expire;
+}
+
+class UserInfo {
+    public String account;
+    public String password;
+}
+
+public class LoginTask extends BukkitRunnable {
+    private final ClientPlugin plugin;
+    private final CommandSender sender;
+
+    public LoginTask(ClientPlugin plugin, CommandSender sender) {
+        this.plugin = plugin;
+        this.sender = sender;
+    }
+
+    private static int LoginViaKey(String ServerAddress, String api_key) throws Exception {
+        LoginStatus key = new LoginStatus();
+        key.api_key = api_key;
+
+        ObjectMapper mapper = new ObjectMapper();
+        String json = mapper.writeValueAsString(key);
+
+        String Address = ServerAddress + "/session/";
+        URL url = new URL(Address);
+        HttpsURLConnection con = (HttpsURLConnection) url.openConnection();
+        con.setReadTimeout(5000);
+        con.setConnectTimeout(5000);
+        con.setRequestProperty("User-Agent", "Mozilla/5.0");
+        con.setRequestProperty("Content-Type", "application/json");
+        con.setRequestMethod("PUT");
+        con.setDoOutput(true);
+
+        con.connect();
+
+        DataOutputStream stream = new DataOutputStream(con.getOutputStream());
+        stream.writeBytes(json);
+        stream.flush();
+        stream.close();
+
+        int responseCode = con.getResponseCode();
+
+        if (responseCode != 200) {
+            con.disconnect();
+            throw new Exception("Login failed!");
+        }
+
+        BufferedReader reader = new BufferedReader(new InputStreamReader(con.getInputStream()));
+        StringBuilder builder = new StringBuilder();
+        String inputLine;
+        while ((inputLine = reader.readLine()) != null) {
+            builder.append(inputLine);
+        }
+        reader.close();
+        con.disconnect();
+
+        mapper.configure(DeserializationFeature.FAIL_ON_UNKNOWN_PROPERTIES, false);
+        Expire expire = mapper.readValue(builder.toString(), Expire.class);
+
+        return expire.expire;
+    }
+
+    private static int LoginViaUsername(String ServerAddress, String username, String password) throws Exception {
+        UserInfo info = new UserInfo();
+        info.account = username;
+        info.password = password;
+
+        ObjectMapper mapper = new ObjectMapper();
+        String json = mapper.writeValueAsString(info);
+
+        String Address = ServerAddress + "/session/";
+        URL url = new URL(Address);
+        HttpsURLConnection con = (HttpsURLConnection) url.openConnection();
+        con.setReadTimeout(5000);
+        con.setConnectTimeout(5000);
+        con.setRequestProperty("User-Agent", "Mozilla/5.0");
+        con.setRequestProperty("Content-Type", "application/json");
+        con.setRequestMethod("POST");
+        con.setDoOutput(true);
+
+        con.connect();
+
+        DataOutputStream stream = new DataOutputStream(con.getOutputStream());
+        stream.writeBytes(json);
+        stream.flush();
+        stream.close();
+
+        int responseCode = con.getResponseCode();
+
+        if (responseCode != 200) {
+            con.disconnect();
+            throw new Exception("Login failed!");
+        }
+
+        BufferedReader reader = new BufferedReader(new InputStreamReader(con.getInputStream()));
+        StringBuilder builder = new StringBuilder();
+        String inputLine;
+        while ((inputLine = reader.readLine()) != null) {
+            builder.append(inputLine);
+        }
+        reader.close();
+        con.disconnect();
+
+        mapper.configure(DeserializationFeature.FAIL_ON_UNKNOWN_PROPERTIES, false);
+        Expire expire = mapper.readValue(builder.toString(), Expire.class);
+
+        return expire.expire;
+    }
+
+    public static LoginStatus GetLoginStatus(String ServerAddress) throws Exception {
+        URL url = new URL(ServerAddress + "/user/");
+        HttpsURLConnection con = (HttpsURLConnection) url.openConnection();
+        con.setReadTimeout(5000);
+        con.setConnectTimeout(5000);
+        con.setRequestProperty("User-Agent", "Mozilla/5.0");
+        con.setRequestProperty("Content-Type", "application/json");
+        con.setRequestMethod("GET");
+        con.setDoOutput(true);
+
+        int responseCode = con.getResponseCode();
+        if (responseCode != 200) {
+            con.disconnect();
+            throw new Exception("Not logged in!");
+        }
+        BufferedReader reader = new BufferedReader(new InputStreamReader(con.getInputStream()));
+        StringBuilder builder = new StringBuilder();
+        String inputLine;
+        while ((inputLine = reader.readLine()) != null) {
+            builder.append(inputLine);
+        }
+        reader.close();
+
+        con.disconnect();
+
+        ObjectMapper mapper = new ObjectMapper();
+        mapper.configure(DeserializationFeature.FAIL_ON_UNKNOWN_PROPERTIES, false);
+
+        return mapper.readValue(builder.toString(), LoginStatus.class);
+    }
+
+    @Override
+    public void run() {
+        FileConfiguration config = plugin.getConfig();
+        String username = config.getString("username");
+        String password = config.getString("password");
+        String api_key = config.getString("api_key");
+
+        sender.sendMessage("Logging in via api_key...");
+
+        if (api_key != null && !api_key.isEmpty()) {
+            try {
+                int expire = LoginViaKey(plugin.ServerAddress, api_key);
+                sender.sendMessage("Login success. The session will expires after " + expire + " seconds.");
+                plugin.login = new LoginTask(plugin, Bukkit.getConsoleSender()).runTaskLaterAsynchronously(plugin, expire * 20);
+                sender.sendMessage("Automated login scheduled.");
+                return;
+            } catch (Exception e) {
+                if (!e.getMessage().equals("Login failed!")) {
+                    sender.sendMessage("Failed to connect to UnionBan server.");
+                    sender.sendMessage("Failed to login!");
+                    return;
+                }
+            }
+        }
+
+        sender.sendMessage("Cannot login via api_key. Trying username and password...");
+
+        if (username != null && username.isEmpty()) {
+            sender.sendMessage("Username is empty.");
+            sender.sendMessage("Failed to login!");
+            return;
+        }
+
+        try {
+            int expire = LoginViaUsername(plugin.ServerAddress, username, password);
+            sender.sendMessage("Login success. Updating api_key...");
+            api_key = GetLoginStatus(plugin.ServerAddress).api_key;
+            sender.sendMessage("Got new api_key: " + api_key + ". Saving to file...");
+            config.set("api_key", api_key);
+            plugin.saveConfig();
+            sender.sendMessage("The session will expires after " + expire + " seconds.");
+            plugin.login = new LoginTask(plugin, Bukkit.getConsoleSender()).runTaskLaterAsynchronously(plugin, expire * 20);
+            sender.sendMessage("Automated login scheduled.");
+        } catch (Exception e) {
+            e.printStackTrace();
+            if (e.getMessage().equals("Login failed!")) {
+                sender.sendMessage("Cannot login via username and password!");
+            } else {
+                sender.sendMessage("Failed to connect to UnionBan server.");
+            }
+            sender.sendMessage("Failed to login!");
+        }
+    }
+}

