Build.gradle: Difference between revisions

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=External=
=External=
* https://docs.gradle.org/current/userguide/writing_build_scripts.html
* https://docs.gradle.org/current/userguide/writing_build_scripts.html


=Internal=
=Internal=
 
* [[Gradle_Concepts#Configuration_Scripts_and_Core_Types|Gradle Concepts]]
* [[Gradle Configuration#build.gradle|Gradle Configuration]]
* [[Gradle Project#Overview|Project]]
* [[Gradle_Concepts#build.gradle|Gradle Concepts]]


=Overview=
=Overview=
 
build.gradle is referred to as an Gradle build script. It is the script interface to a [[Gradle_Project#Project_API_and_build.gradle_DSL|Project instance]].
The project-level configuration script that contains task configuration for the current project, written in the Gradle's DSL. It tells Gradle what to build. The build script may contain any Groovy language element, including:
 
* <tt>println</tt>
* [[#Variables|variable declarations]]
* [[Gradle_Concepts#Plugin|plugin declarations]]
* [[#Repositories|repositories]]
 
To make build scripts more concise, Gradle automatically adds the set of default Gradle import statements to the script.


=Example=
=Example=
<syntaxhighlight lang='groovy'>


<syntaxhighlight lang='groovy'>
apply plugin: 'java'
apply plugin: 'java'


group = "io.novaordis.playground.gradle"
// name comes from the directory name or it can be changed in settings.gradle
version = "1.0"
group = "playground.example"
sourceCompatibility = 1.8
version = "0.1.0"
targetCompatibility = 1.8
description = "A Gradle example project"


repositories {
repositories {
    mavenLocal()
     mavenCentral()
     mavenCentral()
}
configurations.all {
    resolutionStrategy.cacheChangingModulesFor 3600, 'seconds'
}
}


Line 44: Line 31:
configurations {
configurations {
     testImplementation.exclude group: 'com.example'
     testImplementation.exclude group: 'com.example'
}
configurations.all {
    resolutionStrategy.cacheChangingModulesFor 3600, 'seconds'
}
}


Line 66: Line 57:
</syntaxhighlight>
</syntaxhighlight>


=Variables=
=Code=
 
There are two kinds of variables that can be declared in a build script: local variables and extra properties:
 
==Local Variables==
 
Local variables, which are a feature of the underlying Groovy language, are declared with the "def" keyword. They are only visible in the scope where they have been declared.
 
<syntaxhighlight lang='groovy'>
def myVariable = "something"
...
println myVariable
</syntaxhighlight>
 
==Extra Properties==
 
[[Gradle_Properties#Extra_Properties|Extra properties]] can be declared as follows:


The build script may include general-purpose Java and Groovy code:
<syntaxhighlight lang='groovy'>
<syntaxhighlight lang='groovy'>
...
ext {
    log4jVersion = "2.1.7"
    emailNotification = "build@example.com"
}
...
</syntaxhighlight>


=DSL=
class Experimental {


The following elements are part of [https://docs.gradle.org/current/dsl/org.gradle.api.Project.html Project] API.
    private String name;


==configurations.all==
    Experimental(String name) {


Applies enclosed to all [[Gradle_Concepts#Dependency_Configuration|configurations]].
        this.name = name;
 
<syntaxhighlight lang='groovy'>
configurations.all {
    resolutionStrategy.cacheDynamicVersionsFor 10, 'minutes'
}
</syntaxhighlight>
 
Alternative:
 
<syntaxhighlight lang='groovy'>
configurations.all {
    resolutionStrategy {
        cacheDynamicVersionsFor 10, 'minutes'
     }
     }
}
</syntaxhighlight>
===Configuration===
====resolutionStrategy====


{{External|https://docs.gradle.org/current/dsl/org.gradle.api.artifacts.ResolutionStrategy.html}}
     @Override
 
     public String toString() {
=====cacheDynamicVersionsFor=====
         return name;
 
Configures [[Gradle_Concepts#Dynamic_Version|dynamic version]] caching threshold.
 
