© ASERT 2006-2009
Groovy Tutorial
Dr Paul King
paulk@asert.com.au
ASERT, Australia

What is Groovy?
• “Groovy is like a super version
of Java. It can leverage Java's
enterprise capabilities but also
has cool productivity features like closures,
DSL support, builders and dynamic typing.”
@ ASERT 2006-2009
Groovy = Java – boiler plate code
+ optional dynamic typing
+ closures
+ domain specific languages
+ builders
+ metaprogramming
JUL 2009 - 2

Groovy Goodies Overview
• Fully object oriented
• Closures: reusable
and assignable
pieces of code
• Operators can be • GPath: efficient
overloaded
@ ASERT 2006-2009
object navigation
• Multimethods • GroovyBeans
• Literal declaration for • grep and switch
lists (arrays), maps,
ranges and regular • Templates, builder,
expressions swing, Ant, markup,
XML, SQL, XML-RPC,
Scriptom, Grails,
tests, Mocks JUL 2009 - 3

Growing Acceptance …
A slow and steady start but now gaining in
momentum, maturity and mindshare
Making
Java
Groovy
(soon)
Now free

… Growing Acceptance …
© ASERT 2006-2009
JUL 2009 - 5

… Growing Acceptance …
© ASERT 2006-2009
Groovy and
Grails downloads:
70-90K per month
and growing
JUL 2009 - 6

… Growing Acceptance …
© ASERT 2006-2009
Source: http://www.micropoll.com/akira/mpresult/501697-116746
Source: http://www.grailspodcast.com/
JUL 2009 - 7

… Growing Acceptance …
© ASERT 2006-2009
http://www.jroller.com/scolebourne/entry/devoxx_2008_whiteboard_votes
http://www.java.net
JUL 2009 - 8

… Growing Acceptance
© ASERT 2006-2009
JUL 2009 - 9

The Landscape of JVM Languages
optional
static
types
@ ASERT 2006-2009
Dynamic features call
for dynamic types Java bytecode calls
for static types
The terms “Java Virtual Machine” and “JVM” mean a Virtual Machine for the Java™ platform.
JUL 2009 - 10

Groovy Starter
System.out.println("Hello, World!"); // optional semicolon,
println 'Hello, World!' // System.out, brackets,
// main() method, class defn
def name = 'Guillaume' // dynamic typing
println "$name, I'll get the car." // GString
String longer = """${name}, the car
is in the next row.""" // multi-line string
@ ASERT 2006-2009
// with static typing
assert 0.5 == 1/2 // BigDecimal equals()
def printSize(obj) { // optional duck typing
print obj?.size() // safe dereferencing
}
def pets = ['ant', 'bee', 'cat'] // native list syntax
pets.each { pet -> // closure support
assert pet < 'dog' // overloading '<' on String
} // or: for (pet in pets)...
JUL 2009 - 11

A Better Java...
import java.util.List;
import java.util.ArrayList;
class Erase {
private List removeLongerThan(List strings, int length) { This code
List result = new ArrayList();
for (int i = 0; i < strings.size(); i++) {
is valid
String s = (String) strings.get(i); Java and
if (s.length() <= length) {
result.add(s); valid Groovy
}
}
@ ASERT 2006-2009
return result;
}
public static void main(String[] args) {
List names = new ArrayList();
names.add("Ted"); names.add("Fred");
names.add("Jed"); names.add("Ned");
System.out.println(names);
Based on an
Erase e = new Erase(); example by
List shortNames = e.removeLongerThan(names, 3); Jim Weirich
System.out.println(shortNames.size());
for (int i = 0; i < shortNames.size(); i++) { & Ted Leung
String s = (String) shortNames.get(i);
System.out.println(s);
}
}
}
JUL 2009 - 12

...A Better Java...
import java.util.List;
import java.util.ArrayList;
class Erase {
private List removeLongerThan(List strings, int length) { Do the
List result = new ArrayList();
for (int i = 0; i < strings.size(); i++) {
semicolons
String s = (String) strings.get(i); add anything?
if (s.length() <= length) {
result.add(s); And shouldn‟t
}
} we us more
@ ASERT 2006-2009
}
return result; modern list
public static void main(String[] args) { notation?
List names = new ArrayList();
names.add("Ted"); names.add("Fred"); Why not
names.add("Jed"); names.add("Ned");
System.out.println(names);
import common
Erase e = new Erase(); libraries?
List shortNames = e.removeLongerThan(names, 3);
System.out.println(shortNames.size());
for (int i = 0; i < shortNames.size(); i++) {
String s = (String) shortNames.get(i);
System.out.println(s);
}
}
}
JUL 2009 - 13

...A Better Java...
class Erase {
private List removeLongerThan(List strings, int length) {
List result = new ArrayList()
for (String s in strings) {
if (s.length() <= length) {
result.add(s)
}
}
return result
}
public static void main(String[] args) {
@ ASERT 2006-2009
List names = new ArrayList()
names.add("Ted"); names.add("Fred")
names.add("Jed"); names.add("Ned")
System.out.println(names)
Erase e = new Erase()
List shortNames = e.removeLongerThan(names, 3)
System.out.println(shortNames.size())
for (String s in shortNames) {
System.out.println(s)
}
}
}
JUL 2009 - 14

...A Better Java...
class Erase {
private List removeLongerThan(List strings, int length) {
List result = new ArrayList()
for (String s in strings) {
if (s.length() <= length) {
result.add(s)
Do we need
} the static types?
}
return result Must we always
}
have a main
public static void main(String[] args) { method and
@ ASERT 2006-2009
List names = new ArrayList()
names.add("Ted"); names.add("Fred") class definition?
names.add("Jed"); names.add("Ned")
System.out.println(names) How about
Erase e = new Erase()
List shortNames = e.removeLongerThan(names, 3)
improved
System.out.println(shortNames.size()) consistency?
for (String s in shortNames) {
System.out.println(s)
}
}
}
JUL 2009 - 15

...A Better Java...
def removeLongerThan(strings, length) {
def result = new ArrayList()
for (s in strings) {
if (s.size() <= length) {
result.add(s)
}
}
return result
}
@ ASERT 2006-2009
names = new ArrayList()
names.add("Ted")
names.add("Fred")
names.add("Jed")
names.add("Ned")
System.out.println(names)
shortNames = removeLongerThan(names, 3)
System.out.println(shortNames.size())
for (s in shortNames) {
System.out.println(s)
}
JUL 2009 - 16

...A Better Java...
def removeLongerThan(strings, length) {
def result = new ArrayList()
for (s in strings) {
if (s.size() <= length) {
result.add(s) Shouldn‟t we
}
} have special
return result notation for lists?
}
And special
@ ASERT 2006-2009
names = new ArrayList() facilities for
names.add("Ted")
names.add("Fred") list processing?
names.add("Jed") Is „return‟
names.add("Ned")
System.out.println(names) needed at end?
shortNames = removeLongerThan(names, 3)
System.out.println(shortNames.size())
for (s in shortNames) {
System.out.println(s)
}
JUL 2009 - 17

...A Better Java...
def removeLongerThan(strings, length) {
strings.findAll{ it.size() <= length }
}
names = ["Ted", "Fred", "Jed", "Ned"]
System.out.println(names)
shortNames = removeLongerThan(names, 3)
System.out.println(shortNames.size())
shortNames.each{ System.out.println(s) }
@ ASERT 2006-2009
JUL 2009 - 18

...A Better Java...
def removeLongerThan(strings, length) {
strings.findAll{ it.size() <= length }
}
Is the method
names = ["Ted", "Fred", "Jed", "Ned"] now needed?
System.out.println(names)
shortNames = removeLongerThan(names, 3) Easier ways to
System.out.println(shortNames.size()) use common
shortNames.each{ System.out.println(s) }
methods?
@ ASERT 2006-2009
Are brackets
required here?
JUL 2009 - 19

...A Better Java...
names = ["Ted", "Fred", "Jed", "Ned"]
println names
shortNames = names.findAll{ it.size() <= 3 }
println shortNames.size()
shortNames.each{ println it }
@ ASERT 2006-2009
JUL 2009 - 20

...A Better Java
names = ["Ted", "Fred", "Jed", "Ned"]
println names
shortNames = names.findAll{ it.size() <= 3 }
println shortNames.size()
shortNames.each{ println it }
@ ASERT 2006-2009
["Ted", "Fred", "Jed", "Ned"]
3
Ted
Jed
Ned
JUL 2009 - 21

Better JavaBeans...
import java.math.BigDecimal; ...
public class BikeJavaBean { public void setModel(String model) {
private String manufacturer; this.model = model;
private String model; }
private int frame;
private String serialNo; public int getFrame() {
private double weight; return frame;
private String status; }
private BigDecimal cost;
public String getSerialNo() {
public BikeJavaBean(String manufacturer, String model, return serialNo;
int frame, String serialNo, }
double weight, String status) {
this.manufacturer = manufacturer; public void setSerialNo(String serialNo) {
this.model = model; this.serialNo = serialNo;
this.frame = frame; }
this.serialNo = serialNo;
@ ASERT 2006-2009
this.weight = weight; public double getWeight() {
this.status = status; return weight;
} }
public String toString() { public void setWeight(double weight) {
return "Bike:“ + this.weight = weight;
“n manufacturer -- " + manufacturer + }
"n model -- " + model +
"n frame -- " + frame + public String getStatus() {
"n serialNo -- " + serialNo + return status;
"n"; }
}
public void setStatus(String status) {
public String getManufacturer() { this.status = status;
return manufacturer; }
}
public BigDecimal getCost() {
public void setManufacturer(String manufacturer) { return cost;
this.manufacturer = manufacturer; }
}
public void setCost(BigDecimal cost) {
public String getModel() { this.cost = cost.setScale(3, BigDecimal.ROUND_HALF_UP);
return model; }
} }
...
Modified example from: http://www.ibm.com/developerworks/library/j-pg09196.html JUL 2009 - 22

