lighty-java

Automatic Java Runtime Environment (JRE) management for Minecraft launchers with multi-distribution support.

Overview

lighty-java provides automated downloading, installation, and management of Java runtimes for Minecraft:

Automatic JRE Download - Download Java on-demand based on Minecraft version requirements
Multi-Distribution Support - Temurin, GraalVM, Zulu, and Liberica distributions
Cross-Platform - Windows, Linux, and macOS (x64 and ARM64)
Version Detection - Automatically detect required Java version for any Minecraft version
Progress Tracking - Real-time download and extraction progress via event system

Quick Start

[dependencies]
lighty-java = "0.8.6"

Basic Usage

use lighty_java::{JavaDistribution, jre_downloader};
use std::path::Path;

#[tokio::main]
async fn main() {
    let runtime_dir = Path::new("./runtimes");

    // Download Java 21 (Temurin distribution)
    let java_path = jre_downloader::jre_download(
        runtime_dir,
        &JavaDistribution::Temurin,
        &21,
        |current, total| {
            let percent = (current * 100) / total;
            println!("Download progress: {}%", percent);
        }
    ).await.unwrap();

    println!("Java installed at: {}", java_path.display());
}

Version Detection

use lighty_java::runtime::get_jre_version;

// Minecraft 1.20.4 requires Java 17
let required_version = get_jre_version("1.20.4");
println!("Minecraft 1.20.4 requires Java {}", required_version);  // 17

// Minecraft 1.16.5 requires Java 8
let required_version = get_jre_version("1.16.5");
println!("Minecraft 1.16.5 requires Java {}", required_version);  // 8

Java Distributions

Distribution

Provider

Supported Versions

Best For

Temurin (Recommended)

Eclipse Adoptium

8, 11, 17, 21

General use, maximum compatibility

GraalVM

Oracle

17, 21

Modern Minecraft (1.17+), maximum performance

Zulu

Azul Systems

8, 11, 17, 21

Enterprise environments, certified deployments

Liberica

BellSoft

8, 11, 17, 21

Resource-constrained systems, lightweight deployments

Platform Support

Platform

Architecture

Temurin

GraalVM

Zulu

Liberica

Windows

x64

✅

Windows

ARM64

✅

❌

✅

Linux

x64

✅

Linux

ARM64

✅

macOS

x64

✅

macOS

ARM64 (M1/M2)

✅

Complete Example

use lighty_java::{JavaDistribution, jre_downloader, runtime};
use std::path::Path;

#[tokio::main]
async fn main() {
    let runtime_dir = Path::new("./runtimes");
    let minecraft_version = "1.20.4";

    // 1. Detect required Java version
    let java_version = runtime::get_jre_version(minecraft_version);
    println!("Minecraft {} requires Java {}", minecraft_version, java_version);

    // 2. Check if Java is already installed
    let java_path = match jre_downloader::find_java_binary(
        runtime_dir,
        &JavaDistribution::Temurin,
        &java_version
    ).await {
        Ok(path) => {
            println!("Using existing Java at: {}", path.display());
            path
        }
        Err(_) => {
            // 3. Download and install Java
            println!("Downloading Java {}...", java_version);
            jre_downloader::jre_download(
                runtime_dir,
                &JavaDistribution::Temurin,
                &java_version,
                |current, total| {
                    let percent = (current * 100) / total;
                    print!("\rProgress: {}%", percent);
                }
            ).await.unwrap()
        }
    };

    // 4. Run Java process
    let mut java_runtime = runtime::JavaRuntime::new(&java_path);
    java_runtime.add_arg("-version");

    java_runtime.run(
        |line| println!("[OUT] {}", line),
        |line| eprintln!("[ERR] {}", line),
    ).await.unwrap();
}