src/main/java/cn/cnklp/studio/UnionBanClientSpigot/LogoutTask.java

@@ -0,0 +1,54 @@
+package cn.cnklp.studio.UnionBanClientSpigot;
+
+import org.bukkit.command.CommandSender;
+import org.bukkit.scheduler.BukkitRunnable;
+
+import javax.net.ssl.HttpsURLConnection;
+import java.net.URL;
+
+public class LogoutTask extends BukkitRunnable {
+    private final ClientPlugin plugin;
+    private final CommandSender sender;
+
+    public LogoutTask(ClientPlugin plugin, CommandSender sender) {
+        this.plugin = plugin;
+        this.sender = sender;
+    }
+
+    private static void Logout(String ServerAddress) throws Exception {
+        String Address = ServerAddress + "/session/";
+        URL url = new URL(Address);
+        HttpsURLConnection con = (HttpsURLConnection) url.openConnection();
+        con.setReadTimeout(5000);
+        con.setConnectTimeout(5000);
+        con.setRequestProperty("User-Agent", "Mozilla/5.0");
+        con.setRequestProperty("Content-Type", "application/json");
+        con.setRequestMethod("DELETE");
+        con.setDoOutput(true);
+
+        con.connect();
+
+        int responseCode = con.getResponseCode();
+
+        if (responseCode != 204) {
+            con.disconnect();
+            throw new Exception("You have not logged in!");
+        }
+
+        con.disconnect();
+    }
+
+    @Override
+    public void run() {
+        try {
+            Logout(plugin.ServerAddress);
+            sender.sendMessage("Logged out successfully.");
+        } catch (Exception e) {
+            if (e.getMessage().equals("You have not logged in!")) {
+                sender.sendMessage("You have not logged in!");
+            } else {
+                sender.sendMessage("Cannot connect to UnionBan server!");
+            }
+        }
+    }
+}

