WdesLaunchers

A custom Minecraft launcher written in Swing, targeting operators who want to ship their own branded launcher on top of Mojang's vanilla version catalogue — with optional operator-served mirrors for modded / custom versions.

What it does

• Vanilla versions via Mojang. Fetches the version_manifest_v2.json from piston-meta.mojang.com, per-version JSONs from the hash-addressed piston-meta URLs, client jars from piston-data.mojang.com, asset indexes from piston-meta, asset objects from resources.download.minecraft.net and libraries from libraries.minecraft.net. Supports both the legacy minecraftArguments flat-string format (≤ 1.12) and the arguments.{game,jvm} object format (1.13+).

• Operator mirror for modded or custom versions. Any versions published in <URL_DOWNLOAD_VERSIONS_BASE>/versions/versions.json are merged into Mojang's manifest and take precedence on id collision — so a custom 1.7.10 from your mirror shadows Mojang's vanilla one, and 1.7.10-forge10.13.4 shows up in the dropdown next to vanilla without any extra configuration. See Operator mirror layout.

• Offline survival. Every JSON fetched at runtime (manifest, per-version JSON, asset index) is written to <workingDir>/cache/ or <workingDir>/versions|assets/... before being handed to the parser. Once a version has been seen online at least once, the launcher can start and play that version fully offline.

• Yggdrasil-compatible auth. The login form talks to your own auth server configured via URL_AUTHENTIFICATION_SYSTEM in the operator config — Mojang credentials are never sent. A reference server implementation lives at wdesportes/minecraft.auth.server; anything else speaking the same Yggdrasil API contract (the /authserver/* endpoints) will work too.

• Per-server theming. The bottom-bar text links and social icons are defined in the operator config (links[] and socials{}) and only render the entries you define; the window background rotates through images fetched from a URL_FONDS_DOWNLOAD mirror, with a time-of-day folder convention (jour / soiree / nuit) and falls back to the bundled background if a folder is empty.

• Diagnostics built in. Every launcher boot prints:

  [ INFO ] [build] commit=<sha> branch=<name> built=<timestamp>
  

  (injected by git-commit-id-plugin into the jar) so a bug report always pins down the exact source tree.

• Post-mortem hints for known JVM / Minecraft crashes. When the game process exits, the launcher dumps exit code, full argv and the last lines of its stdout to the log. For the most common failures it also pops a French modal dialog pointing at the fix (e.g. the pre-1.8 launchwrapper URLClassLoader cast that blows up on Java 9+, or the GNOME ATK wrapper missing on Debian/Ubuntu OpenJDK 8).

Quick start

Requires Java 8+ to build (Java 8 still necessary to run pre-1.8 Minecraft versions because of the launchwrapper URLClassLoader cast).

git clone https://github.com/wdesportes/minecraft_launcher_wdes.git
cd minecraft_launcher_wdes
mvn clean package
java -jar target/wdes-launcher-2.0.0-jar-with-dependencies.jar

The assembly plugin bakes every dependency into the single jar, so no classpath juggling at runtime.

Run the tests with:

mvn test

and the minimal house-style checker with:

mvn checkstyle:check

Configuration

On startup the launcher fetches its configuration from

<URL_CONFIGS>/<UUID>.conf

where <URL_CONFIGS> is a hardcoded constant in LauncherConstants.java and <UUID> is passed by the bootstrap (currently 33a86c10-1e71-4e51-83b5-bdf218f29b97). The shape is:

{
  "nom": "Wdes",
  "version": "1.7.10",              // "auto-mc" = let the profile decide
  "width": 880,
  "height": 520,
  "URL_FONDS_DOWNLOAD": "http://example.com/fonds/",
  "PLACEHOLDER_LOGIN": "Utilisateur",
  "PLACEHOLDER_PASSD": "Mot de passe",
  "URL_AUTHENTIFICATION_SYSTEM": "https://example.com/minecraft-auth/",

  // Bottom-left text links. Omit entirely to hide all of them.
  "links": [
    { "url": "https://example.com",       "name": "Site",  "tooltip": "Home" },
    { "url": "https://blog.example.com",  "name": "Blog",  "tooltip": "Blog" }
  ],