...Better JavaBeans...
import java.math.BigDecimal; ...
public class BikeJavaBean { public void setModel(String model) {
Auto
private String manufacturer; this.model = model;
private String model;
private int frame;
} getters?
private String serialNo;
private double weight;
private String status;
public int getFrame() {
}
return frame; Auto
private BigDecimal cost;
public String getSerialNo() {
setters?
public BikeJavaBean(String manufacturer, String model, return serialNo;
int frame, String serialNo,
double weight, String status) {
} Auto
this.manufacturer = manufacturer;
this.model = model;
this.frame = frame; }
this.serialNo = serialNo; construction?
public void setSerialNo(String serialNo) {
this.serialNo = serialNo;
@ ASERT 2006-2009
this.weight = weight; public double getWeight() {
this.status = status; return weight;
} }
public String toString() { public void setWeight(double weight) {
return "Bike:“ + this.weight = weight;
“n manufacturer -- " + manufacturer + }
"n model -- " + model +
"n frame -- " + frame + public String getStatus() {
"n serialNo -- " + serialNo + return status;
"n"; }
}
public void setStatus(String status) {
public String getManufacturer() { this.status = status;
return manufacturer; }
}
public BigDecimal getCost() {
public void setManufacturer(String manufacturer) { return cost;
this.manufacturer = manufacturer; }
}
public void setCost(BigDecimal cost) {
public String getModel() { this.cost = cost.setScale(3, BigDecimal.ROUND_HALF_UP);
return model; }
} }
...
JUL 2009 - 23

... Better JavaBeans ...
class BikeGroovyBean {
String manufacturer, model, serialNo, status
final Integer frame
Double weight
BigDecimal cost
public void setCost(BigDecimal newCost) {
cost = newCost.setScale(3, BigDecimal.ROUND_HALF_UP)
@ ASERT 2006-2009
}
public String toString() {
return """Bike:
manufacturer -- $manufacturer
model -- $model More complicated than
frame -- $frame normal because we want:
serialNo -- $serialNo * Read only frame
""" * Custom setter for cost
} * Custom toString()
}
JUL 2009 - 24

... Better JavaBeans
class BikeGroovyBean {
String manufacturer, model, serialNo, status
Integer frame
Double weight
BigDecimal cost
}
@ ASERT 2006-2009
In more typical
cases it is often
as simple as this.
JUL 2009 - 25

Better Strings
• Several forms
– Single quotes for // normal strings
simple strings def firstname = 'Kate'
def surname= "Bush"
– Double quotes for assert firstname * 2 == 'KateKate'
GStrings which
// GString
support variable def fullname = "$firstname $surname"
@ ASERT 2006-2009
expansion assert fullname == 'Kate Bush'
– Slashy strings assert fullname - firstname == ' Bush'
assert fullname.padLeft(10) ==
behave like ' Kate Bush'
GStrings but
preserve // indexing (including ranges)
assert fullname[0..3] == firstname
backslashes (great assert fullname[-4..-1] == surname
for regex and assert fullname[5, 3..1] == 'Beta'
directory names)
– Multi-line versions
JUL 2009 - 26

…Better Strings…
// slashy string: (almost) no escaping
// Multi-line strings def path = /C:WindowsSystem32/
def twister = '''
She sells, sea shells def plain = 'nrtbf$'
By the sea shore''' assert plain.size() == 7
def slashy = /nrtbf$/
def lines = assert slashy.size() == 14
twister.split('n')
assert lines.size() == 2 // late binding trick with closures
@ ASERT 2006-2009
fullname = "${-> firstname} $surname"
def address = """ assert fullname == 'Kate Bush'
$fullname firstname = 'George'
123 First Ave surname = 'Clooney'
New York assert fullname == 'George Bush'
""".trim()
println """
def lines = ----------------------
address.split('n') | $fullname |
assert lines.size() == 3 | 123 First Ave |
| New York |
----------------------
"""
JUL 2009 - 27

…Better Strings
// more substrings
string = 'hippopotamus'
assert string - 'hippo' - 'mus' + 'to' == 'potato'
assert string.replace('ppopotam','bisc') == 'hibiscus'
// processing characters
assert 'apple'.toList() == ['a', 'p', 'p', 'l', 'e']
//also: 'apple' as String[], 'apple'.split('')
@ ASERT 2006-2009
string = "an apple a day"
assert string.toList().unique().sort().join() == '
adelnpy'
// reversing chars/words
assert 'string'.reverse() == 'gnirts'
string = 'Yoda said, "can you see this?"'
revwords = string.split(' ').toList().reverse().join(' ')
assert revwords == 'this?" see you "can said, Yoda'
JUL 2009 - 28

Better Lists, Maps, Ranges
• Lists
– Special syntax for list literals
– Additional common methods (operator overloading)
def list = [3, new Date(), 'Jan']
assert list + list == list * 2
• Maps
@ ASERT 2006-2009
– Special syntax for map literals
– Additional common methods
def map = [a: 1, b: 2]
assert map['a'] == 1 && map.b == 2
• Ranges
– Special syntax for various kinds of ranges
def letters = 'a'..'z'
def numbers = 0..<10
JUL 2009 - 29

Better Control Structures: Branching/Loops
• Branching and loops • Loop-like Closures
for (int i = 0; i < n; i++) { } myMap.each { key, value ->
for (Type item : iterable) { } println "$key : $value"
for (item in iterable) { } }
// if (condition) ... // each, every, collect, any,
// else if (condition) ... // inject, find, findAll,
// else ... // upto, downto, times, grep,
@ ASERT 2006-2009
// throw, try...catch...finally // reverseEach, eachMatch,
// for, while // eachWithIndex, eachLine
// d = a ? b : c // eachFile, eachFileMatch,
// a = b ?: c // eachByte, combinations ...
// d = a?.b?.c
• Groovy Truth words = ['bob', 'alpha',
if (1) // ... 'rotator', 'omega', 'reviver']
if (object) // ... bigPalindromes = words.findAll{ w ->
if (collection) // ... w == w.reverse() && w.size() > 5}
if (map) // ... assert bigPalindromes ==
if (matcher) // ... ['rotator', 'reviver']
JUL 2009 - 30

Better Control Structures: Switch
switch (10) {
case 0 : assert false ; break
case 0..9 : assert false ; break
case [8,9,11] : assert false ; break
case Float : assert false ; break
case {it%3 == 0} : assert false ; break
case ~/../ : assert true ; break
@ ASERT 2006-2009
default : assert false ; break
}
• Extensible
– Implement your own isCase() method
JUL 2009 - 31

Better Control Structures: Switch – Custom isCase
WARNING:
class Color { Advanced
def name
Topic!
static yellow = new Color(name:'Yellow')
static orange = new Color(name:'Orange')
def isCase(candidate) {
candidate.color == name Found something Yellow
} Found something Orange
}
Unknown color
@ ASERT 2006-2009
import static Color.*
class Banana { def color = 'Yellow' }
class Orange { def color = 'Orange' }
class Grape { def color = 'Purple' }
fruits = [new Banana(), new Orange(), new Grape()]
fruits.each { println inspectFruit(it) }
def inspectFruit(f) {
switch (f) {
case yellow: return 'Found something Yellow'
case orange: return 'Found something Orange'
default: return 'Unknown color'
}
}
JUL 2009 - 32

Better Control Structures: Switch Poker…
hand1 hand2
8C TS KC 9H 4S 7D 2S 5D 3S AC
suites = 'SHDC'
ranks = '23456789TJQKA'
suite = { String card -> suites.indexOf(card[1]) }
rank = { String card -> ranks.indexOf(card[0]) }
rankSizes = { List cards ->
@ ASERT 2006-2009
cards.groupBy(rank).collect{ k, v -> v.size() }.sort() }
rankValues = { List cards ->
cards.collect{ rank(it) }.sort() }
// ...
println rankSizes(["7S", "7H", "2H", "7D", "AH"])
// => [1, 1, 3]
JUL 2009 - 33

…Better Control Structures: Switch Poker…
// ...
flush = { List cards -> cards.groupBy(suite).size() == 1 }
straight = { def v = rankValues(it); v == v[0]..v[0]+4 }
straightFlush = { List cards -> straight(cards) && flush(cards) }
@ ASERT 2006-2009
fourOfAKind = { List cards -> rankSizes(cards) == [1, 4] }
fullHouse = { List cards -> rankSizes(cards) == [2, 3] }
threeOfAKind = { List cards -> rankSizes(cards) == [1, 1, 3] }
twoPair = { List cards -> rankSizes(cards) == [1, 2, 2] }
pair = { List cards -> rankSizes(cards) == [1, 1, 1, 2] }
// ...
JUL 2009 - 34

… Better Control Structures: Switch Poker
// ...
def rankHand(List cards) {
switch (cards) {
case straightFlush : return 9
case fourOfAKind : return 8
case fullHouse : return 7
case flush : return 6
@ ASERT 2006-2009
case straight : return 5
case threeOfAKind : return 4
case twoPair : return 3
case pair : return 2
default : return 1
}
}
// ...
JUL 2009 - 35

Using Closures...
• Traditional mainstream languages
– Data can be stored in variables, passed around,
combined in structured ways to form more complex
data; code stays put where it is defined
• Languages supporting closures
– Data and code can be stored in variables, passed
@ ASERT 2006-2009
around, combined in structured ways to form more
complex algorithms and data
doubleNum = { num -> num * 2 }
println doubleNum(3) // => 6
processThenPrint = { num, closure ->
num = closure(num); println "num is $num"
}
processThenPrint(3, doubleNum) // => num is 6
processThenPrint(10) { it / 2 } // => num is 5
JUL 2009 - 36

...Using Closures...
import static Math.* Algorithm piE differs by 1.0206946399193839E-11
Algorithm piF differs by 1.0070735356748628E-9
Algorithm piC differs by 2.668102068170697E-7
piA = { 22 / 7 } Algorithm piD differs by 4.813291008076703E-5
piB = { 333/106 } Algorithm piB differs by 8.321958979307098E-5
piC = { 355/113 } Algorithm piA differs by 0.001264489310206951
piD = { 0.6 * (3 + sqrt(5)) }
piE = { 22/17 + 37/47 + 88/83 }
piF = { sqrt(sqrt(2143/22)) }
@ ASERT 2006-2009
howCloseToPI = { abs(it.value() - PI) }
algorithms = [piA:piA, piB:piB, piC:piC,
piD:piD, piE:piE, piF:piF]
findBestPI(algorithms)
def findBestPI(map) {
map.entrySet().sort(howCloseToPI).each { entry ->
def diff = howCloseToPI(entry)
println "Algorithm $entry.key differs by $diff"
}
}
JUL 2009 - 37

...Using Closures...
• Used for many things in Groovy:
• Iterators new File('/x.txt').eachLine {
println it
• Callbacks }
• Higher-order functions
• Specialized control structures
• Dynamic method definition
@ ASERT 2006-2009
• Resource allocation 3.times { println 'Hi' }
• Threads
[0, 1, 2].each { number ->
• Continuations println number
}
def houston(Closure doit) {
(10..1).each { count -> [0, 1, 2].each { println it}
doit(count)
} def printit = { println it }
} [0, 1, 2].each printit
houston { println it }
JUL 2009 - 38

