JMCCC

A powerful open-source library for launching and downloading Minecraft.

License

JMCCC is licensed under the MIT license.

Features

• Launches all versions of Minecraft
• Scalable authentication
  • Supports Microsoft Account/Mojang Account/Offline, and can be extended
• Downloads all versions of Minecraft
  • Supports Forge/Liteloader/Fabric/Quilt
    • Supports Liteloader snapshots
    • Supports Fabric/Quilt in Minecraft snapshots
  • Customizable download source
  • Asynchronous task system
  • Supports BIO/NIO
    • Can work on top of Apache HttpAsyncClient or JDK
  • Supports caching
    • Can work on top of Ehcache or javax.cache
    • Different strategies for different files
• Mojang API supports
  • Game profiles lookup
  • Fetches/Uploads textures
  • Fetches account information
  • Fetches name history
  • Blocked servers checking

Quick Start

Dependencies

JMCCC RELEASE version has been uploaded to MAVEN CENTRAL:

https://repo1.maven.org/maven2/

If you do need the snapshot repository:

https://s01.oss.sonatype.org/content/repositories/snapshots/

Launching Minecraft

MinecraftDirectory dir = new MinecraftDirectory("/home/user/.minecraft");
Launcher launcher = LauncherBuilder.buildDefault();
launcher.launch(new LaunchOption("1.19.3", MicrosoftAuthenticator.login(it -> System.out.println(it.message)), dir));

You can use Microsoft Account with MicrosoftAuthenticator.login(it -> System.out.println(it.message)), also you can use YggdrasilAuthenticator.password("<email>", "<password>") with Mojang Account or new OfflineAuthenticator("<username>") if you want to use offline authentication.

Downloading Minecraft

MinecraftDirectory dir = new MinecraftDirectory("/home/user/.minecraft");
MinecraftDownloader downloader = MinecraftDownloaderBuilder.buildDefault();
downloader.downloadIncrementally(dir, "1.19.3", new CallbackAdapter<Version>() {
	
	@Override
	public void failed(Throwable e) {
		// when the task fails
	}
	
	@Override
	public void done(Version result) {
		// when the task finishes
	}
	
	@Override
	public void cancelled() {
		// when the task cancels
	}
	
	@Override
	public <R> DownloadCallback<R> taskStart(DownloadTask<R> task) {
		// when a new sub download task starts
		// return a DownloadCallback to listen the status of the task
		return new CallbackAdapter<R>() {

			@Override
			public void done(R result) {
				// when the sub download task finishes
			}

			@Override
			public void failed(Throwable e) {
				// when the sub download task fails
			}

			@Override
			public void cancelled() {
				// when the sub download task cancels
			}

			@Override
			public void updateProgress(long done, long total) {
				// when the progress of the sub download task has updated
			}

			@Override
			public void retry(Throwable e, int current, int max) {
				// when the sub download task fails, and the downloader decides to retry the task
				// in this case, failed() won't be called
			}
		};
	}
});

You can pass a null callback if you don't want to monitor the whole task. You can also return null in taskStart() if you don't want to monitor sub tasks.

Don't forget to shutdown the downloader when you are no longer going to use it.

downloader.shutdown();

Downloading Forge/Liteloader/Fabric/Quilt

MinecraftDirectory dir = new MinecraftDirectory("/home/user/.minecraft");
ForgeDownloadProvider forgeProvider = new ForgeDownloadProvider();
LiteloaderDownloadProvider liteloaderProvider = new LiteloaderDownloadProvider();
MinecraftDownloader downloader = MinecraftDownloaderBuilder.create()
	.providerChain(DownloadProviderChain.create()
		.addProvider(forgeProvider)
		.addProvider(liteloaderProvider))
	.build();

downloader.downloadIncrementally(dir, "1.19.3-forge-44.1.7", new CallbackAdapter<Version>() {...});
downloader.downloadIncrementally(dir, "1.12.2-LiteLoader1.12.2", new CallbackAdapter<Version>() {...});
downloader.downloadIncrementally(dir, "fabric-loader-0.14.13-1.19.3", new CallbackAdapter<Version>() {...});
downloader.downloadIncrementally(dir, "quilt-loader-0.17.11-1.19.3", new CallbackAdapter<Version>() {...});
downloader.download(forgeProvider.forgeVersionList(), new CallbackAdapter<ForgeVersionList>() {...});
downloader.download(liteloaderProvider.liteloaderVersionList(), new CallbackAdapter<LiteloaderVersionList>() {...});

FML options

JMCCC won't add fml options (such as -Dfml.ignoreInvalidMinecraftCertificates=true and -Dfml.ignorePatchDiscrepancies=true) to the command line automatically. If you have problems launching forge, you may need to add these arguments manually. These arguments are already defined in class ExtraArgumentsTemplates.

option.extraJvmArguments().add(ExtraArgumentsTemplates.FML_IGNORE_INVALID_MINECRAFT_CERTIFICATES);
option.extraJvmArguments().add(ExtraArgumentsTemplates.FML_IGNORE_PATCH_DISCREPANCISE);