src/main/java/cn/cnklp/studio/UnionBanClientSpigot/PardonTask.java

@@ -0,0 +1,46 @@
+package cn.cnklp.studio.UnionBanClientSpigot;
+
+import org.bukkit.command.CommandSender;
+import org.bukkit.scheduler.BukkitRunnable;
+
+public class PardonTask extends BukkitRunnable {
+    private final String username;
+    private final CommandSender sender;
+    private final ClientPlugin plugin;
+
+    public PardonTask(ClientPlugin plugin, CommandSender sender, String username) {
+        this.sender = sender;
+        this.plugin = plugin;
+        this.username = username;
+    }
+
+    @Override
+    public void run() {
+        String uuid;
+        sender.sendMessage("Querying UUID of player " + username + " from Mojang server...");
+        try {
+            uuid = PlayerUUID.FromUsername(username);
+            sender.sendMessage("UUID of player " + username + " is " + uuid + ".");
+        } catch (Exception e) {
+            if (e.getMessage().equals("Player does not exist!")) {
+                sender.sendMessage("Player " + username + " does not exist!");
+            } else {
+                sender.sendMessage("Cannot connect to Mojang server!");
+            }
+            return;
+        }
+        try {
+            PlayerUUID.Pardon(plugin.ServerAddress, uuid);
+            sender.sendMessage("Removed player " + username + " from UnionBan list successfully!");
+        } catch (Exception e) {
+            if (e.getMessage().equals("Record does not exist!")) {
+                sender.sendMessage("Player " + username + " is not in the UnionBan list!");
+            } else if (e.getMessage().equals("Not logged in!")) {
+                sender.sendMessage("You have not logged in!");
+            } else {
+                e.printStackTrace();
+                sender.sendMessage("Failed to remove player " + username + " from UnionBan list!");
+            }
+        }
+    }
+}

src/main/java/cn/cnklp/studio/UnionBanClientSpigot/PlayerLoginListener.java

@@ -0,0 +1,20 @@
+package cn.cnklp.studio.UnionBanClientSpigot;
+
+import org.bukkit.Bukkit;
+import org.bukkit.event.EventHandler;
+import org.bukkit.event.Listener;
+import org.bukkit.event.player.PlayerLoginEvent;
+
+public final class PlayerLoginListener implements Listener {
+    private final ClientPlugin plugin;
+
+    public PlayerLoginListener(ClientPlugin plugin) {
+        this.plugin = plugin;
+    }
+
+    @EventHandler
+    public void onLogin(PlayerLoginEvent event) {
+        Bukkit.getLogger().info("Player " + event.getPlayer().getName() + " is logging in!");
+        new PlayerLoginTask(plugin, event.getPlayer().getName()).runTaskAsynchronously(plugin);
+    }
+}

src/main/java/cn/cnklp/studio/UnionBanClientSpigot/PlayerLoginTask.java

@@ -0,0 +1,29 @@
+package cn.cnklp.studio.UnionBanClientSpigot;
+
+import org.bukkit.Bukkit;
+import org.bukkit.scheduler.BukkitRunnable;
+
+public class PlayerLoginTask extends BukkitRunnable {
+    private final String username;
+    private final ClientPlugin plugin;
+
+    public PlayerLoginTask(ClientPlugin plugin, String username) {
+        this.plugin = plugin;
+        this.username = username;
+    }
+
+    @Override
+    public void run() {
+        try {
+            String uuid = PlayerUUID.FromUsername(username);
+            plugin.getLogger().info("UUID of " + username + ": " + uuid);
+            boolean isBanned = PlayerUUID.IsBan(plugin.ServerAddress, uuid);
+            plugin.getLogger().info("Player " + username + " is banned: " + isBanned);
+            if (isBanned) {
+                new KickPlayerTask(plugin, username).runTask(plugin);
+            }
+        } catch (Exception e) {
+            Bukkit.getLogger().warning("Failed to get information about player " + username + "!");
+        }
+    }
+}

