Introduction to the Groovy Programming Language

1. Groovy
André Faria Gomes

2. O que é Groovy
Groovy é uma linguagem ágil dinâmica
para a plataforma Java com muitas
funcionalidades inspiradas de
linguagens como Python, Ruby e
Smalltalk, disponibilizando tais
funcionalidades para os
desenvolvedores Java em uma sintaxe
muito semelhante a Java.

3. Mapa do Groovy

4. Comparado
Groovy
new File('.').eachFileRecurse { println it }
Java
import java.io.File;
public class ListFiles {
public static void main(final String... args) {
printFiles(new File("."));
}
private static void printFiles(final File file) {
System.out.println(file);
final File[] files = file.listFiles();
for (final File f : files) {
if (f.isDirectory()) {
printFiles(f);
} else {
System.out.println(f);
}
}
}
}

5. Fibonnacci
atual = 1
proximo = 1
10.times {
print atual + ' '
novo = proximo
proximo = atual + proximo
atual = novo
}

6. Importação Automática
Groovy importar automaticamente os
pacotes groovy.lang.*, groovy.util.*,
java.lang.*, java.util.*, java.net.*, and
java.io.*

7. Executando
• groovysh: Inicia o command-line shell, que é utilizado para
executar código Groovy interativamente. O código é
executado em tempo real, comando-a-comando."
• groovyConsole: Inicia a interface gráfica que também é
usada para executar código groovy interativamente; além
disso, o groovyConsole é carregado e executa os scripts
Groovy.
• groovy: Inicia o interpretador que executa scripts Groovy.

8. O compilador groovyc
groovyc –d classes Fibonacci.groovy
Fibonacci.class
Fibonacci$_run_closure1.class
java -cp $GROOVY_HOME/embeddable/groovy-all-1.0.jar:classes Fibonacci

9. Groovy e Java

10. Eclipse Plugin

11. Breve!
Java
java.net.URLEncoder.encode("a b");
Groovy
URLEncoder.encode 'a b'

12. Groovy Beans
• Métodos públicos por padrão
• Métodos de acesso por padrão
• Acesso simplificado a atributos de Beans

13. Groovy Beans
class Car {
String name
}
def car = new Car();
car.setName(‘Civic’);
car.getNome(); //Civic

14. Outer Field Access
class Bean {
public Integer value
def getValue() {
value + 1
}
}
def bean = new Bean();
bean.getValue(); //Inner Field Access
car.@value; //Outer Field Access

15. GStrings
def nick = 'Gina'
def book = 'Groovy in Action'
assert "$nick is $book" == 'Gina is Groovy in Action'

16. Regular Expressions

17. Tudo é Objeto

18. Números
def x = 1
def y = 2
assert x + y == 3
assert x.plus(y) == 3
assert x instanceof Integer

19. Listas
def nomes = [‘André’,‘Faria’]
assert nomes[1] == ‘Faria’
nomes[2] = ‘Gomes’

20. Mapas
def http = [
100 : 'CONTINUE',
200 : 'OK',
400 : 'BAD REQUEST' ]
assert http[200] == 'OK'

21. Intervalos (Ranges)
def x = 1..10
assert x.contains(5)
assert x.contains(15) == false
assert x.size() == 10
assert x.from == 1
assert x.to == 10
assert x.reverse() == 10..1

22. Closures

23. Null é False
if (null) {
assert false;
} else {
assert true;
}

24. For in
for (index in 1..10) {
}

25. For in
def list = [0,1,2,3,4,5]
for (item in list) {
}

26. Each
def list = [0,1,2,3,4,5]
list.each() { item ->
}

27. Size
Com Groovy sempre que é preciso saber
o tamanho de um objeto utiliza-se o
método size().
O Java varia entre length, size(),
getLength(), e groupCount().