...Using Closures...
map = ['a': 1, 'b': 2]
map.each {key, value -> map[key] = value * 2}
assert map == ['a': 2, 'b': 4]
doubler = {key, value -> map[key] = value * 2}
map.each(doubler)
@ ASERT 2006-2009
assert map == ['a': 4, 'b': 8]
def doubleMethod(entry) {
map[entry.key] = entry.value * 2
}
doubler = this.&doubleMethod
map.each(doubler)
assert map == ['a': 8, 'b': 16]
JUL 2009 - 39

...Using Closures...
assert [1, 2, 3].grep{ it < 3 } == [1, 2]
assert [1, 2, 3].any{ it % 2 == 0 }
assert [1, 2, 3].every{ it < 4 }
assert (1..9).collect{it}.join() == '123456789'
assert (1..4).collect{it * 2}.join() == '2468'
def add = { x, y -> x + y }
@ ASERT 2006-2009
def mult = { x, y -> x * y }
assert add(1, 3) == 4
assert mult(1, 3) == 3
def min = { x, y -> [x, y].min() }
def max = { x, y -> [x, y].max() }
def triple = mult.curry(3); assert triple(2) == 6
def atLeastTen = max.curry(10)
assert atLeastTen(5) == 10
assert atLeastTen(15) == 15
JUL 2009 - 40

...Using Closures
def pairWise(list, Closure invoke) {
if (list.size() < 2) return []
def next = invoke(list[0], list[1])
return [next] + pairWise(list[1..-1], invoke)
}
@ ASERT 2006-2009
// using min, max, etc. From previous slide
assert pairWise(1..5, add) == [3, 5, 7, 9]
assert pairWise(1..5, mult) == [2, 6, 12, 20]
assert pairWise(1..5, min) == [1, 2, 3, 4]
assert pairWise(1..5, max) == [2, 3, 4, 5]
assert 'cbaxabc' == ['a', 'b', 'c'].inject('x') {
result, item -> item + result + item
}
JUL 2009 - 41

Better Regular Expressions
assert "Hello World!" =~ /Hello/ // Find operator
assert "Hello World!" ==~ /Hellob.*/ // Match operator
def p = ~/Hellob.*/ // Pattern operator
assert p.class.name == 'java.util.regex.Pattern'
def input = "Voting is open between 01 Nov 2008 and 04 Nov 2008"
@ ASERT 2006-2009
def matches = (input =~ /dd? ... d{4}/)
matches.each { m -> 01 Nov 2008
println m 04 Nov 2008
}
def matchingGroups = (input =~ /(dd?) (...) (d{4})/)
matchingGroups.each { all, d, m, y ->
println "$d/$m/$y" 01/Nov/2008
} 04/Nov/2008
JUL 2009 - 42

Better Dates...
• Similar to Java
– Use java.util.Date, java.util.Calendar, java.sql.Date, ...
– Can use static imports to help
– Or 3rd party package like Joda Time
• Special support for changing times:
@ ASERT 2006-2009
date2 = date1 + 1 // day
date2 = date1 + 1.week – 3.days + 6.hours
• Utility methods for date input and output
– Date.parse(formatString, dateString)
– date.format(formatString)
– date.timeString, date.dateString, date.dateTimeString
• Potentially will change with JSR 310
JUL 2009 - 43

...Better Dates...
import static java.util.Calendar.getInstance as now
import java.util.GregorianCalendar as D
import org.codehaus.groovy.runtime.TimeCategory
println new D(2007,11,25).time
println now().time Tue Dec 25 00:00:00 EST 2007
Thu Jun 28 10:10:34 EST 2007
def date = new Date() + 1 Fri Jun 29 10:10:35 EST 2007
@ ASERT 2006-2009
println date Tue Jul 17 11:10:35 EST 2007
Date was Jun/03/1998
use(TimeCategory) {
println new Date() + 1.hour + 3.weeks - 2.days
}
dateStr = "1998-06-03"
date = Date.parse("yyyy-MM-dd", dateStr)
println 'Date was ' + date.format("MMM/dd/yyyy")
def holidays = boxingDay..newYearsEve
JUL 2009 - 44

...Better Dates
import static java.util.Calendar.*
def nowCal = Calendar.instance
y = nowCal.get(YEAR)
Date nowDate = nowCal.time
def (m, d) = [nowDate[MONTH] + 1, nowDate[DATE]]
println "Today is $d $m $y"
nowCal.set DATE, 1
nowCal.set MONTH, FEBRUARY
println "Changed to $nowCal.time"
@ ASERT 2006-2009
Today is 26 9 2008
Changed to Fri Feb 01 23:05:20 EST 2008
cal = Calendar.instance
cal.set 1988, APRIL, 4, 0, 0, 0
date = cal.time
def (doy, woy, y) = [DAY_OF_YEAR, WEEK_OF_YEAR,
YEAR].collect{ date[it] }
println "$date is day $doy and week $woy of year $y"
Mon Apr 04 00:00:00 EST 1988 is day 95 and week 15 of year 1988
JUL 2009 - 45

Better Design Patterns: Builder
• Markup Builder
<html>
import groovy.xml.*
<head>
def page = new MarkupBuilder()
<title>Hello</title>
page.html {
</head>
head { title 'Hello' }
<body>
@ ASERT 2006-2009
body {
<ul>
ul {
<li>world 1</li>
for (count in 1..5) {
<li>world 2</li>
li "world $count"
<li>world 3</li>
} } } }
<li>world 4</li>
<li>world 5</li>
</ul>
</body>
</html>
JUL 2009 - 46

SwingBuilder
import java.awt.FlowLayout
builder = new groovy.swing.SwingBuilder()
langs = ["Groovy", "Ruby", "Python", "Pnuts"]
gui = builder.frame(size: [290, 100],
title: 'Swinging with Groovy!') {
panel(layout: new FlowLayout()) {
panel(layout: new FlowLayout()) {
for (lang in langs) {
@ ASERT 2006-2009
checkBox(text: lang)
}
}
button(text: 'Groovy Button', actionPerformed: {
builder.optionPane(message: 'Indubitably Groovy!').
createDialog(null, 'Zen Message').show()
})
button(text: 'Groovy Quit',
actionPerformed: {System.exit(0)})
}
}
gui.show()
Source: http://www.ibm.com/developerworks/java/library/j-pg04125/
JUL 2009 - 47

SwingXBuilder
import groovy.swing.SwingXBuilder
@ ASERT 2006-2009
import static java.awt.Color.*
import static java.lang.Math.*
def swing = new SwingXBuilder()
def frame = swing.frame(size: [300, 300]) {
graph(plots: [
[GREEN, {value -> sin(value)}],
[BLUE, {value -> cos(value)}],
[RED, {value -> tan(value)}]
])
}.show()
JUL 2009 - 48

GraphicsBuilder
def colors = ['red','darkOrange','blue','darkGreen']
(0..3).each { index ->
star( cx: 50 + (index*110), cy: 50, or: 40, ir: 15,
borderColor: 'black', count: 2+index, fill: colors[index] )
star( cx: 50 + (index*110), cy: 140, or: 40, ir: 15,
borderColor: 'black‘, count: 7+index, fill: colors[index] )
}
@ ASERT 2006-2009
JUL 2009 - 49

AntBuilder...
def ant = new AntBuilder()
ant.echo("hello") // let's just call one task
// create a block of Ant using the builder pattern
ant.sequential {
myDir = "target/AntTest/"
mkdir(dir: myDir)
@ ASERT 2006-2009
copy(todir: myDir) {
fileset(dir: "src/test") {
include(name: "**/*.groovy")
}
}
echo("done")
}
// now let's do some normal Groovy again
file = new File("target/test/AntTest.groovy")
assert file.exists()
JUL 2009 - 50

...AntBuilder
def ant = new AntBuilder()
ant.echo(file:'Temp.java', '''
class Temp {
public static void main(String[] args) {
System.out.println("Hello");
}
}
@ ASERT 2006-2009
''')
ant.with {
javac(srcdir:'.', includes:'Temp.java', fork:'true')
java(classpath:'.', classname:'Temp', fork:'true')
echo('Done')
}
// =>
// [javac] Compiling 1 source file
// [java] Hello
// [echo] Done
JUL 2009 - 51

Using AntLibs: Maven Ant Tasks & AntUnit
import static groovy.xml.NamespaceBuilder.newInstance as namespace
def ant = new AntBuilder()
def mvn = namespace(ant, 'antlib:org.apache.maven.artifact.ant')
def antunit = namespace(ant, 'antlib:org.apache.ant.antunit')
direct = [groupId:'jfree', artifactId:'jfreechart', version:'1.0.9']
indirect = [groupId:'jfree', artifactId:'jcommon', version:'1.0.12']
// download artifacts
@ ASERT 2006-2009
mvn.dependencies(filesetId:'artifacts') { dependency(direct) }
// print out what we downloaded
ant.fileScanner { fileset(refid:'artifacts') }.each { println it }
// use AntUnit to confirm expected files were downloaded
def prefix = System.properties.'user.home' + '/.m2/repository'
[direct, indirect].each { item ->
def (g, a, v) = [item.groupId, item.artifactId, item.version]
antunit.assertFileExists(file:"$prefix/$g/$a/$v/$a-${v}.jar")
}
C:Userspaulk.m2repositoryjfreejcommon1.0.12jcommon-1.0.12.jar
C:Userspaulk.m2repositoryjfreejfreechart1.0.9jfreechart-1.0.9.jar
JUL 2009 - 52

Better File Manipulation...
import java.util.List;
import java.util.ArrayList;
import java.util.Arrays;
import java.io.File; // ...
import java.io.FileOutputStream; private static void processFile(File file, PrintWriter out) {
import java.io.PrintWriter; FileInputStream fis = null;
import java.io.FileNotFoundException; InputStreamReader isr = null;
import java.io.IOException; BufferedReader reader = null;
import java.io.BufferedReader; try {
import java.io.InputStreamReader; fis = new FileInputStream(file);
import java.io.FileInputStream; isr = new InputStreamReader(fis);
reader = new BufferedReader(isr);
public class PrintJavaSourceFileLinesThatContainTheWordJava { String nextline;
public static void main(String[] args) { int count = 0;
File outfile = new File("result.txt"); while ((nextline = reader.readLine()) != null) {
outfile.delete(); count++;
File basedir = new File(".."); if (nextline.toLowerCase().contains("java")) {
List<File> files = new ArrayList<File>(); out.println("File '" + file +
files.add(basedir); "' on line " + count);
© ASERT 2006-2009
FileOutputStream fos = null; out.println(nextline);
PrintWriter out = null; out.println();
try { }
fos = new FileOutputStream(outfile); }
out = new PrintWriter(fos); } catch (FileNotFoundException e) {
while (!files.isEmpty()) { e.printStackTrace();
File file = files.remove(0); } catch (IOException e) {
if (file.isDirectory()) { e.printStackTrace();
files.addAll(Arrays.asList(file.listFiles())); } finally {
} else { if (reader != null) {
if (file.getName().endsWith(".java")) { try { reader.close(); }
processFile(file, out); catch (IOException e) { e.printStackTrace(); }
} }
} if (isr != null) {
} try { isr.close(); }
} catch (FileNotFoundException e) { catch (IOException e) { e.printStackTrace(); }
e.printStackTrace(); }
} finally { if (fis != null) {
if (out != null) { out.close(); } try { fis.close(); }
if (fos != null) { catch (IOException e) { e.printStackTrace(); }
try { fos.close(); } }
catch (IOException e) { e.printStackTrace(); } }
} }
} }
}
// ...
JUL 2009 - 53

