UUIDFetcher.java

package nl.sugcube.crystalquest.uuid;

import org.json.simple.JSONArray;
import org.json.simple.JSONObject;
import org.json.simple.JSONValue;
import org.json.simple.parser.JSONParser;

import java.io.DataOutputStream;
import java.io.InputStreamReader;
import java.net.HttpURLConnection;
import java.net.URL;
import java.util.*;
import java.util.concurrent.Callable;

/**
 * @author SugarCaney
 */
public class UUIDFetcher implements Callable<Map<String, UUID>> {

    private static final int MAX_SEARCH = 100;
    private static final String PROFILE_URL = "https://api.mojang.com/profiles/page/";
    private static final String AGENT = "minecraft";
    private final JSONParser jsonParser = new JSONParser();
    private final List<String> names;

    public UUIDFetcher(List<String> names) {
        this.names = Collections.unmodifiableList(new ArrayList<>(names));
    }

    public Map<String, UUID> call() throws Exception {
        Map<String, UUID> uuidMap = new HashMap<>();
        String body = buildBody(names);
        for (int i = 1; i < MAX_SEARCH; i++) {
            HttpURLConnection connection = createConnection(i);
            writeBody(connection, body);
            JSONObject jsonObject = (JSONObject)jsonParser
                    .parse(new InputStreamReader(connection.getInputStream()));
            JSONArray array = (JSONArray)jsonObject.get("profiles");
            Number count = (Number)jsonObject.get("size");
            if (count.intValue() == 0) {
                break;
            }
            for (Object profile : array) {
                JSONObject jsonProfile = (JSONObject)profile;
                String id = (String)jsonProfile.get("id");
                String name = (String)jsonProfile.get("name");
                UUID uuid = UUID.fromString(id.substring(0, 8) + "-"
                        + id.substring(8, 12) + "-" + id.substring(12, 16)
                        + "-" + id.substring(16, 20) + "-"
                        + id.substring(20, 32));
                uuidMap.put(name, uuid);
            }
        }
        return uuidMap;
    }

    private static void writeBody(HttpURLConnection connection, String body)
            throws Exception {
        DataOutputStream writer = new DataOutputStream(
                connection.getOutputStream());
        writer.write(body.getBytes());
        writer.flush();
        writer.close();
    }

    private static HttpURLConnection createConnection(int page)
            throws Exception {
        URL url = new URL(PROFILE_URL + page);
        HttpURLConnection connection = (HttpURLConnection)url.openConnection();
        connection.setRequestMethod("POST");
        connection.setRequestProperty("Content-Type", "application/json");
        connection.setUseCaches(false);
        connection.setDoInput(true);
        connection.setDoOutput(true);
        return connection;
    }

    @SuppressWarnings("unchecked")
    private static String buildBody(List<String> names) {
        List<JSONObject> lookups = new ArrayList<>();
        for (String name : names) {
            JSONObject obj = new JSONObject();
            obj.put("name", name);
            obj.put("agent", AGENT);
            lookups.add(obj);
        }
        return JSONValue.toJSONString(lookups);
    }
}