src/main/java/cn/cnklp/studio/UnionBanClientSpigot/PlayerUUID.java

@@ -0,0 +1,121 @@
+package cn.cnklp.studio.UnionBanClientSpigot;
+
+import com.fasterxml.jackson.databind.DeserializationFeature;
+import com.fasterxml.jackson.databind.ObjectMapper;
+
+import javax.net.ssl.HttpsURLConnection;
+import java.io.BufferedReader;
+import java.io.InputStreamReader;
+import java.net.URL;
+
+class MojangUserInfo {
+    public String id;
+}
+
+public class PlayerUUID {
+    public static boolean IsBan(String ServerAddress, String uuid) throws Exception {
+        String Address = ServerAddress + "/record/uuid/" + uuid;
+        URL url = new URL(Address);
+        HttpsURLConnection con = (HttpsURLConnection) url.openConnection();
+        con.setReadTimeout(5000);
+        con.setConnectTimeout(5000);
+        con.setRequestProperty("User-Agent", "Mozilla/5.0");
+        con.setRequestProperty("Content-Type", "application/json");
+        con.setRequestMethod("GET");
+        con.setDoOutput(true);
+
+        int responseCode = con.getResponseCode();
+        con.disconnect();
+
+        if (responseCode == 200) {
+            return true;
+        } else if (responseCode == 404) {
+            return false;
+        } else {
+            throw new Exception("Failed to connect to UnionBan server!");
+        }
+    }
+
+    public static String FromUsername(String username) throws Exception {
+        String Address = "https://api.mojang.com/users/profiles/minecraft/" + username;
+        URL url = new URL(Address);
+        HttpsURLConnection con = (HttpsURLConnection) url.openConnection();
+        con.setReadTimeout(5000);
+        con.setConnectTimeout(5000);
+        con.setRequestProperty("User-Agent", "Mozilla/5.0");
+        con.setRequestProperty("Content-Type", "application/json");
+        con.setRequestMethod("GET");
+        con.setDoOutput(true);
+
+        int responseCode = con.getResponseCode();
+        if (responseCode == 204) {
+            throw new Exception("Player does not exist!");
+        } else if (responseCode != 200) {
+            con.disconnect();
+            throw new Exception("Failed to connect to Mojang API!");
+        }
+        BufferedReader reader = new BufferedReader(new InputStreamReader(con.getInputStream()));
+        StringBuilder builder = new StringBuilder();
+        String inputLine;
+        while ((inputLine = reader.readLine()) != null) {
+            builder.append(inputLine);
+        }
+        reader.close();
+
+        con.disconnect();
+
+        ObjectMapper objectMapper = new ObjectMapper();
+        objectMapper.configure(DeserializationFeature.FAIL_ON_UNKNOWN_PROPERTIES, false);
+        MojangUserInfo mojangUserInfo = objectMapper.readValue(builder.toString(), MojangUserInfo.class);
+
+        return mojangUserInfo.id.substring(0, 8) + "-" + mojangUserInfo.id.substring(8, 12) + "-" + mojangUserInfo.id.substring(12, 16) + "-" + mojangUserInfo.id.substring(16, 20) + "-" + mojangUserInfo.id.substring(20, 32);
+    }
+
+    public static void Ban(String ServerAddress, String uuid) throws Exception {
+        String Address = ServerAddress + "/record/uuid/" + uuid;
+        URL url = new URL(Address);
+        HttpsURLConnection con = (HttpsURLConnection) url.openConnection();
+        con.setReadTimeout(5000);
+        con.setConnectTimeout(5000);
+        con.setRequestProperty("User-Agent", "Mozilla/5.0");
+        con.setRequestProperty("Content-Type", "application/json");
+        con.setRequestMethod("PUT");
+        con.setDoOutput(true);
+
+        con.connect();
+        int responseCode = con.getResponseCode();
+        con.disconnect();
+
+        if (responseCode == 409) {
+            throw new Exception("Record exists!");
+        } else if (responseCode == 403) {
+            throw new Exception("Not logged in!");
+        } else if (responseCode != 200) {
+            throw new Exception("Ban failed!");
+        }
+    }
+
+    public static void Pardon(String ServerAddress, String uuid) throws Exception {
+        String Address = ServerAddress + "/record/uuid/" + uuid;
+        URL url = new URL(Address);
+        HttpsURLConnection con = (HttpsURLConnection) url.openConnection();
+        con.setReadTimeout(5000);
+        con.setConnectTimeout(5000);
+        con.setRequestProperty("User-Agent", "Mozilla/5.0");
+        con.setRequestProperty("Content-Type", "application/json");
+        con.setRequestMethod("DELETE");
+        con.setDoOutput(true);
+
+        con.connect();
+        int responseCode = con.getResponseCode();
+        con.disconnect();
+
+        if (responseCode == 404) {
+            throw new Exception("Record does not exist!");
+        } else if (responseCode == 403) {
+            throw new Exception("Not logged in!");
+        } else if (responseCode != 204) {
+            throw new Exception("Pardon failed!");
+        }
+    }
+}