...Better File Manipulation...
import java.util.List;
import
import
java.util.ArrayList;
java.util.Arrays;
boilerplate
import java.io.File; // ...
import java.io.FileOutputStream; private static void processFile(File file, PrintWriter out) {
import java.io.PrintWriter; FileInputStream fis = null;
import java.io.FileNotFoundException; InputStreamReader isr = null;
import java.io.IOException; BufferedReader reader = null;
import java.io.BufferedReader; try {
import java.io.InputStreamReader; fis = new FileInputStream(file);
import java.io.FileInputStream; isr = new InputStreamReader(fis);
reader = new BufferedReader(isr);
public class PrintJavaSourceFileLinesThatContainTheWordJava { String nextline;
public static void main(String[] args) { int count = 0;
File outfile = new File("result.txt"); while ((nextline = reader.readLine()) != null) {
outfile.delete(); count++;
File basedir = new File(".."); if (nextline.toLowerCase().contains("java")) {
List<File> files = new ArrayList<File>(); out.println("File '" + file +
files.add(basedir); "' on line " + count);
© ASERT 2006-2009
FileOutputStream fos = null; out.println(nextline);
PrintWriter out = null; out.println();
try { }
fos = new FileOutputStream(outfile); }
out = new PrintWriter(fos); } catch (FileNotFoundException e) {
while (!files.isEmpty()) { e.printStackTrace();
File file = files.remove(0); } catch (IOException e) {
if (file.isDirectory()) { e.printStackTrace();
files.addAll(Arrays.asList(file.listFiles())); } finally {
} else { if (reader != null) {
if (file.getName().endsWith(".java")) { try { reader.close(); }
processFile(file, out); catch (IOException e) { e.printStackTrace(); }
} }
} if (isr != null) {
} try { isr.close(); }
} catch (FileNotFoundException e) { catch (IOException e) { e.printStackTrace(); }
e.printStackTrace(); }
} finally { if (fis != null) {
if (out != null) { out.close(); } try { fis.close(); }
if (fos != null) { catch (IOException e) { e.printStackTrace(); }
try { fos.close(); } }
catch (IOException e) { e.printStackTrace(); } }
} }
} }
}
// ...
JUL 2009 - 54

...Better File Manipulation
def out = new File('result.txt')
out.delete()
new File('..').eachFileRecurse {file ->
if (file.name.endsWith('.groovy')) {
file.eachLine { line, num ->
if (line.toLowerCase().contains('groovy'))
out <<
© ASERT 2006-2009
"File '$file' on line $numn$linenn"
}
}
} File '..filessrcPrintGroovySourceLines.groovy' on line 4
if (file.name.endsWith('.groovy')) {
File '..filessrcPrintGroovySourceLines.groovy' on line 6
if (line.toLowerCase().contains('groovy'))
File '..jdbcsrcJdbcGroovy.groovy' on line 1
import groovy.sql.Sql
…
JUL 2009 - 55

Better Process Management...
// windows version (minimal error/output)
def p = "cmd /c dir *.xml".execute()
p.waitFor()
if (p.exitValue()) println p.err.text
else println p.text
----- stdout -----
Volume in drive D is DATA
Volume Serial Number is FC5C-B39D
© ASERT 2006-2009
Directory of D:svntrunk-groovygroovy-core
// unix version
27/06/2009 10:13 AM 38,478 build.xml
def p = "ls *.xml".execute() 29/06/2009 06:53 PM 27,617 pom.xml
def err = new StringBuffer() 2 File(s) 66,095 bytes
0 Dir(s) 15,503,597,568 bytes free
def out = new StringBuffer()
// could ignore/use Stream below ----- stderr -----
Return Code: 1
p.consumeProcessOutput(out, err) ls: *.xml: No such file or directory
def exitValue = p.waitFor()
if (err) println """----- stderr -----
Return Code: $exitValue
$err"""
if (out) println "----- stdout -----n$out"
JUL 2009 - 56

...Better Process Management
sout: tstfl.grvy
serr:
def sout = new StringBuffer()
def serr = new StringBuffer()
proc1 = 'tr -d o'.execute()
proc2 = 'tr -d e'.execute()
© ASERT 2006-2009
proc3 = 'tr -d i'.execute()
proc3.consumeProcessOutput(sout, serr)
proc1 | proc2 | proc3
[proc1, proc2].each{ it.consumeProcessErrorStream(serr) }
proc1.withWriter { writer ->
writer << 'testfile.groovy'
}
proc3.waitForOrKill(1000)
println 'sout: ' + sout
println 'serr: ' + serr
JUL 2009 - 57

Better Thread Management
Thread.start{ Hello from thread 2
4.times { Hello from thread 1
println 'Hello from thread 1' Hello from main thread
sleep 400 Hello from main thread
} Hello from thread 2
} Hello from thread 1
Thread.start{ Hello from main thread
© ASERT 2006-2009
5.times { Hello from thread 2
println 'Hello from thread 2' Hello from main thread
sleep 300 Hello from thread 1
} Hello from main thread
} Hello from thread 2
7.times { Hello from main thread
println 'Hello from main thread' Hello from thread 2
sleep 200 Hello from thread 1
} Hello from main thread
JUL 2009 - 58

Better SQL Manipulation...
import java.sql.Connection;
import java.sql.DriverManager;
import java.sql.Statement;
// ...
import java.sql.ResultSet;
finally {
import java.sql.SQLException;
// release database resources
close(rs); // close the ResultSet
public class JdbcJava {
close(stmt); // close the Statement
public static Connection getConnection() throws Exception {
close(conn); // close the Connection
String driver = "org.hsqldb.jdbcDriver";
}
String url = "jdbc:hsqldb:file:EMPDB";
}
String username = "sa"; String password = "";
Class.forName(driver);
private static void close(ResultSet rs) {
return DriverManager.getConnection(url, username, password);
try {
}
if (rs != null) rs.close();
} catch (SQLException e) {
© ASERT 2006-2009
public static void main(String[] args) {
Connection conn = null; e.printStackTrace();
Statement stmt = null; }
}
ResultSet rs = null;
try {
conn = getConnection(); private static void close(Statement st) {
stmt = conn.createStatement(); try {
String query = if (st != null) st.close();
"select id, lastname, firstname from Employees"; } catch (SQLException e) {
e.printStackTrace();
rs = stmt.executeQuery(query);
while (rs.next()) { }
System.out.println(rs.getString("id") + }
": " + rs.getString("firstname") +
private static void close(Connection cn) {
" " + rs.getString("lastname"));
} try {
if (cn != null) cn.close();
}
catch (Exception e) { } catch (SQLException e) {
// handle the exception e.printStackTrace();
e.printStackTrace(); }
}
System.err.println(e.getMessage());
} }
// ... JUL 2009 - 59

...Better SQL Manipulation...
import
import
java.sql.Connection;
java.sql.DriverManager; boilerplate
import java.sql.Statement;
// ...
import java.sql.ResultSet;
finally {
import java.sql.SQLException;
// release database resources
close(rs); // close the ResultSet
public class JdbcJava {
close(stmt); // close the Statement
public static Connection getConnection() throws Exception {
close(conn); // close the Connection
String driver = "org.hsqldb.jdbcDriver";
}
String url = "jdbc:hsqldb:file:EMPDB";
}
String username = "sa"; String password = "";
Class.forName(driver);
private static void close(ResultSet rs) {
return DriverManager.getConnection(url, username, password);
try {
}
if (rs != null) rs.close();
} catch (SQLException e) {
© ASERT 2006-2009
public static void main(String[] args) {
Connection conn = null; e.printStackTrace();
Statement stmt = null; }
}
ResultSet rs = null;
try {
conn = getConnection(); private static void close(Statement st) {
stmt = conn.createStatement(); try {
String query = if (st != null) st.close();
"select id, lastname, firstname from Employees"; } catch (SQLException e) {
e.printStackTrace();
rs = stmt.executeQuery(query);
while (rs.next()) { }
System.out.println(rs.getString("id") + }
": " + rs.getString("firstname") +
private static void close(Connection cn) {
" " + rs.getString("lastname"));
} try {
if (cn != null) cn.close();
}
catch (Exception e) { } catch (SQLException e) {
// handle the exception e.printStackTrace();
e.printStackTrace(); }
}
System.err.println(e.getMessage());
} }
// ... JUL 2009 - 60

...Better SQL Manipulation
import groovy.sql.Sql
def url = 'jdbc:hsqldb:file:EMPDB'
def username = 'sa'
def password = ''
© ASERT 2006-2009
def driver = 'org.hsqldb.jdbcDriver'
def db = Sql.newInstance(url, username, password, driver)
db.eachRow("SELECT id, firstname, lastname FROM Employees") {
println "$it.id: $it.firstname $it.lastname"
}
JUL 2009 - 61

More Details: Working with Databases
• Using standard SQL statements
import groovy.sql.Sql
def foo = 'cheese'
def db = Sql.newInstance("jdbc:mysql://localhost:3306/mydb",
"user", "pswd", "com.mysql.jdbc.Driver")
db.eachRow("select * from FOOD where type=${foo}") {
println "Gromit likes ${it.name}"
@ ASERT 2006-2009
}
• Using DataSets
import groovy.sql.Sql
def db = Sql.newInstance("jdbc:mysql://localhost:3306/mydb",
"user", "pswd", "com.mysql.jdbc.Driver")
def food = db.dataSet('FOOD')
def cheese = food.findAll { it.type == 'cheese' }
cheese.each { println "Gromit likes ${it.name}" }
JUL 2009 - 62