<syntaxhighlight lang='groovy'>
resolutionStrategy.cacheDynamicVersionsFor 10, 'minutes'
</syntaxhighlight>
 
=====cacheChangingModulesFor=====
 
==configurations==
 
<syntaxhighlight lang='groovy'>
configurations {
     testCompile.exclude group: 'io.example'
}
</syntaxhighlight>
 
==buildscript==
 
Used when [[Gradle Concepts#External_Plugins|external plugins]] need to be downloaded.
 
<syntaxhighlight lang='groovy'>
buildscript {
     repositories {
         maven { url 'https://plugins.gradle.org/m2/' }
     }
     }
  dependencies {
    classpath 'com.netflix.nebula:gradle-ospackage-plugin:4.3.0'
  }
}
</syntaxhighlight>
==<span id='Repositories'></span>repositories==
{{External|https://docs.gradle.org/current/userguide/declaring_repositories.html}}
[[Gradle Concepts#Repository|Repositories]] are declared in a 'repositories' block:
<syntaxhighlight lang='groovy'>
repositories {
    ...
}
}
</syntaxhighlight>


Multiple repositories can be declared in the same block. Syntax examples are available for [[Gradle_Concepts#Custom_Maven_Repository|custom Maven repositories]], [[Gradle_Concepts#flatDir|directory-based repositories]], [[Gradle_Concepts#Maven_Central|Maven Central]], etc. The most common setting is declaring that our dependencies are available in Maven Central:
def experimental = new Experimental("blue");


<syntaxhighlight lang='groovy'>
task test {
repositories {
     doLast {
    mavenCentral()
         println experimental
}
</syntaxhighlight>
 
==dependencies==
 
A DSL element that declares the [[Gradle_Concepts#Dependency|dependencies]] of the [[Gradle_Concepts#Module|module]]. The block lists [[Gradle_Concepts#Dependency_Configuration|dependency configurations]] known to the project, followed by list of dependencies.
 
<syntaxhighlight lang='groovy'>
dependencies {
     implementation 'org.slf4j:slf4j-api:1.7.12'
    api 'com.google.guava:guava:23.0'
    ...
}
</syntaxhighlight>
 
Note that the declared dependencies must be available in a declared repository, so [[#repositories|repositories must be declared]].
 
Dependencies can also be declared without a version, and [[Gradle_Concepts#Dependency_Constraint|dependency constraints]] can be used to manage the version, including the transitive versions.
 
<syntaxhighlight lang='groovy'>
dependencies {
    implementation 'org.slf4j:slf4j-api'
    constraints {
         implementation 'org.slf4j:slf4j-api:1.7.12'
     }
     }
}
}
</syntaxhighlight>
</syntaxhighlight>
=Custom Tasks=
{{Internal|Gradle Custom Task#Overview|Custom Tasks}}

Latest revision as of 22:10, 11 October 2020

External

Internal

Overview

build.gradle is referred to as an Gradle build script. It is the script interface to a Project instance.

Example

apply plugin: 'java'

// name comes from the directory name or it can be changed in settings.gradle
group = "playground.example"
version = "0.1.0"
description = "A Gradle example project"

repositories {
    mavenLocal()
    mavenCentral()
}

dependencies {
    implementation 'org.slf4j:slf4j-api:1.7.12'
    testImplementation 'junit:junit:4.+'
}

configurations {
    testImplementation.exclude group: 'com.example'
}

configurations.all {
    resolutionStrategy.cacheChangingModulesFor 3600, 'seconds'
}

compileJava {
    options.compilerArgs += ['-Xlint']
}

javadoc {
    options.charSet = 'UTF-8'
}

task runMain(type: JavaExec) {
    classpath = sourceSets.main.runtimeClasspath
    main = "io.novaordis.playground.gradle.java.Main"
}

Comments

// This is a comment

Code

The build script may include general-purpose Java and Groovy code: 

class Experimental {

    private String name;

    Experimental(String name) {

        this.name = name;
    }

    @Override
    public String toString() {
        return name;
    }
}

def experimental = new Experimental("blue");

task test {
    doLast {
        println experimental
    }
}
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