An update checker based based on my Github updater.

BitbucketUpdater.java

package fr.skyost.bitbucket;

import java.io.BufferedReader;
import java.io.InputStream;
import java.io.InputStreamReader;
import java.net.HttpURLConnection;
import java.net.URL;
import java.nio.charset.StandardCharsets;
import java.util.regex.Pattern;

import com.eclipsesource.json.Json;
import com.eclipsesource.json.JsonArray;

/**
 * An update checker based based on my Github updater.
 * 
 * @author Skyost.
 */

public class BitbucketUpdater extends Thread {
	
	public static final String ENDPOINT = "https://api.bitbucket.org/2.0/repositories/%s/%s/downloads";
	public static final String USER_AGENT = "BitbucketUpdater by Skyost";
	
	private final String username;
	private final String repo;
	private final String projectName;
	private final String localVersion;
	private final BitbucketResultListener caller;
	
	/**
	 * Creates a new <b>BitbucketUpdater</b> instance.
	 * 
	 * @param username Bitbucket username.
	 * @param repo Bitbucket repo.
	 * @param projectName Your project name (<i>projectName</i> v<i>localVersion</i>).
	 * @param localVersion Your project's local version (<i>name</i> v<i>localVersion</i>).
	 * @param caller The caller.
	 */
	
	public BitbucketUpdater(final String username, final String repo, final String projectName, final String localVersion, final BitbucketResultListener caller) {
		this.username = username;
		this.repo = repo;
		this.projectName = projectName;
		this.localVersion = localVersion;
		this.caller = caller;
	}
	
	@Override
	public final void run() {
		caller.updaterStarted();
		try {
			final HttpURLConnection connection = (HttpURLConnection)new URL(String.format(ENDPOINT, username, repo)).openConnection();
			connection.addRequestProperty("User-Agent", USER_AGENT);
			final String response = connection.getResponseCode() + " " + connection.getResponseMessage();
			caller.updaterResponse(response);
			if(!response.startsWith("2")) {
				throw new Exception("Invalid response : " + response);
			}
			final InputStream input = connection.getInputStream();
			final InputStreamReader inputStreamReader = new InputStreamReader(input, StandardCharsets.UTF_8);
			final BufferedReader bufferedReader = new BufferedReader(inputStreamReader);
			final JsonArray releases = Json.parse(bufferedReader.readLine()).asObject().get("values").asArray();
			input.close();
			inputStreamReader.close();
			bufferedReader.close();
			if(releases.size() < 1) {
				caller.updaterNoUpdate(localVersion, localVersion);
				return;
			}
			final String remoteVersion = releases.get(0).asObject().get("name").asString().replace(projectName + " v", "");
			if(compareVersions(remoteVersion, localVersion)) {
				caller.updaterUpdateAvailable(localVersion, remoteVersion);
			}
			else {
				caller.updaterNoUpdate(localVersion, remoteVersion);
			}
		}
		catch(final Exception ex) {
			caller.updaterException(ex);
		}
	}
	
	/**
	 * Compares two versions.
	 * 
	 * @param versionTo The version you want to compare to.
	 * @param versionWith The version you want to compare with.
	 * 
	 * @return <b>true</b> If <b>versionTo</b> is inferior than <b>versionWith</b>.
	 * <br><b>false</b> If <b>versionTo</b> is superior or equals to <b>versionWith</b>.
	 */
	
	private static final boolean compareVersions(final String versionTo, final String versionWith) {
		return normalisedVersion(versionTo, ".", 4).compareTo(normalisedVersion(versionWith, ".", 4)) > 0;
	}
	
	/**
	 * Gets the formatted name of a version.
	 * <br>Used for the method <b>compareVersions(...)</b> of this class.
	 * 
	 * @param version The version you want to format.
	 * @param separator The separator between the numbers of this version.
	 * @param maxWidth The max width of the formatted version.
	 * 
	 * @return A string which the formatted version of your version.
	 * 
	 * @author Peter Lawrey.
	 */

	private static final String normalisedVersion(final String version, final String separator, final int maxWidth) {
		final StringBuilder stringBuilder = new StringBuilder();
		for(final String normalised : Pattern.compile(separator, Pattern.LITERAL).split(version)) {
			stringBuilder.append(String.format("%" + maxWidth + 's', normalised));
		}
		return stringBuilder.toString();
	}
	
	public interface BitbucketResultListener {
		
		/**
		 * When the updater starts.
		 */
		
		public void updaterStarted();
		
		/**
		 * When an Exception occurs.
		 * 
		 * @param ex The Exception.
		 */
		
		public void updaterException(final Exception ex);
		
		/**
		 * The response of the request.
		 * 
		 * @param response The response.
		 */
		
		public void updaterResponse(final String response);
		
		/**
		 * If an update is available.
		 * 
		 * @param localVersion The local version (used to create the updater).
		 * @param remoteVersion The remote version.
		 */
		
		public void updaterUpdateAvailable(final String localVersion, final String remoteVersion);
		
		/**
		 * If there is no update.
		 * 
		 * @param localVersion The local version (used to create the updater).
		 * @param remoteVersion The remote version.
		 */
		
		public void updaterNoUpdate(final String localVersion, final String remoteVersion);
		
	}
	
}