DataSets and Lazy Evaluation
athleteSet = db.dataSet('Athlete')
youngsters = athleteSet.findAll{ it.dateOfBirth > '1970-1-1'}
paula = youngsters.findAll{ it.firstname == 'Paula'}
println paula.sql
// =>
@ ASERT 2006-2009
// select * from Athlete where dateOfBirth > ? and firstname = ?
println paula.parameters
// =>
// [1970-1-1, Paula]
paula.each { println it.lastname } // database called here
// =>
// Radcliffe
JUL 2009 - 63

Better XML Manipulation...
<records> records.xml
<car name='HSV Maloo' make='Holden' year='2006'>
<country>Australia</country>
<record type='speed'>Production Pickup Truck with speed of 271kph</record>
</car>
© ASERT 2006-2009
<car name='P50' make='Peel' year='1962'>
<country>Isle of Man</country>
<record type='size'>Smallest Street-Legal Car at 99cm wide and 59 kg weight</record>
</car>
<car name='Royale' make='Bugatti' year='1931'>
<country>France</country>
<record type='price'>Most Valuable Car at $15 million</record>
</car>
</records>
JUL 2009 - 64

...Better XML Manipulation...
import org.w3c.dom.Document;
import org.w3c.dom.NodeList;
import org.w3c.dom.Node;
import org.xml.sax.SAXException;
import javax.xml.parsers.DocumentBuilderFactory;
import javax.xml.parsers.DocumentBuilder;
import javax.xml.parsers.ParserConfigurationException;
import java.io.File;
import java.io.IOException;
public class FindYearsJava {
public static void main(String[] args) {
© ASERT 2006-2009
DocumentBuilderFactory builderFactory = DocumentBuilderFactory.newInstance();
try {
DocumentBuilder builder = builderFactory.newDocumentBuilder();
Document document = builder.parse(new File("records.xml"));
NodeList list = document.getElementsByTagName("car");
for (int i = 0; i < list.getLength(); i++) {
Node n = list.item(i);
Node year = n.getAttributes().getNamedItem("year");
System.out.println("year = " + year.getTextContent());
}
} catch (ParserConfigurationException e) {
e.printStackTrace();
} catch (SAXException e) {
e.printStackTrace();
} catch (IOException e) {
e.printStackTrace();
}
}
}
JUL 2009 - 65

...Better XML Manipulation...
import org.w3c.dom.Document;
import org.w3c.dom.NodeList;
import org.w3c.dom.Node; boilerplate
import org.xml.sax.SAXException;
import javax.xml.parsers.DocumentBuilderFactory;
import javax.xml.parsers.DocumentBuilder;
import javax.xml.parsers.ParserConfigurationException;
import java.io.File;
import java.io.IOException;
public class FindYearsJava {
public static void main(String[] args) {
© ASERT 2006-2009
DocumentBuilderFactory builderFactory = DocumentBuilderFactory.newInstance();
try {
DocumentBuilder builder = builderFactory.newDocumentBuilder();
Document document = builder.parse(new File("records.xml"));
NodeList list = document.getElementsByTagName("car");
for (int i = 0; i < list.getLength(); i++) {
Node n = list.item(i);
Node year = n.getAttributes().getNamedItem("year");
System.out.println("year = " + year.getTextContent());
}
} catch (ParserConfigurationException e) {
e.printStackTrace();
} catch (SAXException e) {
e.printStackTrace();
} catch (IOException e) {
e.printStackTrace();
}
}
}
JUL 2009 - 66

...Better XML Manipulation
def records = new XmlParser().parse("records.xml")
records.car.each {
© ASERT 2006-2009
println "year = ${it.@year}"
}
year = 2006
year = 1962
year = 1931
JUL 2009 - 67

XML Processing Options
• Reading XML
– Special Groovy support: XmlParser, XmlSlurper, DOMCategory
• All support GPath, XmlSlurper features Lazy loading
– Or Groovy sugar for your current favorites: DOM, SAX, StAX,
DOM4J, JDom, XOM, XPath, XSLT, XQuery, etc.
• Creating XML
– Special Groovy support: MarkupBuilder and
© ASERT 2006-2009
StreamingMarkupBuilder
– Or again, enhanced syntax for your current favorites
• Updating XML
– Using above: read followed by create
– Can be done with XmlParser, XmlSlurper, DOMCategory
– Or with your Java favorites
• Verifying XML
– Also DTD, W3C XML Schema, Relax NG in a similar fashion to
Java mechanisms for these features
JUL 2009 - 68

More Details: XmlSlurper
def records = new XmlSlurper().parse("records.xml")
assert 3 == records.car.size() // 3 records in total
assert 10 == records.depthFirst().collect{ it }.size() // 10 nested nodes
// test properties of the first record
def firstRecord = records.car[0]
assert 'car' == firstRecord.name()
assert 'Holden' == firstRecord.@make.toString() && 'Australia' == firstRecord.country.text()
// 2 cars have an 'e' in the make
assert 2 == records.car.findAll{ it.@make.toString().contains('e') }.size()
@ ASERT 2006-2009
// 2 cars have an 'e' in the make
assert 2 == records.car.findAll{ it.@make =~ '.*e.*' }.size()
// makes of cars that have an 's' followed by an 'a' in the country
assert ['Holden', 'Peel'] == records.car.findAll{ it.country =~ '.*s.*a.*' }.@make.collect{ it.toString() }
// types of records
assert ['speed', 'size', 'price'] == records.depthFirst().grep{ it.@type != '' }.'@type'*.toString()
assert ['speed', 'size', 'price'] == records.'**'.grep{ it.@type != '' }.'@type'*.toString()
// check parent() operator
def countryOne = records.car[1].country
assert 'Peel' == countryOne.parent().@make.toString() && 'Peel' == countryOne.'..'.@make.toString()
// names of cars with records sorted by year
def names = records.car.list().sort{ it.@year.toInteger() }.'@name'*.toString()
assert ['Royale', 'P50', 'HSV Maloo'] == names
JUL 2009 - 69

Uniform Data Access
• Not just better SQL processing and better
XML processing but Uniform Data Access
– i.e. Data access to Objects, XML and SQL Databases
has more similarities than differences
– Fluent API regardless of data source
– Differences in detail about how to set up structures
@ ASERT 2006-2009
– Similarities in how to process data within resulting
structures
– Equivalent to LINQ API in .Net
JUL 2009 - 70

Object Data Access…
import java.text.SimpleDateFormat
class Athlete {
def firstname, lastname, gender, country, dateOfBirth
}
def asDate(dateStr) {
new SimpleDateFormat("yyyy-MM-dd").parse(dateStr)
}
@ ASERT 2006-2009
def athletes = [
new Athlete(firstname: 'Paul', lastname: 'Tergat',
dateOfBirth: '1969-06-17', gender: 'M', country: 'KEN'),
new Athlete(firstname: 'Khalid', lastname: 'Khannouchi',
dateOfBirth: '1971-12-22', gender: 'M', country: 'USA'),
new Athlete(firstname: 'Sammy', lastname: 'Korir',
dateOfBirth: '1971-12-12', gender: 'M', country: 'KEN'),
new Athlete(firstname: 'Ronaldo', lastname: 'da Costa',
dateOfBirth: '1970-06-07', gender: 'M', country: 'BRA'),
new Athlete(firstname: 'Paula', lastname: 'Radcliffe',
dateOfBirth: '1973-12-17', gender: 'F', country: 'GBR')
]
JUL 2009 - 71

…Object Data Access
def bornSince70 = {
asDate(it.dateOfBirth) > asDate('1970-1-1') }
def excludingKh = { it.lastname <= 'Kg' ||
it.lastname >= 'Ki' }
def byGenderDescThenByCountry = { a, b ->
a.gender == b.gender ?
a.country <=> b.country :
@ ASERT 2006-2009
b.gender <=> a.gender }
def someYoungsters = athletes.
findAll(bornSince70).
findAll(excludingKh).
sort(byGenderDescThenByCountry)
someYoungsters.each {
def name = "$it.firstname $it.lastname".padRight(25)
println "$name ($it.gender) $it.country $it.dateOfBirth"
}
JUL 2009 - 72

Xml Data Access…
import java.text.SimpleDateFormat
import com.thoughtworks.xstream.XStream
class Athlete {
String firstname, lastname, gender, country, dateOfBirth
}
def asDate(dateStr) { new SimpleDateFormat("yyyy-MM-dd").parse(dateStr) }
def athleteList = [
@ ASERT 2006-2009
new Athlete(firstname: 'Paul', lastname: 'Tergat',
dateOfBirth: '1969-06-17', gender: 'M', country: 'KEN'),
new Athlete(firstname: 'Khalid', lastname: 'Khannouchi',
dateOfBirth: '1971-12-22', gender: 'M', country: 'USA'),
new Athlete(firstname: 'Sammy', lastname: 'Korir',
dateOfBirth: '1971-12-12', gender: 'M', country: 'KEN'),
new Athlete(firstname: 'Ronaldo', lastname: 'da Costa',
dateOfBirth: '1970-06-07', gender: 'M', country: 'BRA'),
new Athlete(firstname: 'Paula', lastname: 'Radcliffe',
dateOfBirth: '1973-12-17', gender: 'F', country: 'GBR')
]
// create XML as input
def input = new XStream().toXML(athleteList)
JUL 2009 - 73

…Xml Data Access
def athletes = new XmlSlurper().parseText(input).Athlete
def bornSince70 = {
asDate(it.dateOfBirth.text()) > asDate('1970-1-1') }
def excludingKh = { it.lastname.text() <= 'Kg' ||
it.lastname.text() >= 'Ki' }
def byGenderDescThenByCountry = { a, b ->
a.gender.text() == b.gender.text() ?
@ ASERT 2006-2009
a.country.text() <=> b.country.text() :
b.gender.text() <=> a.gender.text() }
def someYoungsters = athletes.
findAll(bornSince70).findAll(excludingKh).list().
sort(byGenderDescThenByCountry)
someYoungsters.each {
def name = "$it.firstname $it.lastname".padRight(25)
println "$name ($it.gender) $it.country $it.dateOfBirth"
}
JUL 2009 - 74

Sql Data Access…
import groovy.sql.Sql
dbHandle = null
def getDb() {
if (dbHandle) return dbHandle
def source = new org.hsqldb.jdbc.jdbcDataSource()
source.database = 'jdbc:hsqldb:mem:GIA'
source.user = 'sa'
source.password = ''
dbHandle = new Sql(source)
@ ASERT 2006-2009
return dbHandle
}
db.execute '''
DROP INDEX athleteIdx IF EXISTS;
DROP TABLE Athlete IF EXISTS;
CREATE TABLE Athlete (
athleteId INTEGER GENERATED BY DEFAULT AS IDENTITY,
firstname VARCHAR(64),
lastname VARCHAR(64),
country VARCHAR(3),
gender CHAR(1),
dateOfBirth DATE
);
CREATE INDEX athleteIdx ON Athlete (athleteId);
'''
JUL 2009 - 75

