New Bytebuf API

[Lumine1909]

由于Paper重写了Bukkit内部处理事件的逻辑 通过创建匿名类+static final modifier内联插件中事件处理方法的MethodHandler 使用Bukkit事件系统传递PacketEvent将不再产生由于反射导致的额外开销
我们可以重新设计一部分这个API 以提升性能和便捷性

[Lumine1909]

测试喵 Code review喵

我的测试用例

加载后所有玩家都能使用F3+F4切换模式（
onPacketOut 两个版本都测试成功

package io.github.lumine1909;

import org.bukkit.Bukkit;
import org.bukkit.GameMode;
import org.bukkit.entity.Player;
import org.bukkit.event.EventHandler;
import org.bukkit.event.Listener;
import org.bukkit.plugin.java.JavaPlugin;
import org.leavesmc.leaves.bytebuf.PacketType;
import org.leavesmc.leaves.event.bytebuf.PacketInEvent;
import org.leavesmc.leaves.event.bytebuf.PacketOutEvent;

public class DemoPlugin extends JavaPlugin implements Listener {

  public static DemoPlugin plugin;

  @Override
  public void onEnable() {
      plugin = this;
      Bukkit.getPluginManager().registerEvents(this, plugin);
  }

  @EventHandler
  public void onPacketOut(PacketOutEvent e) {
      if (e.getPacketType() != PacketType.Clientbound.ENTITY_EVENT) {
          return;
      }
      e.getBytebuf().writerIndex(4).writeByte(28);
      //e.setBytebuf(Bytebuf.buf().writeInt(e.getBytebuf().readInt()).writeByte(28));
  }

  @EventHandler
  public void onPacketIn(PacketInEvent e) {
      if (e.getPacketType() != PacketType.Serverbound.CHANGE_GAME_MODE) {
          return;
      }
      e.setCancelled(true);
      Player player = e.getAudience().getPlayer();
      if (player == null) {
          return;
      }
      GameMode gameMode = switch (e.getBytebuf().readByte()) {
          case 0 -> GameMode.SURVIVAL;
          case 1 -> GameMode.CREATIVE;
          case 2 -> GameMode.ADVENTURE;
          case 3 -> GameMode.SPECTATOR;
          default -> throw new IllegalStateException();
      };
      Bukkit.getScheduler().runTask(plugin, () -> player.setGameMode(gameMode));
  }
}