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| Date post: | 20-Jan-2017 |
| Category: |
Technology |
| Upload: | aestas-it |
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About me02
Andrey AdamovichBio: Developer, coach, speaker, author
Company: Aestas/IT (http://aestasit.com)
Email: [email protected]
Linkedin: http://www.linkedin.com/in/andreyadamovich
Lanyrd: http://lanyrd.com/profile/andreyadamovich
GitHub: https://github.com/aadamovich
SO: http://stackoverflow.com/users/162792/andreyadamovich
Twitter: @codingandrey, @aestasit
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What is Groovy?Groovy is a dynamic language for the JVM.
It is built upon features of Java langauge, but adds more goodies
derived from languages like Python, Ruby and SmallTalk.
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History2003: inception
2007: 1.0 released
2012: 2.0 released
2016: 3.0 planned
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Who is using Groovy?
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InstallingGroovy
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Groovy consoleAfter Groovy is installed you can launch a groovyConsole :•
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Groovy shellor groovySh if you prefer commandline:•
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Languagebasics
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Hello, Groovy!println "Hello, World!"01.
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Variablesdef title = "Groovy is cool!"
def year = 2015
def rate = 0.702
String name = "John"
def isExecuted = true
test = new Object()
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TypesAll Java types are available:
int , long , double , float , boolean , char , byte , short ,
String , Date , Calendar , File ,...
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Groovy = Java + Groovy extensionsGroovy is built on top of Java.
All classes that are part of Java can be used in Groovy.
Groovy adds additional functionality to some Java classes.
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StringsThis is Java's String API:
http://docs.oracle.com/javase/8/docs/api/java/lang/String.html.
This is Groovy's extensions to String API: http://docs.groovy
lang.org/latest/html/groovyjdk/java/lang/String.html.
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String interpolationdef name = "John"
def greeting = "Hello, $name"
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Multiline stringsWithout string interpolation:
def POEM = '''Two households, both alike in dignity,
In fair Verona, where we lay our scene,
From ancient grudge break to new mutiny,
Where civil blood makes civil hands unclean.'''
```
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Multiline stringsWith string interpolation:
def city = 'Verona'
def POEM2 = """Two households, both alike in dignity,
In fair ${city}, where we lay our scene,
From ancient grudge break to new mutiny,
Where civil blood makes civil hands unclean."""
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OperatorsNumbers: a + b , a ‐ b , a * b , a ** b , a / b , a % b ,
a++ , ++a , a‐‐ , ‐‐a , ‐a , +a
Bits: a | b , a & b , a ^ b , a << b , a >> b
Booleans: a || b , a && b , a ^^ b , ~a
Comparison: a == b , a != b , a <=> b , a > b , a >= b , a <
b , a <= b
Regular expressions: str =~ pattern , str ==~ pattern
Objects: obj?.child , obj*.children , obj.@field ,
obj.&method
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ConditionalsNo surprises:
if (condition) {
... some code ...
} else {
... some code ...
}
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Groovy truthAny expression can be mapped to a boolean value according to
Groovy's truth:
0 is false , all other numbers are true
empty String is false, all other String s are true
empty collection is false , nonempty collections are true
null is false , all other objects are true
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Elvis operator (?:)Shorthand for if statements:
def result = condition ? true_result : false_result
or in short:
def result = true_result ?: false_result
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Elvis operator (?:)This one:
def userName = user.name ? user.name : "none"
is the same as this one:
def userName = user.name ?: "none"
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Safe navigation operator (?.)If you have nested object structure that may have missing
components, then safe navigation operator can save you from
NullPointerException s.
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Safe navigation operator (?.)For example, this expression is risky:
def cityName = person.address.city.name01.
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Safe navigation operator (?.)But this one will return null in case at least one of the expression
components is null :
def cityName = person?.address?.city?.name01.
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Functionsdef calculate(int a, String str) {
return a + str.length
}
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Function's resultIf return statement is absent then last expression value is considered
the result of a function:
def calculate(int a, String str) { a + str.length }01.