…Sql Data Access…
def athleteList = [
[firstname: 'Paul', lastname: 'Tergat',
dateOfBirth: '1969-06-17', gender: 'M', country: 'KEN'],
[firstname: 'Khalid', lastname: 'Khannouchi',
dateOfBirth: '1971-12-22', gender: 'M', country: 'USA'],
[firstname: 'Sammy', lastname: 'Korir',
dateOfBirth: '1971-12-12', gender: 'M', country: 'KEN'],
@ ASERT 2006-2009
[firstname: 'Ronaldo', lastname: 'da Costa',
dateOfBirth: '1970-06-07', gender: 'M', country: 'BRA'],
[firstname: 'Paula', lastname: 'Radcliffe',
dateOfBirth: '1973-12-17', gender: 'F', country: 'GBR']
]
def athletes = db.dataSet('Athlete')
athleteList.each {a -> athletes.add(a)}
JUL 2009 - 76

…Sql Data Access
def bornSince70 = { it.dateOfBirth > '1970-1-1' }
def excludingKh = { it.lastname <= 'Kg' || it.lastname >= 'Ki' }
def someYoungsters = athletes.
findAll(bornSince70).
findAll(excludingKh).
sort { it.gender }.reverse().
sort { it.country }
@ ASERT 2006-2009
println someYoungsters.sql + 'n' + someYoungsters.parameters
someYoungsters.each {
def name = "$it.firstname $it.lastname".padRight(25)
println "$name ($it.gender) $it.country $it.dateOfBirth"
}
/* =>
select * from Athlete where dateOfBirth > ? and (lastname <= ? or lastname
>= ?) order by gender DESC, country
["1970-1-1", "Kg", "Ki"]
Ronaldo da Costa (M) BRA 1970-06-07
Sammy Korir (M) KEN 1971-12-12
Paula Radcliffe (F) GBR 1973-12-17 */
JUL 2009 - 77

Metaprogramming
• Runtime Metaprogramming
– Categories including DGM
– invokeMethod, methodMissing, getProperty
– GroovyInterceptable
– ExpandoMetaClass
© ASERT 2006-2009
• Compile-time Metaprogramming
– AST Macros
– Local and Global flavors based around annotations
– Reduced runtime overhead
– Several built-in annotations:
• @Immutable
• @Delegate
• @Singleton
JUL 2009 - 78

ExpandoMetaClass…
import static java.lang.Character.isUpperCase
String.metaClass.swapCase = {
delegate.collect { ch ->
isUpperCase(ch as char) ?
ch.toLowerCase() :
ch.toUpperCase()
}.join()
@ ASERT 2006-2009
}
println new Date().toString().swapCase()
// => sUN nOV 09 17:30:06 est 2008
List.metaClass.sizeDoubled = {-> delegate.size() * 2 }
LinkedList list = []
list << 1
list << 2
assert 4 == list.sizeDoubled()
JUL 2009 - 79

…ExpandoMetaClass
class Person {
String name
}
class MortgageLender {
def borrowMoney() {
"buy house"
}
@ ASERT 2006-2009
}
def lender = new MortgageLender()
Person.metaClass.buyHouse = lender.&borrowMoney
def p = new Person()
assert "buy house" == p.buyHouse()
JUL 2009 - 80

Grapes / Grab
// Google Collections example
import com.google.common.collect.HashBiMap
@Grab(group='com.google.collections',
module='google-collections',
version='1.0-rc2')
© ASERT 2006-2009
def getFruit() {
[ grape:'purple',
lemon:'yellow',
orange:'orange' ] as HashBiMap
}
assert fruit.lemon == 'yellow'
assert fruit.inverse().yellow == 'lemon'
JUL 2009 - 81

Better Design Patterns: Immutable...
• Java Immutable Class
– As per Joshua Bloch // ...
@Override
Effective Java public boolean equals(Object obj) {
if (this == obj)
public final class Punter { return true;
private final String first; if (obj == null)
private final String last; return false;
if (getClass() != obj.getClass())
public String getFirst() { return false;
return first; Punter other = (Punter) obj;
} if (first == null) {
@ ASERT 2006-2009
if (other.first != null)
public String getLast() { return false;
return last; } else if (!first.equals(other.first))
} return false;
if (last == null) {
@Override if (other.last != null)
public int hashCode() { return false;
final int prime = 31; } else if (!last.equals(other.last))
int result = 1; return false;
result = prime * result + ((first == null) return true;
? 0 : first.hashCode()); }
result = prime * result + ((last == null)
? 0 : last.hashCode()); @Override
return result; public String toString() {
} return "Punter(first:" + first
+ ", last:" + last + ")";
public Punter(String first, String last) { }
this.first = first;
this.last = last; }
}
// ...
JUL 2009 - 82

...Better Design Patterns: Immutable...
• Java Immutable Class boilerplate
– As per Joshua Bloch // ...
@Override
Effective Java public boolean equals(Object obj) {
if (this == obj)
public final class Punter { return true;
private final String first; if (obj == null)
private final String last; return false;
if (getClass() != obj.getClass())
public String getFirst() { return false;
return first; Punter other = (Punter) obj;
} if (first == null) {
@ ASERT 2006-2009
if (other.first != null)
public String getLast() { return false;
return last; } else if (!first.equals(other.first))
} return false;
if (last == null) {
@Override if (other.last != null)
public int hashCode() { return false;
final int prime = 31; } else if (!last.equals(other.last))
int result = 1; return false;
result = prime * result + ((first == null) return true;
? 0 : first.hashCode()); }
result = prime * result + ((last == null)
? 0 : last.hashCode()); @Override
return result; public String toString() {
} return "Punter(first:" + first
+ ", last:" + last + ")";
public Punter(String first, String last) { }
this.first = first;
this.last = last; }
}
// ...
JUL 2009 - 83

...Better Design Patterns: Immutable
@Immutable class Punter {
String first, last
@ ASERT 2006-2009
}
JUL 2009 - 84

Better Design Patterns: Singleton
class Calculator {
def total = 0
def add(a, b) { total++; a + b }
}
def INSTANCE = new Calculator()
Calculator.metaClass.constructor = { -> INSTANCE }
@ ASERT 2006-2009
def c1 = new Calculator()
def c2 = new Calculator()
@Singleton(lazy=true)
assert c1.add(1, 2) == 3 class X {
assert c2.add(3, 4) == 7 def getHello () {
"Hello, World!"
assert c1.is(c2) }
assert [c1, c2].total == [2, 2] }
println X.instance.hello
JUL 2009 - 85

Better Design Patterns: Delegate…
public Date getWhen() {
import java.util.Date;
return when;
}
public class Event {
private String title;
public void setWhen(Date when) {
private String url;
this.when = when;
private Date when;
}
public String getUrl() {
public boolean before(Date other) {
return url;
return when.before(other);
}
@ ASERT 2006-2009
}
public void setUrl(String url) {
public void setTime(long time) {
this.url = url;
when.setTime(time);
}
}
public String getTitle() {
public long getTime() {
return title;
return when.getTime();
}
}
public void setTitle(String title) {
public boolean after(Date other) {
this.title = title;
return when.after(other);
}
}
// ...
// ...
JUL 2009 - 86

…Better Design Patterns: Delegate…
public Date getWhen() {
import java.util.Date;
return when;
boilerplate }
public class Event {
private String title;
public void setWhen(Date when) {
private String url;
this.when = when;
private Date when;
}
public String getUrl() {
public boolean before(Date other) {
return url;
return when.before(other);
}
@ ASERT 2006-2009
}
public void setUrl(String url) {
public void setTime(long time) {
this.url = url;
when.setTime(time);
}
}
public String getTitle() {
public long getTime() {
return title;
return when.getTime();
}
}
public void setTitle(String title) {
public boolean after(Date other) {
this.title = title;
return when.after(other);
}
}
// ...
// ...
JUL 2009 - 87

…Better Design Patterns: Delegate
class Event {
String title, url
@Delegate Date when
}
@ ASERT 2006-2009
def gr8conf = new Event(title: "GR8 Conference",
url: "http://www.gr8conf.org",
when: Date.parse("yyyy/MM/dd", "2009/05/18"))
def javaOne = new Event(title: "JavaOne",
url: "http://java.sun.com/javaone/",
when: Date.parse("yyyy/MM/dd", "2009/06/02"))
assert gr8conf.before(javaOne.when)
JUL 2009 - 88

Functional Programming in Groovy
• Java functional programming goodness
– Normal OO methods
– Ability to have immutable types
– Some concurrency building blocks
• Closures for greater flexibility
@ ASERT 2006-2009
– Enabler for concurrency
• Lazy evaluation with Closures
– Built in to some libraries, e.g. data access
• Metaprogramming to enhance existing
libraries
• Third party Java libraries
– Functional Java, FunctionalJ, Commons Functor, Scala
JUL 2009 - 89

Functional Programming…
def fac(n) { n == 0 ? 1 : n * fac(n - 1) }
assert 24 == fac(4)
// define and use infinite streams
@ ASERT 2006-2009
def integers(n) { cons(n, { integers(n+1) }) }
def naturalnumbers = integers(1)
assert '1 2 3 4 5 6 7 8 9 10' ==
naturalnumbers.take(10).join(' ')
def evennumbers =
naturalnumbers.filter{ it % 2 == 0 }
assert '2 4 6 8 10 12 14 16 18 20' ==
evennumbers.take(10).join(' ')
JUL 2009 - 90

…Functional Programming…
import fj.data.Stream
//some metaprogramming to make fj mesh well with Groovy
Stream.metaClass.filter = { Closure c ->
delegate.filter(c as fj.F) }
Stream.metaClass.getAt = { n ->
delegate.index(n) }
@ ASERT 2006-2009
Stream.metaClass.getAt = { Range r ->
r.collect{ delegate.index(it)}}
Stream.metaClass.asList = { ->
delegate.toCollection().asList() }
def evens = Stream.range(0).filter{ it % 2 == 0 }
assert evens.take(5).asList() == [0, 2, 4, 6, 8]
assert (8..12).collect{ evens[it] } == [16, 18, 20, 22, 24]
assert evens[3..6] == [6, 8, 10, 12]
JUL 2009 - 91

