Gradle is build automation evolved. Gradle can automate the building, testing, publishing, deployment and more of software packages or other types of projects such as generated static websites, generated documentation or indeed anything else.
Gradle combines the power and flexibility of Ant with the dependency management and conventions of Maven into a more effective way to build. Powered by a Groovy DSL and packed with innovation, Gradle provides a declarative way to describe all kinds of builds through sensible defaults. Gradle is quickly becoming the build system of choice for many open source projects, leading edge enterprises and legacy automation challenges.
Of course, you can download and install Gradle from http://www.gradle.org/downloads.
If you are using Unix based system such as Linux, Mac OSX and etc.. I recommend you to install from GVM. GVM is a tool for managing parallel Versions of multiple Software Development Kits on most Unix based systems like RVM and rbenv for Ruby. You also can install Groovy.
Open your shell terminal and enter the following command:
$ curl -s get.gvmtool.net | bash
Open a new shell or enter the command:
$ source "~/.gvm/bin/gvm-init.sh"
Install the current Gradle version:
$ gvm install gradle
For the detail of usage, please refer to http://gvmtool.net/.
Create a file called build.gradle. This is a build script.
task hello {
doLast {
println 'Hello world!'
}
}
Execute the build script with gradle -q hello:
$ gradle -q hello
Hello world!
There are some basic concepts that you shold know.
As the script executes, it configures an object of a particular type. For example, as a build script executes, it configures an object of type Project. There is a one-to-one relationship between a Project and a build.gradle file.
A project is essentially a collection of Task objects. Each task performs some basic piece of work, such as compiling classes, or running unit tests
The following table shows the delegate for each type of Gradle script.
| Type of script | Delegates to instance of |
|---|---|
| Build script | Project |
| Init script | Gradle |
| Settings script | Settings |
The properties and methods of the delegate object are available for you to use in the script.
This interface defines a number of properties and methods which you can use in the script.
A build script is made up of zero or more statements and script blocks. Statements can include method calls, property assignments, and local variable definitions.
USAGE: gradle [option...] [task...]
There are some help tasks you should know, which can help you to write build script and find problem.
See all tasks runnable from a project by typing:
$ gradle <project-path>:tasks
And you can see all tasks you defined and help tasks as well.
For the root project, you can just type gradle tasks
See the sub-projects of a project by typing:
$ gradle <project-path>:projects
See the properties of a project by typing:
$ gradle <project-path>:properties
It displays a log of properties like:
See the dependencies declared of a project by typing:
$ gradle <project-path>:dependencies
Everything in Gradle sits on top of two basic concepts: projects and tasks. Every Gradle build is made up of one or more projects. Each project is made up of one or more tasks. A task represents some atomic piece of work which a build performs.
build.gradle
task hello {
doLast {
println 'Hello world!'
}
}
There is another easy way to define a task:
task hello << {
println 'Hello world!'
}
build.gradle
task hello << {
String name = 'jeoygin'
println "Hello " + name.toUpperCase()
}
Output of gradle -q hello
$ gradle -q hello
Hello JEOYGIN
or more complicated.
task count << {
4.times {print "${it + 1} "}
}
Output of gradle -q count
$ gradle -q count
1 2 3 4
The value of variable can be read in a string by $var or ${var}.
build.gradle
task taskX(dependsOn: 'taskY') << {
println 'taskX'
}
task taskY << {
println 'taskY'
}
Output of gradle -q taskX
$ gradle -q taskX
taskY
taskX
build.gradle
4.times { counter ->
task "task$counter" << {
println "I'm task number $counter"
}
}
Part of output of gradle -q tasks
$ gradle -q tasks
Other tasks
-----------
task0
task1
task2
task3
Output of gradle -q task0
$ gradle -q task0
I'm task number 1
build.gradle
4.times { counter ->
task "task$counter" << {
println "I'm task number $counter"
}
}
task0.dependsOn task2, task3
Output of gradl -q task0
$ gradle -q task0
I'm task number 2
I'm task number 3
I'm task number 0
Or add behavior to an existing task.
build.gradle
task hello << {
println 'Hello Earth'
}
hello.doFirst {
println 'Hello Venus'
}
hello.doLast {
println 'Hello Mars'
}
hello << {
println 'Hello Jupiter'
}
Output of gradle -q hello
$ gradle -q hello
Hello Venus
Hello Earth
Hello Mars
Hello Jupiter
You can add your own properties to a task. To add a property named myProperty, set ext.myProperty to an initial value.
build.gradle
task test {
ext.extraProperty = "extra"
}
task printExtraProperties << {
println test.extraProperty
}
Output of gradle -q printExtraProperties
$ gradle -q printExtraProperties
extra
build.gradle
task hello {
sayHello('Jeoygin')
}
String sayHello(String name) {
println "Hello $name"
}
Output of gradle -q hello
$ gradle -q hello
Hello Jeoygin
build.gradle
defaultTasks 'clean', 'run'
task clean << {
println 'Default Cleaning!'
}
task run << {
println 'Default Running!'
}
task other << {
println "I'm not a default task!"
}
Output of gradle -q
$ gradle -q
Default Cleaning!
Default Running!
build.gradle
task distribution << {
println "Build the project with version=$version"
}
task release(dependsOn: 'distribution') << {
println 'Release the project'
}
gradle.taskGraph.whenReady {taskGraph ->
if (taskGraph.hasTask(release)) {
version = '1.0'
} else {
version = '1.0-SNAPSHOT'
}
}
Output of gradle -q distribution
$ gradle -q distribution
Build the project with version=1.0-SNAPSHOT
Output of gradle -q release
$ gradle -q release
Build the project with version=1.0
Release the project