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CollectionsLists:
def numbers = [5, 32, 21, 22]
println numbers[0]
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CollectionsMaps:
def chars = [a: 11, b: 2, c: 73]
println chars['b']
println chars.c
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Collection typesYou can define collection type you want to have:
def numbers = [1, 2, 3, 3, 4] as Set01.
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Useful typesList the default collection type list of elements stored in insertion
order.
Set a collection of unique elements stored in no particular order.
SortedSet a collection of unique elements stored in sorted order.
LinkedHashSet a collection of unique elements stored in insertion
order.
Map a collection of key/value pairs stored in no particular order.
TreeMap a map stored in order sorted by the key.
LinkedHashMap a map stored in insertion order.
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LoopsNo surprises:
def x = 0
for (i in 0..9) {
x += i
}
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Loopsdef numbers = [1, 2, 3, 3, 4] as Set
for (n in numbers) {
println n
}
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Loopsdef x = 0
def y = 5
while ( y‐‐ > 0 ) {
x++
}
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ClosuresClosure in Groovy is an anonymous function that can be called and
passed to other functions.
def square = { it * it }
println square(9)
def squares = [ 1, 2, 3, 4 ].collect(square)
println squares
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IteratorsGroovy's collection API is coming with many closurebased methods
for collection iteration:
numbers.each { n ‐>
prinln n
}
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Finders... and collection searching and filtering:
println numbers.findAll { it > 5 }01.
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Collection APIJava API:
http://docs.oracle.com/javase/8/docs/api/java/util/Collection.html
http://docs.oracle.com/javase/8/docs/api/java/util/List.html
http://docs.oracle.com/javase/8/docs/api/java/util/Map.html
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Collection APIGroovy API:
http://docs.groovylang.org/latest/html/groovy
jdk/java/util/Collection.html
http://docs.groovylang.org/latest/html/groovyjdk/java/util/List.html
http://docs.groovylang.org/latest/html/groovyjdk/java/util/Set.html
http://docs.groovylang.org/latest/html/groovyjdk/java/util/Map.html
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Using closures to define a DSLClosures can be used to "wrap" around some code.
def safeResource(Closure closure) {
def resource = new ExpensiveResource()
try {
resource.open()
closure(resource)
} finally {
resource?.close()
}
}
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Using closures to define a DSLsafeResource { it ‐>
it.writeData("hello world!")
}
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Regular expressionsdef input = "The Groovy Cook Book contains Groovy recipes"
if (input =~ /^.*?Groovy.*$/) {
println "Found Groovy"
}
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Group matchingdef input = "The Groovy Cook Book contains Groovy recipes"
def matcher = input =~ /^.*?(Groovy).*$/
println matcher[0][1]
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String splittingdef input = "name;address;city"
def fields = input.split(';')
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Search and replacedef input = "The Groovy Cook Book contains Groovy recipes"
input.replaceAll('.oo..', 'DROOPY')
println input.replaceAll(/.oo../) { match ‐>
match.toUpperCase()
}
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FilesFile object represents abstract path of a file or directory e.g.:
def configFile = new File('config.xml')
def dataDir = new File('data')
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File APIJava API: http://docs.oracle.com/javase/8/docs/api/java/io/File.html
Groovy extensions: http://docs.groovylang.org/latest/html/groovy
jdk/java/io/File.html
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Reading from a fileString textContent = file.text
byte[] binaryContent = file.bytes
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Reading from a filedef lines = file.readLines()
lines.each { String line ‐>
println line
}
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Reading from a filefile.eachByte { int byte ‐>
// do something with byte
}
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Writing to a filefile.text = '''What's in a name? That which we call a rose
By any other name would smell as sweet.'''
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Writing to a filefile << "What's in a name? That which we call a rose\n"
file << "By any other name would smell as sweet."