…Functional Programming
import fj.data.Stream
import static fj.data.Stream.cons
// some metaprogramming to make Closures mesh well with
// fj functions and products
Stream.metaClass.filterTail = { Closure c ->
delegate.tail()._1().filter(c as fj.F) }
Stream.metaClass.static.cons = { h, Closure c ->
@ ASERT 2006-2009
delegate.cons(h, ['_1':c] as fj.P1) }
def sieve(nums) {
cons nums.head(), {
sieve nums.filterTail{ n -> n % nums.head() != 0 }
}
}
println sieve(Stream.range(2)).index(100) // => 547
JUL 2009 - 92

Enabling a functional style …
• Consider the Maximum Segment Sum
(MSS) problem
– Take a list of integers; the MSS is the maximum of the sums of
any number of adjacent integers
• Imperative solution:
@ ASERT 2006-2009
def numbers = [31,-41,59,26,-53,58,97,-93,-23,84]
def size = numbers.size()
def max = null
(0..<size).each { from ->
(from..<size).each { to ->
def sum = numbers[from..to].sum()
if (max == null || sum > max) max = sum
}
}
println "Maximum Segment Sum of $numbers is $max"

… Enabling a functional style …
• A first attempt at a more functional style:
def numbers = [31,-41,59,26,-53,58,97,-93,-23,84]
@ ASERT 2006-2009
def size = numbers.size()
def max = [0..<size, 0..<size].combinations().collect{
numbers[it[0]..it[1]].sum()
}.max()
println "Maximum Segment Sum of $numbers is $max"

… Enabling a functional style …
• An even more functional style
– A known solution using functional composition:
mss = max º sum* º (flatten º tails* º inits)
– Where inits and tails are defined as follows:
@ ASERT 2006-2009
letters = ['a', 'b', 'c', 'd']
assert letters.inits() == [ assert letters.tails() == [
['a'], ['d'],
['a', 'b'], ['c', 'd'],
['a', 'b', 'c'], ['b', 'c', 'd'],
['a', 'b', 'c', 'd'] ['a', 'b', 'c', 'd']
] ]

… Enabling a functional style
• An even more functional style
mss = max º sum* º (flatten º tails* º inits)
def segs = { it.inits()*.tails().sum() }
def solve = { segs(it)*.sum().max() }
def numbers = [31,-41,59,26,-53,58,97,-93,-23,84]
@ ASERT 2006-2009
println "Maximum Segment Sum of $numbers is ${solve numbers}"
Notes:
– sum() is one-level flatten in Groovy, flatten() is recursive
– Metaprogramming allowed us to enhance all Lists
List.metaClass {
inits{ (0..<delegate.size()).collect{ delegate[0..it] } }
tails{ delegate.reverse().inits() }
}
Source: http://hamletdarcy.blogspot.com/2008/07/groovy-vs-f-showdown-side-by-side.html

Concurrent Programming in Groovy
• Java concurrent programming goodness
– Normal OO methods
– Ability to have immutable types
– Some concurrency building blocks
• Process Enhancements
– AntBuilder and GDK methods
@ ASERT 2006-2009
• Closures for greater flexibility
– Enabler for concurrency
– Closure is Runnable and Callable
• Third party Java libraries
– Functional Java (Actors)
– Cascading.groovy subproject for Hadoop clusters
– Jetlang
– GridGain
– Groovy actors
JUL 2009 - 97

Fibonacci…
START = 8
END = 16
fib = {n -> n < 2 ? n : fib(n - 1) + fib(n - 2) }
(START..END).each {num ->
println "n:$num => ${fib(num)}"
}
@ ASERT 2006-2009
JUL 2009 - 98

…Fibonacci…
import java.util.concurrent.*
CUTOFF = 12 // not worth parallelizing for small n
THREADS = 100
println "Calculating Fibonacci sequence in parallel..."
serialFib = {n -> (n < 2) ? n : serialFib(n - 1) + serialFib(n - 2) }
pool = Executors.newFixedThreadPool(THREADS)
defer = {c -> pool.submit(c as Callable) }
fib = {n ->
@ ASERT 2006-2009
if (n < CUTOFF) return serialFib(n)
def left = defer { fib(n - 1) }
def right = defer { fib(n - 2) }
left.get() + right.get()
}
(8..16).each {n -> println "n=$n => ${fib(n)}" }
pool.shutdown()
JUL 2009 - 99

GParallelizer...
import static org.gparallelizer.actors.pooledActors.PooledActors.*
// create a new actor that prints out received messages
def console = actor {
loop {
react {message ->
println message
}
© ASERT 2006-2009
}
}
// start the actor and send it a message
console.start()
console.send('Message')
JUL 2009 - 100

...GParallelizer...
import java.util.concurrent.Future
// multiply numbers asynchronously
Asynchronizer.withAsynchronizer(5) {
Collection<Future> result =
[1, 2, 3, 4, 5].collectAsync{it * 10}
assertEquals(new HashSet([10, 20, 30, 40, 50]),
© ASERT 2006-2009
new HashSet((Collection) result*.get()))
}
// run multiple closures in parallel
Asynchronizer.withAsynchronizer {
assert AsyncInvokerUtil.doInParallel(
{calculateA()}, {calculateB()}
) == [10, 20]
}
JUL 2009 - 101

...GParallelizer
import static org.gparallelizer.dataflow.DataFlow.thread
final x = new DataFlowVariable()
final y = new DataFlowVariable()
final z = new DataFlowVariable()
thread {
z << ~x + ~y
© ASERT 2006-2009
println "Result: ${~z}"
}
thread {
x << 10
}
thread {
y << 5
}
JUL 2009 - 102

Better Testing
• Built-in support for: JUnit 3 & 4, TestNG
– A test is a first class citizen
• Built-in mocking
• Useful and Emerging Frameworks
– Easyb
© ASERT 2006-2009
– WebTest
– Selenium
– DbUnit
– FEST
– Spock
– GMock
JUL 2009 - 103

Built-in JUnit
• Groovy distribution includes JUnit
• Automatically invokes text runner
• Has some useful extensions
class GroovyMultiplierJUnit3Test extends GroovyTestCase { ..
void testPositives() {
@ ASERT 2006-2009
Time: 0.092
def testee = new GroovyMultiplier() OK (2 tests)
assertEquals "+ve multiplier error", 9, testee.triple(3)
assertEquals "+ve multiplier error", 12, testee.triple(4)
}
void testNegatives() {
def testee = new GroovyMultiplier()
assertEquals "-ve multiplier error", -12, testee.triple(-4)
}
}
JUL 2009 - 104

JUnit 4.5+
import org.junit.Test
import static org.junit.Assert.assertEquals
class ArithmeticTest {
@Test
void additionIsWorking() {
@ ASERT 2006-2009
assertEquals 4, 2+2
}
@Test(expected=ArithmeticException)
void divideByZero() {
println 1/0
}
}
JUL 2009 - 105

JUnit 4.5+ Parameterized Tests
import org.junit.Test
import org.junit.Before
import org.junit.runner.RunWith
import org.junit.runners.Parameterized
import org.junit.runners.Parameterized.*
@RunWith(Parameterized)
class GroovyMultiplierJUnit4Test { @Test void positivesFixed() {
def testee assert testee.triple(1) ==3
def param }
def expected
@ ASERT 2006-2009
@Test void positivesParameterized() {
@Parameters static data() { assert testee.triple(param) == expected
return (2..4).collect{ }
[it, it * 3] as Integer[]
} @Test void negativesParameterized() {
} assert testee.triple(-param) == -expected
}
GroovyMultiplierJUnit4Test(a, b) {
}
param = a
expected = b
}
@Before void setUp() {
testee = new GroovyMultiplier()
}
JUL 2009 - 106

JUnit 4.5+ Theories …
import org.junit.runner.*
import org.junit.experimental.theories.*
import static org.junit.Assume.assumeTrue
@RunWith(Theories)
class LanguageTheoryTest {
@DataPoint public static String java = 'Java'
@DataPoint public static String ruby = 'JRuby'
@DataPoint public static String python = 'Jython'
@ ASERT 2006-2009
@DataPoint public static String javascript = 'Rhino'
@DataPoint public static String groovy = 'Groovy'
@DataPoint public static String scala = 'Scala'
@DataPoint public static String csharp = 'C#'
def jvmLanguages = [java, ruby, python, groovy, scala, javascript]
def teamSkills = [
tom: [java, groovy, ruby],
dick: [csharp, scala, java, python],
harry: [javascript, groovy, java]
]
...
JUL 2009 - 107

… JUnit 4.5+ Theories
...
@Theory void everyoneKnowsJava() {
teamSkills.each { developer, skills ->
assert java in skills
}
}
@ ASERT 2006-2009
@Theory void teamKnowsEachJvmLanguage(String language) {
assumeTrue language in jvmLanguages
assert teamSkills.any { developer, skills ->
language in skills
}
}
}
JUnitCore.main(LanguageTheoryTest.name)
JUL 2009 - 108

Better Testing: TestNG
import ...
public class SimpleTest {
@BeforeClass
public void setUp() {
// code invoked when test is created
}
© ASERT 2006-2009
@Test(groups = [ "fast" ])
public void aFastTest() {
System.out.println("Fast test");
}
@Test(groups = [ "slow" ])
public void aSlowTest() {
System.out.println("Slow test");
}
}
JUL 2009 - 109

Better Testing: EasyB
• BDD, Rspec-like testing library
narrative 'segment flown', {
as_a 'frequent flyer'
i_want 'to accrue rewards points for every segment I fly'
so_that 'I can receive free flights for my dedication to the airline'
}
scenario 'segment flown', {
given 'a frequent flyer with a rewards balance of 1500 points'
@ ASERT 2006-2009
when 'that flyer completes a segment worth 500 points'
then 'that flyer has a new rewards balance of 2000 points'
}
scenario 'segment flown', {
given 'a frequent flyer with a rewards balance of 1500 points', {
flyer = new FrequentFlyer(1500)
}
when 'that flyer completes a segment worth 500 points', {
flyer.fly(new Segment(500))
}
then 'that flyer has a new rewards balance of 2000 points', {
flyer.pointsBalance.shouldBe 2000
}
} JUL 2009 - 110

Better Testing: Spock ...
© ASERT 2006-2009
JUL 2009 - 111

...Better Testing: Spock
@Speck
@RunWith(Sputnik)
class PublisherSubscriberSpeck {
def "events are received by all subscribers"() {
def pub = new Publisher()
def sub1 = Mock(Subscriber)
def sub2 = Mock(Subscriber)
pub.subscribers << sub1 << sub2
© ASERT 2006-2009
when:
pub.send("event")
then:
1 * sub1.receive("event")
1 * sub2.receive("event")
}
}
JUL 2009 - 112

