Nms Packet Sender

NMS Packet Sender / NMS 封包發送器

技能名稱 / Skill Name

nms-packet-sender

目的 / Purpose

產生標準的 NMS 封包發送工具類，涵蓋單人、多人、廣播、延遲發送等情境。所有發送點透過 ServerPlayer.connection.send(Packet<?>) 進入 Netty write queue。

NMS 版本需求 / NMS Version Requirements

• Paper 1.21 – 1.21.3
• Paperweight userdev 1.7.2+
• Mojang mappings（已由 Paper 1.20.5+ 原生支援）

觸發條件 / Triggers

• 「封包發送」「packet sender」「自定義封包」「custom packet」
• 「Clientbound」「推送封包」「send packet」
• 「PacketPlayOut」「ProtocolLib 替代」

輸入參數 / Inputs

輸出產物 / Outputs

• PacketSender.java — 主工具類（static 方法）
• PacketBuilder.java（選）— 常見 Clientbound 封包建構器

Paperweight 建置設定 / Build Setup

參見 Skills/paper-nms/PLATFORM.md。關鍵依賴：

dependencies {
    paperweight.paperDevBundle('1.21.1-R0.1-SNAPSHOT')
}

代碼範本 / Code Template

PacketSender.java

package com.example.network;

import net.minecraft.network.protocol.Packet;
import net.minecraft.server.level.ServerPlayer;
import org.bukkit.Bukkit;
import org.bukkit.World;
import org.bukkit.craftbukkit.v1_21_R1.entity.CraftPlayer;
import org.bukkit.entity.Player;
import org.bukkit.plugin.Plugin;

import java.util.Collection;
import java.util.Objects;

@SuppressWarnings("UnstableApiUsage")
public final class PacketSender {

    private PacketSender() {}

    /** 發送封包給單一玩家（任意執行緒皆可）。 */
    public static void send(Player player, Packet<?> packet) {
        Objects.requireNonNull(player, "player");
        Objects.requireNonNull(packet, "packet");

        ServerPlayer nms = ((CraftPlayer) player).getHandle();
        if (nms.connection == null) return; // 玩家已離線
        nms.connection.send(packet);
    }

    /** 批次發送給多位玩家。 */
    public static void sendAll(Collection<? extends Player> players, Packet<?> packet) {
        for (Player p : players) send(p, packet);
    }

    /** 對伺服器全體玩家廣播封包。 */
    public static void broadcast(Packet<?> packet) {
        sendAll(Bukkit.getOnlinePlayers(), packet);
    }

    /** 對指定世界的玩家廣播封包。 */
    public static void broadcastWorld(World world, Packet<?> packet) {
        sendAll(world.getPlayers(), packet);
    }

    /** 延遲 N tick 後在主執行緒發送。 */
    public static void sendLater(Plugin plugin, Player player, Packet<?> packet, long delayTicks) {
        Bukkit.getScheduler().runTaskLater(plugin, () -> send(player, packet), delayTicks);
    }

    /**
     * 以非同步方式發送（封包需已建構完成，不可在此存取世界狀態）。
     * 適合大量封包批次，不阻塞主執行緒。
     */
    public static void sendAsync(Plugin plugin, Player player, Packet<?> packet) {
        Bukkit.getScheduler().runTaskAsynchronously(plugin, () -> send(player, packet));
    }
}

PacketBuilder.java（常見 Clientbound 範例）

package com.example.network;

import io.netty.buffer.Unpooled;
import net.kyori.adventure.text.Component;
import net.kyori.adventure.text.serializer.gson.GsonComponentSerializer;
import net.minecraft.network.FriendlyByteBuf;
import net.minecraft.network.chat.MutableComponent;
import net.minecraft.network.protocol.common.ClientboundCustomPayloadPacket;
import net.minecraft.network.protocol.common.custom.CustomPacketPayload;
import net.minecraft.network.protocol.game.ClientboundSetActionBarTextPacket;
import net.minecraft.network.protocol.game.ClientboundSetTitleTextPacket;
import net.minecraft.resources.ResourceLocation;

@SuppressWarnings("UnstableApiUsage")
public final class PacketBuilder {

    private PacketBuilder() {}

    /** 建立 Action Bar 文字封包。 */
    public static ClientboundSetActionBarTextPacket actionBar(Component message) {
        String json = GsonComponentSerializer.gson().serialize(message);
        MutableComponent nmsComponent = net.minecraft.network.chat.Component.Serializer
                .fromJson(json, net.minecraft.core.RegistryAccess.EMPTY);
        return new ClientboundSetActionBarTextPacket(nmsComponent);
    }

    /** 建立 Title 封包。 */
    public static ClientboundSetTitleTextPacket title(Component title) {
        String json = GsonComponentSerializer.gson().serialize(title);
        MutableComponent nmsComponent = net.minecraft.network.chat.Component.Serializer
                .fromJson(json, net.minecraft.core.RegistryAccess.EMPTY);
        return new ClientboundSetTitleTextPacket(nmsComponent);
    }

    /** 建立自定義 Plugin Message 封包（CustomPayload）。 */
    public static ClientboundCustomPayloadPacket customPayload(ResourceLocation channel, byte[] data) {
        CustomPacketPayload payload = new CustomPacketPayload() {
            @Override
            public void write(FriendlyByteBuf buf) {
                buf.writeBytes(data);
            }
            @Override
            public ResourceLocation id() {
                return channel;
            }
        };
        return new ClientboundCustomPayloadPacket(payload);
    }
}

推薦目錄結構 / Recommended Directory Structure

src/main/java/com/example/
├── MyNmsPlugin.java
└── network/
    ├── PacketSender.java
    └── PacketBuilder.java

執行緒安全注意事項 / Thread Safety

• ✅ PacketSender.send() 內部呼叫 connection.send()，可在任何執行緒呼叫（Netty 會自行排入 write queue）
• ⚠️ 封包建構若依賴世界狀態（Entity ID、Block position），必須在主執行緒完成
• ⚠️ connection 欄位在玩家離線時為 null，send 前需檢查
• 詳見 Skills/_shared/nms-threading.md

失敗回退 / Fallback