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Writing to a filefile.bytes = [ 65, 66, 67, 68 ] as byte[]01.
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Useful utilitiesJsonSlurper
JsonBuilder
XmlSlurper
MarkupBuilder
HttpBuilder
ConfigSlurper
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Ecosystem56
Grape57
SDKMAN!58
Automation59
Gradle60
Projects and tasksMain concepts in Gradle are Project and Task.
Project consists of a set of tasks and settings.
Task is a logical action performing certain things within project context.
It has access to project information and settings.
Tasks may depend on other tasks.
Project can consist of several subprojects.
In this case, it is called multiproject build.
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Gradle's DSLGradle's build language is a Groovybased DSL that is built around
Project and Task API.
Extensive documentation can be found here:
http://gradle.org/docs/current/dsl/index.html.
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Hello, Gradle!build.gradle :
task hello << {
println 'Hello, World'
}
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Hello, Gradle!Console output:
>gradle hello
:hello
Hello, World!
BUILD SUCCESSFUL
Total time: 0.401 secs
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Task configuration & executionbuild.gradle :
task hello
ext.message = "What's up?"
hello {
println "Configuring hello task."
ext.message = 'Hello, World!'
}
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Task configuration & executionhello << {
println message
}
hello << {
println project.message
}
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Task configuration & executionConsole output:
>gradle hello
Configuring hello task.
:hello
Hello, World!
What's up?
BUILD SUCCESSFUL
Total time: 0.058 secs
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Gradle is Groovy, Groovy is JavaJava:
import java.io.File;
...
String parentDir = new File('test.txt')
.getAbsoluteFile()
.getParentPath();
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Gradle is Groovy, Groovy is JavaGroovy:
def parentDir = new File('test.txt')
.absoluteFile
.parentPath
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Gradle is Groovy, Groovy is JavaGradle:
parentDir = file('test.txt').absoluteFile.parentPath01.
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Task dependenciesbuild.gradle :
task hello << {
print 'Hello, '
}
task world(dependsOn: hello) << {
println 'World!'
}
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Task dependenciesConsole output:
>gradle ‐q hello world
Hello, World!
>gradle ‐q world
Hello, World!
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Dynamic tasks4.times { counter ‐>
task "task$counter" << {
println "I'm task number $counter"
}
}
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Task rulestasks.addRule("Pattern: ping<ID>") { String taskName ‐>
if (taskName.startsWith("ping")) {
task(taskName) << {
println "Pinging: " + (taskName ‐ 'ping')
}
}
}
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Task rulestask groupPing {
dependsOn pingServer1, pingServer2
}
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Failing the buildTo fail the build you can just throw an exception with descriptive
message:
throw new GradleException("Failed because of ....")01.
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Functions and variablesYou can define local variables and functions inside your build script
like you would do in Groovy ( def ).
Those variables and functions will only be visible within that script.
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Default tasksIf you run Gradle command with no tasks specified, then it will fall back
to the list of default tasks if they are defined:
defaultTasks 'build'01.
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Task graphgradle.taskGraph.whenReady { taskGraph ‐>
if (taskGraph.hasTask(release)) {
version = '1.0'
} else {
version = '1.0‐SNAPSHOT'
}
}
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Task graphgradle.taskGraph.beforeTask { Task task ‐>
println "executing $task ..."
}
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Task graphgradle.taskGraph.afterTask { Task task, TaskState state ‐>
if (state.failure) {
println "FAILED"
} else {
println "done"
}
}
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WebDevelopment
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Grails83
Ratpack84
Testing85
Spock86
Cucumber87
Geb88
DesktopApplication89
Griffon90
Groovyshines atDSLs!
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Let's build aDSL!
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Readingmaterial
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Groovy 2 Cookbook
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Groovy in action
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Groovy for DSLs
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Making Java Groovy
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Programming Groovy 2
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Building & testing with Gradle
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Gradle: effective implementation guide
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Q & A101
Let the forcebe with you!
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Thank you!103