28. Operadores
x+y Plus x.plus(y) Number, String, Collection
x-y Minus x.minus(y) Number, String, Collection
Number, String,
x++ Next x.next(y)
Range

29. Sobrecarga de
Operadores
class Dinheiro {
def valor
Dinheiro (valor) { this.valor = valor }
Dinheiro plus (Dinheiro other) {
new Dinheiro(this.valor + other.valor)
}
}
Dinheiro a = new Dinheiro(1)
Dinheiro b = new Dinheiro(10)
Dinheiro c = a + b

30. GStrings
me = 'Tarzan'
you = 'Jane'
line = "me $me - you $you"
assert line == 'me Tarzan - you Jane'
assert line instanceof GString
assert line.strings[0] == 'me '
assert line.strings[1] == ' - you '
assert line.values[0] == 'Tarzan'
assert line.values[1] == 'Jane'

31. Regex
def pattern = ~/foo/
assert pattern instanceof Pattern
assert pattern.matcher("foo").matches()
assert pattern.matcher("foobar").matches() == false
def cheese = ("cheesecheese" =~ /cheese/).replaceFirst("nice")
assert cheese == "nicecheese"
assert "color" == "colour".replaceFirst(/ou/, "o")

32. Numbers
10.times { /* code */ }
1.upto(5) { number -> /* code */ }
2.downto(-2) { number -> /* code */ }
valor = ''
0.step(0.5, 0.1) { number ->
valor += number + ' '
}
assert valor == '0 0.1 0.2 0.3 0.4 '

33. Ranges
range = 5..8
assert range.size() == 4
assert range.get(2) == 7
assert range[2] == 7
assert range instanceof java.util.List
assert range.contains(5)
assert range.contains(8)
range = 5..<8
assert range.size() == 3
assert range.get(2) == 7
assert range[2] == 7
assert range instanceof java.util.List
assert range.contains(5)
assert ! range.contains(8)
range = 1..10
assert range.from == 1
assert range.to == 10

34. Ordenação
def listOfCustumers = // ...
listOfCustumers.sort { custumer ->
custumer.dateOfTheFirstPurchase
}

35. Querying

36. Mapas
def myMap = [a:1, b:2, c:3]
assert myMap instanceof HashMap
assert myMap.size() == 3
assert myMap['a'] == 1
def emptyMap = [:]
assert emptyMap.size() == 0
def explicitMap = new TreeMap()
explicitMap.putAll(myMap)
assert explicitMap['a'] == 1

37. Any e Every do GDK
def map = [a:1,b:2,c:3]
assert map.every { entry -> entry.value < 10 }
assert map.any { entry -> entry.value < 2 }

38. FindAll
def map = [a:1,b:2,c:3]
def map2 = map.findAll { entry -> entry.value < 3}
assert map2.size() == 2

39. Find
def map = [a:1,b:2,c:3]
def x = map.find { entry -> entry.value == 2}

40. Closures
Closure envelope = { person ->
new Letter(person).send()
}
addressBook.each (envelope)
addressBook.each { new Letter(it).send() }

41. Closures it
new File('myfile.txt').eachLine { println it }

42. Import as
import thirdparty.MathLib as TwiceHalfMathLib
import thirdparty2.MathLib as IncMathLib
def math1 = new TwiceHalfMathLib()
def math2 = new IncMathLib()
assert 3 == math1.half(math2.increment(5))

43. Meta Programming

44. GroovyObject
public interface GroovyObject {
public Object invokeMethod(String name, Object args);
public Object getProperty(String property);
public void setProperty(String property, Object newValue);
public MetaClass getMetaClass();
public void setMetaClass(MetaClass metaClass);
}
Also Interception and Proxies

45. Builders

46. XML Builder
def builder = new groovy.xml.MarkupBuilder();
builder.numeros {
descricao 'Numeros pares'
for (i in 1..10) {
if (i % 2 == 0) {
numero (valor: i, dobro: i*2 )
}
}
}
<numeros>
<descricao>Numeros pares</descricao>
<numero valor='2' dobro='4' />
<numero valor='4' dobro='8' />
<numero valor='6' dobro='12' />
<numero valor='8' dobro='16' />
<numero valor='10' dobro='20' />
</numeros>

