PlayerNameCache.java

package gigaherz.enderthing.client;

import com.google.common.collect.Maps;
import com.google.gson.stream.JsonReader;
import com.google.gson.stream.JsonToken;

import java.io.IOException;
import java.io.InputStreamReader;
import java.net.MalformedURLException;
import java.net.URL;
import java.util.Map;
import java.util.UUID;
import java.util.concurrent.ExecutorService;
import java.util.concurrent.Executors;

public class PlayerNameCache
{
    private static class PlayerNameRequest
    {
        public boolean complete;
        public String lastKnownName;
        public long lastKnownDate;
        public long lastQueryDate;

        public String getLastKnownName()
        {
            if(!complete)
                return null;

            return lastKnownName;
        }

        public boolean isOld()
        {
            return (System.currentTimeMillis() - lastQueryDate) > (24L * 3600L * 1000L);
        }
    }

    private static Map<UUID, PlayerNameRequest> cache = Maps.newHashMap();

    public static String queryNameFromUUID(UUID uuid)
    {
        PlayerNameRequest req = cache.get(uuid);
        if(req == null || req.isOld())
        {
            req = startNameRequest(uuid);
        }

        return req.getLastKnownName();
    }

    static ExecutorService executor = Executors.newCachedThreadPool();
    private static PlayerNameRequest startNameRequest(UUID uuid)
    {
        PlayerNameRequest req = new PlayerNameRequest();

        cache.put(uuid, req);

        executor.execute(() -> {
            try
            {
                URL url = new URL("https://api.mojang.com/user/profiles/" + uuid.toString().replace("-","") + "/names");

                JsonReader input = new JsonReader(new InputStreamReader(url.openStream()));

                String lastKnownName = null;
                long lastKnownDate = -1;

                input.beginArray();

                while (input.hasNext())
                {
                    if (input.peek() != JsonToken.BEGIN_OBJECT)
                    {
                        continue;
                    }

                    String name = null;
                    long changeDate = 0;

                    input.beginObject();
                    while (input.hasNext())
                    {
                        String id = input.nextName();
                        if (id.equals("name"))
                        {
                            name = input.nextString();
                        }
                        else if(id.equals("changedToAt"))
                        {
                            changeDate = input.nextLong();
                        }
                    }
                    input.endObject();

                    if(changeDate > lastKnownDate)
                    {
                        lastKnownDate = changeDate;
                        lastKnownName = name;
                    }
                }

                input.endArray();
                input.close();

                req.lastKnownName = lastKnownName;
                req.lastKnownDate = lastKnownDate;
                req.complete = true;
            }
            catch (MalformedURLException e)
            {
                req.complete = true;
            }
            catch (IOException e)
            {
                e.printStackTrace();
            }
        });

        return req;
    }
}