src/main/java/cn/cnklp/studio/UnionBanClientSpigot/WhitelistListener.java

@@ -0,0 +1,32 @@
+package cn.cnklp.studio.UnionBanClientSpigot;
+
+import org.bukkit.event.EventHandler;
+import org.bukkit.event.Listener;
+import org.bukkit.event.player.PlayerCommandPreprocessEvent;
+import org.bukkit.event.server.ServerCommandEvent;
+
+public class WhitelistListener implements Listener {
+    private final ClientPlugin plugin;
+
+    public WhitelistListener(ClientPlugin plugin) {
+        this.plugin = plugin;
+    }
+
+    void onWhitelist(String prefix, String command) {
+        if (command.startsWith(prefix) && command.length() > prefix.length() + 2 && command.charAt(prefix.length() + 1) != ' ') {
+            new WhitelistTask(plugin, command.substring(prefix.length() + 1)).runTask(plugin);
+        }
+    }
+
+    @EventHandler
+    public void PlayerAction(PlayerCommandPreprocessEvent event) {
+        String prefix = "/whitelist add";
+        onWhitelist(prefix, event.getMessage());
+    }
+
+    @EventHandler
+    public void ServerAction(ServerCommandEvent event) {
+        String prefix = "whitelist add";
+        onWhitelist(prefix, event.getCommand());
+    }
+}

src/main/java/cn/cnklp/studio/UnionBanClientSpigot/WhitelistTask.java

@@ -0,0 +1,30 @@
+package cn.cnklp.studio.UnionBanClientSpigot;
+
+import org.bukkit.Bukkit;
+import org.bukkit.ChatColor;
+import org.bukkit.scheduler.BukkitRunnable;
+
+public class WhitelistTask extends BukkitRunnable {
+    private final String username;
+    private final ClientPlugin plugin;
+
+    public WhitelistTask(ClientPlugin plugin, String username) {
+        this.username = username;
+        this.plugin = plugin;
+    }
+
+    @Override
+    public void run() {
+        try {
+            String uuid = PlayerUUID.FromUsername(username);
+            plugin.getLogger().info("UUID of " + username + ": " + uuid);
+            boolean isBanned = PlayerUUID.IsBan(plugin.ServerAddress, uuid);
+            plugin.getLogger().info("Player " + username + " is banned: " + isBanned);
+            if (isBanned) {
+                Bukkit.broadcastMessage(ChatColor.RED + "[UnionBan] Player " + username + " is in the UnionBan list!");
+            }
+        } catch (Exception e) {
+            Bukkit.getLogger().warning("Failed to get information about player " + username + "!");
+        }
+    }
+}

src/main/resources/config.yml

@@ -0,0 +1,4 @@
+# Do NOT change this file manually!
+username: ""
+password: ""
+api_key: ""

src/main/resources/plugin.yml

@@ -0,0 +1,24 @@
+name: UnionBan-Client
+version: "1.0"
+api-version: "1.15"
+main: cn.cnklp.studio.UnionBanClientSpigot.ClientPlugin
+commands:
+  unionban:
+    description: UnionBan-Client
+    usage: |
+      /unionban help - Show this help.
+      /unionban status - Show status of UnionBan plugin and server.
+      /unionban login <username> <password> - Login to UnionBan server.
+      /unionban logout - Logout from UnionBan server.
+      /unionban ban <player> - Add <player> to UnionBan server(requires login).
+      /unionban pardon <player> - Remove <player> from UnionBan server(requires login).
+permissions:
+  unionban.info:
+    description: Allow user to get help and status of UnionBan plugin and server.
+    default: true
+  unionban.account:
+    description: Allow user to login or logout.
+    default: op
+  unionban.ban:
+    description: Allow user to add or remove player from UnionBan list.
+    default: op