  // Bottom-right social icons keyed by network id. Icons show in
  // right-to-left order; skipped keys leave no gap.
  "socials": {
    "twitter": { "url": "https://x.com/you",               "tooltip": "Twitter" },
    "youtube": { "url": "https://youtube.com/@you",        "tooltip": "YouTube" },
    "facebook":{ "url": "https://facebook.com/you",        "tooltip": "Facebook" },
    "steam":   { "url": "https://steamcommunity.com/id/you","tooltip": "Steam" }
  }
}

Operator mirror layout

URL_DOWNLOAD_VERSIONS_BASE is the root of your optional mirror. The launcher hits the following paths on demand:

Path	Purpose
versions/versions.json	List of modded / custom versions, merged into Mojang manifest. Omit if you only want vanilla.
versions/<id>/<id>.json	Per-version JSON for operator-owned ids (shadowed vanilla ids or mirror-only ids).
versions/<id>/<id>.jar	Jar fallback when the per-version JSON has no downloads.client.url.
indexes/<id>.json	Asset-index fallback when the per-version JSON has no assetIndex.url.

Nothing here is required for vanilla Mojang versions — those are fetched from piston-meta / piston-data. The mirror only matters for entries the operator publishes.

A typical versions/versions.json:

{
  "latest": {
    "release":  "1.7.10",
    "snapshot": "1.7.10"
  },
  "versions": [
    {
      "id": "1.7.10",
      "type": "release",
      "time":        "2014-05-14T19:29:23+02:00",
      "releaseTime": "2014-05-14T19:29:23+02:00"
    }
  ]
}

latest is merged per-key — anything you define here wins over Mojang; keys you omit fall through to Mojang's values. This is how you pin the launcher's default "latest release" to your supported server version.

Development

Modules

• fr.wdes.launcher.Wdes — main class, splash window.
• fr.wdes.Launcher — singleton, owns the JFrame, config, version manager, profile manager, SQLite cache (~/.wdeslaunchers/wdeslaunchers.db).
• fr.wdes.updater.* — version manifest parsing, download scheduling, local cache invalidation.
• fr.wdes.GameLauncher — builds the java -cp ... net.minecraft.client... process, evaluates arguments.game rules, monitors stdout, surfaces known crashes.
• fr.wdes.ui.* — Swing UI. fr.wdes.ui.lite.* holds the glassy painted controls (LiteTextField, LiteComboBox, LiteCheckBox, LiteButton, LogoLabel, …).

Style

.editorconfig and checkstyle.xml define the minimum house rules:

• Final newline, no trailing whitespace, no CRLF, no star / unused imports.
• new Integer(int) and friends banned (JDK 16+ removal).
• Lines capped at 300 chars.
• System.out.println / System.err.println discouraged — use fr.wdes.logger.

Severity is warning, so legacy files keep compiling. Run mvn checkstyle:check for a report.

Tests

JUnit 4, lightweight smoke tests around the non-UI bits:

• RemoteVersionListTest — manifest merge, operator override, path helpers, Gson round-trips of real Mojang & operator JSON.
• JObjectContainerTest — config shape including the live operator config.
• ProfileVersionResolutionTest — dropdown-pick precedence.
• LibraryArtifactPathTest — Maven coordinates including the 1.13+ four-part classifier layout.
• BuildInfoTest — git.properties resilience.

Build marker

Every mvn package embeds a git.properties generated by pl.project13.maven:git-commit-id-plugin. fr.wdes.BuildInfo reads it at startup; the first lines of the launcher log always tell you exactly which commit is running. If you see commit=unknown, the jar was built outside a git working tree.

Known caveats

• Pre-1.8 Minecraft on Java 9+. launchwrapper ≤ 1.11 casts ClassLoader.getSystemClassLoader() to URLClassLoader. That only works on Java 8. Set the profile's Executable Java field to a Java 8 install. The launcher detects this crash and pops a French dialog walking the user through the fix.
• Debian / Ubuntu OpenJDK 8. Ships /etc/java-8-openjdk/accessibility.properties referencing org.GNOME.Accessibility.AtkWrapper without installing it. The launcher detects the resulting AWTError and offers three remedies (JVM arg, apt package, sed the config file).
• Modern multiplayer service calls. The launcher currently passes -Dminecraft.api.env=local to silence the in-game Realms availability checker. That also short-circuits the services API, which is fine for offline / LAN play against offline-mode servers. Enabling Yggdrasil-backed online multiplayer would mean shipping authlib-injector as a -javaagent — straightforward if the operator has a full Yggdrasil implementation.

License

Spoutcraft Launcher heritage — most files carry the Spout License Version 1 header. See the individual file headers for terms.