47. Node Builder
def builder = new NodeBuilder();
def funcionarios = builder.funcionarios {
funcionario(nome:'André Faria') {
carro(marca:'Toyota', modelo:'Corolla')
}
funcionario(nome:'Bruno Lui') {
carro(marca:'Fiat', modelo:'Palio')
}
}
def donoDoPalio = funcionarios.grep {
it.carro.any { it.'@modelo' == 'Palio' }
}.'@nome'
print donoDoPalio //Bruno Lui

48. Ant Builder
TARGET_DIR = 'documentos'
FOTOS_DIR = 'fotos'
ant = new AntBuilder()
ant.delete(dir:TARGET_DIR)
ant.copy(todir:TARGET_DIR){
fileset(dir:FOTOS_DIR, includes:'*.doc', excludes:'~*')
}

49. Swing Builder
import groovy.swing.SwingBuilder
data = [
[nick:'MrG', full:'Guillaume Laforge' ],
[nick:'jez', full:'Jeremy Rayner' ],
[nick:'fraz', full:'Franck Rasolo' ],
[nick:'sormuras', full:'Christian Stein' ],
[nick:'blackdrag', full:'Jochen Theodorou' ],
[nick:'Mittie', full:'Dierk Koenig' ]
]
swing = new SwingBuilder()
frame = swing.frame(title:'Table Demo') {
scrollPane {
table() {
tableModel(list:data) {
propertyColumn(header:'Nickname', propertyName:'nick')
propertyColumn(header:'Full Name',propertyName:'full')
}
}
}
}
frame.pack()
frame.show()

50. Templates

51. Template
def mensagem = '''
Querido amigo ${destinatario}
Gostaria de pedir que me ajudasse a realizar essas ${tarefas.size} tarefas:
<% tarefas.each() { %> - ${it}
<% } %>
'''
def engine = new groovy.text.SimpleTemplateEngine();
def template = engine.createTemplate(mensagem);
def parametros = [
destinatario: 'Zé das Couves',
tarefas: ['comprar um ovo de páscoa', 'regar as plantas']
]
print template.make(parametros).toString()
Querido amigo Zé das Couves
Gostaria de pedir que me ajudasse a realizar essas 2 tarefas:
- comprar um ovo de páscoa
- regar as plantas

52. Groovylets

53. Groovylets
<!DOCTYPE web-app
PUBLIC "-//Sun Microsystems, Inc.//DTD Web Application 2.2//EN"
"http://java.sun.com/j2ee/dtds/web-app_2_2.dtd" >
<web-app>
<display-name>Groovlet Demonstrator</display-name>
<description>
Showing the use of Groovlets for Groovy in Action
</description>
<servlet>
<servlet-name>Groovy</servlet-name>
<servlet-class>groovy.servlet.GroovyServlet</servlet-class>
</servlet>
<servlet-mapping>
<servlet-name>Groovy</servlet-name>
<url-pattern>*</url-pattern>
</servlet-mapping>
</web-app>

54. Groovylets
html.html{
head { title 'Groovlet Demonstrator' }
body {
h1 'Variables in the Binding:'
table(summary:'binding') {
tbody {
binding.variables.each { key, value ->
tr {
td key.toString()
td(value ? value.toString() : 'null')
}
}
}
}
}
}

55. Groovylets + Templates
<html>
<head>
<title>Think of a Number</title>
</head>
<body>
<h1>Think of a Number</h1>
Your guess $guess is <%
switch (guess) {
case goal : out << 'correct!'; break
case {it < goal} : out << 'too low' ; break
case {it > goal} : out << 'too high'; break
}
%>
<p>What&quot;s your guess (0..100)?</p>
<form action='Templater.groovy'>
<input type='text' name='guess'>
<button type='submit'>Guess</button>
<button type='submit' name='restart' value='true'>New Game
</button>
</form>
</body>
</html>
def engine = new groovy.text.SimpleTemplateEngine()
def source = getClass().classLoader.getResource('/Number.template.html')
def template = engine.createTemplate(source)
out << template.make(goal:50, guess:49)

56. Groovy Shell
final GroovyShell groovyShell = new GroovyShell();
final String result = (String) groovyShell.evaluate(" new File('.').eachFile { println it } ");
System.out.println(result);

57. Integração com Spring

58. Grails

59. Referência