tehlers / gradle-duplicate-classes-check

A Gradle plugin that checks whether different artifacts in a configuration provide the same classes

Gradle - Check duplicate classes

This Gradle plugin checks whether different artifacts in a configuration provide the same classes. Since this leads to rather nasty bugs, you probably want to find these problems beforehand. A typical cause of such issues are artifacts that changed their maven group id but kept there packages like 'c3p0:c3p0' that has been renamed to 'com.mchange:c3p0'.

Usage

You can either use the new plugin mechanism introduced with Gradle 2.1

build.gradle

plugins {
  id 'net.idlestate.gradle-duplicate-classes-check' version '1.2.0'
}

or the 'classic' way

build.gradle

buildscript {
  repositories {
    maven {
      url 'https://plugins.gradle.org/m2/'
    }
  }

  dependencies {
    classpath 'gradle.plugin.net.idlestate:gradle-duplicate-classes-check:1.2.0'
  }
}

apply plugin: 'net.idlestate.gradle-duplicate-classes-check'

to apply the plugin to your project.

The check is performed by the task checkForDuplicateClasses that has been added as dependency to the task check.

Fail the build or just get a report

By default, this task fails the build if any duplicate files are found in the dependency JAR’s. You can change that and just get a report when you set ignoreFailures = true

build.gradle

plugins {
  id 'net.idlestate.gradle-duplicate-classes-check' version '1.2.0'
}

checkForDuplicateClasses {
    ignoreFailures = true
}

Define which files to include in comparison

By default, all dependencies are included in the comparison and the following files and directory content is excluded:

• directory names

• files in META-INF, and it’s subdirectories

• files in OSGI-INF, and it’s subdirectories

• module-info.class

• *.html

• *.htm

• *.txt

• *.doc

• README.*

• LICENSE

• NOTICE

To add more filters to the list you can use excludes(). It takes one or more regular expressions as parameter that is used to match against file name.

You can also specify explicitly which files to be compared with includes(). It also accepts one or more regular expressions as parameter. excludes take precedence when matching file names.

You can also use includes and excludes to filter for specific JAR files.

You can also use excludeModules or excludeModule to exclude a module based on its identifier. The former method expects a ModuleIdentifier and the latter is a convenience method that allows the module identifier to be specified as a string.

build.gradle

import org.gradle.api.internal.artifacts.DefaultModuleIdentifier

plugins {
  id 'net.idlestate.gradle-duplicate-classes-check' version '1.2.0'
}

checkForDuplicateClasses {
    // Exclude all jar files that has javax in their name
    excludes('(javax)*.(.jar)')

    // This will exclude *.rtf files from comparison
    excludes('.*(.rtf)^')

    // Will check for presence only for class files that has OnlyThese in their name
    includes('(OnlyThese).*(.class)^')

    // Exclude modules with the different variants
    excludeModules([DefaultModuleIdentifier.newId('group', 'name')])
    excludeModule('group:name')
}

Usage in multi-module projects

When you use this plugin in multi-module projects, and you have enabled parallel builds it is recommended to add dependsOn to checkForDuplicateClasses task. This will guarantee that task will execute after all dependencies have been generated.

build.gradle

plugins {
  id 'net.idlestate.gradle-duplicate-classes-check' version '1.2.0'
}

checkForDuplicateClasses {
    dependsOn 'jar'
}

License

LICENSE