如何从URL对应的JSON文件中获取多个UUID用于Minecraft客户端披风判定

核心优化说明 #

你原有代码存在逻辑缺陷：hasCape方法每次被调用都会往players列表重复插入UUID，会导致列表体积持续膨胀、判断效率越来越低，本次实现同时修复了该问题。

本次实现无需额外引入依赖，直接复用Minecraft自带的Gson库完成JSON解析，采用异步拉取逻辑避免阻塞游戏主线程，同时增加降级逻辑保证网络异常时功能可用。

实现代码 #

import com.google.gson.Gson;
import com.google.gson.annotations.SerializedName;
import java.io.BufferedReader;
import java.io.InputStreamReader;
import java.net.HttpURLConnection;
import java.net.URL;
import java.util.ArrayList;
import java.util.List;
import java.util.UUID;
import net.minecraft.client.player.AbstractClientPlayer;

public class CosmeticsManager {
    private static final List<UUID> capePlayers = new ArrayList<>();
    private static final String COSMETICS_JSON_URL = "https://raw.githubusercontent.com/shovelmods/shovelmods.github.io/main/cosmetics.json";
    private static final Gson GSON_INSTANCE = new Gson();

    // 类加载时启动异步线程拉取UUID列表，不阻塞游戏启动
    static {
        new Thread(() -> {
            try {
                loadRemoteUuidList();
            } catch (Exception e) {
                // 拉取失败时加载默认硬编码UUID作为降级
                loadDefaultUuidList();
                e.printStackTrace();
            }
        }, "Cosmetics-UUID-Fetcher").start();
    }

    // 从线上拉取并解析UUID列表
    private static void loadRemoteUuidList() throws Exception {
        URL url = new URL(COSMETICS_JSON_URL);
        HttpURLConnection connection = (HttpURLConnection) url.openConnection();
        connection.setRequestMethod("GET");
        connection.setConnectTimeout(5000);
        connection.setReadTimeout(5000);
        // 设置UA避免GitHub raw接口拦截请求
        connection.setRequestProperty("User-Agent", "Mozilla/5.0 (Windows NT 10.0; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/120.0.0.0 Safari/537.36");

        BufferedReader reader = new BufferedReader(new InputStreamReader(connection.getInputStream()));
        CosmeticEntry[] entries = GSON_INSTANCE.fromJson(reader, CosmeticEntry[].class);
        reader.close();
        connection.disconnect();

        synchronized (capePlayers) {
            capePlayers.clear();
            for (CosmeticEntry entry : entries) {
                try {
                    capePlayers.add(UUID.fromString(entry.uuid));
                } catch (IllegalArgumentException ignored) {
                    // 自动忽略格式错误的UUID
                }
            }
        }
    }

    // 降级逻辑：加载原有硬编码的UUID
    private static void loadDefaultUuidList() {
        synchronized (capePlayers) {
            capePlayers.clear();
            capePlayers.add(UUID.fromString("288f696b-44d2-4915-a8cc-aa3fd5ea889c"));
            capePlayers.add(UUID.fromString("ecad61c5-6a42-4018-b1c7-6c5c19ec1cd1"));
            capePlayers.add(UUID.fromString("093f3473-587b-4a2a-b50f-f4a136e9033b"));
            capePlayers.add(UUID.fromString("a22ab0ef-18b2-4cc6-ac17-2d9ae40a42ee"));
        }
    }

    public static boolean hasCape(AbstractClientPlayer player) {
        if (player == null) return false;
        synchronized (capePlayers) {
            return capePlayers.contains(player.getUniqueID());
        }
    }

    // 线上JSON结构对应的映射类，无需解析的字段不用定义
    private static class CosmeticEntry {
        @SerializedName("uuid")
        String uuid;
    }
}

功能说明 #

• 后续新增饰品权限仅需要修改GitHub上的JSON文件，不需要重新打包发布客户端，用户重启游戏后会自动拉取最新的UUID列表
• 加了线程锁保证多线程读写安全，不会出现并发异常
• 网络异常时自动降级使用本地硬编码的UUID列表，不会导致饰品功能完全失效
• 判断逻辑复用List的contains方法，比手动遍历更简洁高效

内容的提问来源于stack exchange，提问作者jamig