asset-optimizer

A Gradle plugin for static asset optimization in Spring Boot / JVM web applications.

Minifies CSS, JavaScript, and HTML. Optimizes PNG, JPEG, and SVG files. Converts images to WebP. Uses esbuild, oxipng, and cwebp with zero runtime dependencies — native binaries are bundled inside the plugin JAR.

Quick Start

Apply the plugin and place your assets under src/main/resources/static/:

./gradlew build

All supported file types are automatically optimized and included in the output JAR.

Features

• CSS minification via esbuild (**/*.css)
• JavaScript minification via esbuild (**/*.js)
• HTML minification with Thymeleaf support (**/*.html) — pure Java, no native binary
• PNG lossless optimization via oxipng (**/*.png)
• JPEG metadata stripping (**/*.jpg, **/*.jpeg) — pure Java
• SVG optimization — removes comments, metadata, empty groups (**/*.svg) — pure Java
• WebP conversion via cwebp (converts PNG, JPEG to WebP)
• Automatic src/main/resources/static/ scanning
• Hooks into processResources — no extra task needed
• Platform-specific native binary bundling

Configuration

assetOptimizer {
    sourceDirs = files("src/main/resources/static")
    outputDir = layout.buildDirectory.dir("asset-optimizer")
}

Tasks

Task	Description	Input
minifyCss	Minifies CSS files	**/*.css
minifyJs	Minifies JavaScript files	**/*.js
minifyHtml	Minifies HTML files	**/*.html
optimizePng	Lossless PNG optimization	**/*.png
optimizeSvg	SVG optimization	**/*.svg
optimizeJpeg	JPEG metadata stripping	**/*.jpg, **/*.jpeg
convertWebp	Converts PNG/JPEG to WebP	**/*.png, **/*.jpg

All tasks run automatically as dependencies of processResources.

How It Works

1. At runtime, the plugin detects the current OS and architecture, extracts the matching native binary (esbuild, oxipng, or cwebp) to a temp directory, and uses it for optimization.
2. The processResources task is extended with all optimization tasks — no extra configuration required for basic use.
3. HTML, SVG, and JPEG optimizations use pure Java implementations — no native binaries required for these.

Requirements

• Java 17+

License

MIT — see LICENSE for details.