Tested on Java LTS versions from 11 to 21.

Tested on Gradle versions from 7.0 to 8.13.

name.remal.merge-resources plugin

Usage:

plugins {
    id 'name.remal.merge-resources' version '5.0.1'
}

 

This plugin configures all AbstractCopyTask tasks to merge files with the same RelativePath.

The main use cases are:

• building fat JARs
• generating some files via annotation processors and configuring the same files manually

Configuration

mergeResources {
  metaInfServices {
    enabled = false // To disable merging `META-INF/services/*`
  }
  packageInfo {
    enabled = false // To disable merging `META-INF/services/*`
  }
  metaInfServices {
    enabled = false // To disable merging `**/package-info.class`
  }
  moduleInfo {
    enabled = false // To disable merging `**/module-info.class`
  }
  springFactories {
    enabled = false // To disable merging `META-INF/spring.factories`
  }
  springImports {
    enabled = false // To disable merging `META-INF/spring/*.imports`
  }
  log4j2PluginsMerger {
    enabled = false // To disable merging `META-INF/org/apache/logging/log4j/core/config/plugins/Log4j2Plugins.dat`
  }

  // To merge all `*.jar` files with the same relative path:
  addResourceMerger('**/*.jar') { RelativePath relativePath, Collection<Path> paths, OutputStream outputStream ->
    outputStream.write(new byte[0])
  }

  // To merge all `*.text` files with the same relative path:
  addTextResourceMerger('**/*.jar', 'US-ASCII') { RelativePath relativePath, Collection<Path> paths, PrintWriter writer ->
    writer.println('test')
  }
  addTextResourceMerger('**/*.jar' /* UTF-8 is default charset */) { RelativePath relativePath, Collection<Path> paths, PrintWriter writer ->
    writer.println('test')
  }
}

Built-in mergers

META-INF/services/*

Excluding:

• META-INF/services/org.codehaus.groovy.runtime.ExtensionModule

These files are used for Java's java.util.ServiceLoader.

When these files are merged, all comments and duplications are removed.

**/package-info.class

The file with the biggest number of package annotations is taken.

For the other files, there is a check that validates their package annotations present in the result file.

**/module-info.class

Different sections of module-info are merged.

It's required that all merged files have the same module name.

META-INF/spring.factories

See org.springframework.core.io.support.SpringFactoriesLoader.

META-INF/spring/*.imports

See META-INF/spring/org.springframework.boot.autoconfigure.AutoConfiguration.imports files.

See org.springframework.boot.context.annotation.ImportCandidates.

META-INF/org/apache/logging/log4j/core/config/plugins/Log4j2Plugins.dat

See documentation about Log4j plugin descriptor.

Migration guide

Version 4.* to 5.*

The minimum Java version is 11 (from 8). The minimum Gradle version is 7.0 (from 6.0).

Version 3.* to 4.*

Path is used for mergers instead of File.

Version 2.* to 3.*

Resource merges do not return InputStream anymore. OutputStream is provided as a parameter instead for mergeResources.addResourceMerger(). PrintWriter is provided as a parameter instead for mergeResources.addTextResourceMerger().

Version 1.* to 2.*

The plugin was fully rewritten. There were no intentions to keep backward compatibility.