Built-in Mocks for Groovy…
• Handle statics, explicit constructors, etc.
import groovy.mock.interceptor.MockFor
def mocker = new MockFor(Collaborator.class) // create the Mock support
mocker.demand.one(1..2) { 1 } // demand the 'one' method one or two times, returning 1
mocker.demand.two() { 2 } // demand the 'two' method exactly once, returning 2
@ ASERT 2006-2009
mocker.use { // start using the Mock
def caller = new Caller() // caller will call Collaborator
assertEquals 1, caller.collaborateOne() // will call Collaborator.one
assertEquals 1, caller.collaborateOne() // will call Collaborator.one
assertEquals 2, caller.collaborateTwo() // will call Collaborator.two
} // implicit verify for strict expectation here
JUL 2009 - 113

…Built-in Mocks for Groovy
import groovy.mock.interceptor.MockFor
class MockingTest extends GroovyTestCase {
def mock1 = new MockFor(Collaborator1) class Mocking {
def mock2 = new MockFor(Collaborator2) def method() {
def mock3 = new MockFor(Collaborator3) try {
private static final Closure DONTCARE = null new Collaborator1().method1()
private static final Closure PASS = {} new Collaborator2().method2()
private static final Closure FAIL = { } catch (Exception e) {
throw new RuntimeException() } new Collaborator3().method3()
void testSuccess() { }
check(PASS, PASS, DONTCARE) }
@ ASERT 2006-2009
} }
void testCollaborator1Fails() { class Collaborator1 {}
check(FAIL, DONTCARE, PASS)
class Collaborator2 {}
}
class Collaborator3 {}
void testCollaborator2Fails() {
check(PASS, FAIL, PASS)
}
private check(expected1, expected2, expected3){
if (expected1) mock1.demand.method1(expected1)
if (expected2) mock2.demand.method2(expected2)
if (expected3) mock3.demand.method3(expected3)
mock1.use { mock2.use { mock3.use {
new Mocking().method()
}}}
}
} JUL 2009 - 114

Better Testing: Mocking with Gmock...
• Method mocking: mockLoader.load("fruit").returns("apple")
• Exception mocking: mockLoader.load("unknown").raises(new
RuntimeException())
• Stub mocking: mockLoader.load("fruit").returns("apple").stub()
• Static method mocking: mockMath.static.random().returns(0.5)
• Property mocking: mockLoader.name.returns("loader")
• Constructor mocking: def mockFile = mock(File,
© ASERT 2006-2009
constructor('/a/path/file.txt'))
• Partial mocking: mock(controller).params.returns([id: 3])
• Times expectation:
mockLoader.load("fruit").returns("apple").atLeastOnce()
• Custom matcher: mockLoader.load(match{ it.startsWith("fru") })
• Strict ordering: ordered { ... }
• Optional support for Hamcrest matcher: mockLoader.put("test",
is(not(lessThan(5))))
• GMockController if you can't extend GMockTestCase in your test
JUL 2009 - 115

...Better Testing: Mocking with Gmock
import org.gmock.GMockTestCase
class LoaderTest extends GMockTestCase {
void testLoader(){
def mockLoader = mock()
© ASERT 2006-2009
mockLoader.load('key').returns('value')
play {
assertEquals "value", mockLoader.load('key')
}
}
}
JUL 2009 - 116

WebTest testing Web Sites
def ant = new AntBuilder()
def webtest_home = System.properties.'webtest.home'
ant.taskdef(resource:'webtest.taskdef') {
classpath {
pathelement(location:"$webtest_home/lib")
fileset(dir:"$webtest_home/lib", includes:"**/*.jar")
}
}
@ ASERT 2006-2009
def config_map = [:]
['protocol','host','port','basepath','resultfile',
'resultpath', 'summary', 'saveresponse','defaultpropertytype'].each {
config_map[it] = System.properties['webtest.'+it]
}
ant.testSpec(name:'groovy: Test Groovy Scripting at creation time') {
config(config_map)
steps {
invoke(url:'linkpage.html')
for (i in 1..10) {
verifyText(description:"verify number ${i} is on pages", text:"${i}")
}
}
}
JUL 2009 - 117

WebTest testing Emails
def ant = new AntBuilder()
def webtest_home = System.properties.'webtest.home'
ant.taskdef(resource:'webtest.taskdef'){
classpath(){
pathelement(location:"$webtest_home/lib")
fileset(dir:"$webtest_home/lib", includes:"**/*.jar")
}
}
@ ASERT 2006-2009
ant.testSpec(name:'Email Test'){
steps {
emailSetConfig(server:'localhost', password:'password',
username:'devteam@mycompany.org', type:'pop3')
emailStoreMessageId(subject:'/Build notification/',
property:'msg')
emailStoreHeader(property:'subject',
messageId:'#{msg}', headerName:'Subject')
groovy('''def subject = step.webtestProperties.subject
assert subject.startsWith('Build notification')''')
emailMessageContentFilter(messageId:'#{msg}')
verifyText(text:'Failed build')
}
}
JUL 2009 - 118

SOAP Client and Server
class MathService {
double add(double a, double b) {
a + b
}
double square(double c) {
c * c
}
}
@ ASERT 2006-2009
import groovy.net.soap.SoapServer
def server = new SoapServer('localhost', 6789)
server.setNode('MathService')
server.start()
import groovy.net.soap.SoapClient
def math = new SoapClient('http://localhost:6789/MathServiceInterface?wsdl')
assert math.add(1.0, 2.0) == 3.0
assert math.square(3.0) == 9.0
JUL 2009 - 119

Better Testing: SoapUI
• Tool for testing Web Services has a built-
in Groovy editor for custom steps
@ ASERT 2006-2009
JUL 2009 - 120

Integration with Spring...
// traditional approach using a beans xml file
import org.springframework.context.support.ClassPathXmlApplicationContext
def ctx = new ClassPathXmlApplicationContext('calcbeans.xml')
def calc = ctx.getBean('calcBean')
println calc.doAdd(3, 4) // => 7
@ ASERT 2006-2009
// using BeanBuilder
def bb = new grails.spring.BeanBuilder()
bb.beans {
adder(AdderImpl)
calcBean(CalcImpl2) { adder = adder }
}
def ctx = bb.createApplicationContext()
def calc = ctx.getBean('calcBean')
println calc.doAdd(3, 4) // => 7
JUL 2009 - 121

...Integration with Spring
// using annotations
import org.springframework.stereotype.Component
@Component class AdderImpl {
def add(x, y) { x + y }
}
import org.springframework.beans.factory.annotation.Autowired
import org.springframework.stereotype.Component
@ ASERT 2006-2009
@Component class CalcImpl3 {
@Autowired private AdderImpl adder
def doAdd(x, y) { adder.add(x, y) }
}
import org.springframework.context.support.GenericApplicationContext
import org.springframework.context.annotation.ClassPathBeanDefinitionScanner
def ctx = new GenericApplicationContext()
new ClassPathBeanDefinitionScanner(ctx).scan('') // scan root package for components
ctx.refresh()
def calc = ctx.getBean('calcImpl3')
println calc.doAdd(3, 4) // => 7
JUL 2009 - 122

Dependency Injection: Guice
import com.google.inject.*
@ImplementedBy(CalculatorImpl)
interface Calculator {
def add(a, b)
}
@Singleton
class CalculatorImpl implements Calculator {
private total = 0
© ASERT 2006-2009
def add(a, b) { total++; a + b }
def getTotalCalculations() { 'Total Calculations: ' + total }
String toString() { 'Calc: ' + hashCode()}
}
class Client {
@Inject Calculator calc
// ...
}
def injector = Guice.createInjector()
// ...
JUL 2009 - 123

A taste of Grails
• Grails has three properties that increase
developer productivity significantly when
compared to traditional Java web frameworks:
– No XML configuration
– Ready-to-use development environment
– Functionality available through mixins
@ ASERT 2006-2009
JUL 2009 - 124

JUL 2009 - 125
RDBMS, Messaging, Web Services, Security
…
Grails Model
Radeox/FCK
POJOs
POGOs
Wicket
GORM
JMS/Acegi
Captcha
Architecture
Xfire/REST
Grails Controller
Java Runtime
DWR/GWT
Plugins
Controllers
OpenLaszlo
…
Groovy
Quartz
Hibernate
JSP Page
Java Libraries
Grails Views
Spring
GSP Page
Groovlet JDBC/HSQL
Jetty
HTML/Ajax Browser
…
Textmate
JDK
Ant
Netbeans
Eclipse
IntelliJ
@ ASERT 2006-2009

Web framework
• Controllers
class BookController {
def list = {
[ books: Book.findAll() ]
}
}
grails create-controller
@ ASERT 2006-2009
• Views
<html>
<head>
<title>Our books</title>
</head>
<body>
<ul>
<g:each it="books">
<li>${it.title} (${it.author.name})</li>
</g:each>
</ul>
</body>
</html>
JUL 2009 - 126

Persistence
• Model
grails create-domain-class
class Book {
Long id
Long version
String title
@ ASERT 2006-2009
Person author
}
• Methods
def book = new Book(title:"The Da Vinci Code", author:Author.findByName("Dan Brown"))
book.save()
def book = Book.find("from Book b where b.title = ?", [ 'The Da Vinci Code' ])
def books = Book.findAll()
def book = Book.findByTitleLike("%Da Vinci%")
def book = Book.findWhere(title:"The Da Vinci Code")
JUL 2009 - 127

Project Structure
+ PROJECT_HOME
+ grails-app Main Grails resources
+ conf
+ controllers
+ domain
+ i18n
@ ASERT 2006-2009
Jar archive libraries + services
+ taglib
+ views Additional Spring configuration
+ lib
+ spring
+ hibernate Additional Hibernate mapping
+ src
Java sources + web-app
Web resources e.g. CSS, JavaScript etc.
JUL 2009 - 128

More Information: on the web
• Web sites
– http://groovy.codehaus.org
– http://grails.codehaus.org
– http://pleac.sourceforge.net/pleac_groovy (many examples)
– http://www.asert.com.au/training/java/GV110.htm (workshop)
• Mailing list for users
@ ASERT 2006-2009
– user@groovy.codehaus.org
• Information portals
– http://www.aboutgroovy.org
– http://www.groovyblogs.org
• Documentation (1000+ pages)
– Getting Started Guide, User Guide, Developer Guide, Testing
Guide, Cookbook Examples, Advanced Usage Guide
• Books
– Several to choose from ...
JUL 2009 - 129

More Information: Groovy in Action
@ ASERT 2006-2009
Second edition of GinA, ‘ReGinA’ now under development JUL 2009 - 130