Post on 09-May-2015
description
INTRODUCTIE IN GROOVY
AMIS – 26 november 2012
private String name;
public void setName(String name) {
this.name = name;
}
public String getName() {
return name;
}
OVER JAVA
• Academisch
• Uitgewerkt concept, Super uitgespecificeerd
• Bewezen
• Performant, Platform onafhankelijk
• Robust, Secure (?)
• Antiek
• Modern in 1995
• Vergelijk: C#, Python, Ruby, JavaScript, Smalltalk, Go
• Autistisch
import java.io.*;
import java.math.BigDecimal;
import java.net.*;
import java.util.*;
OVER JAVA – VERGELIJKING
Java
public class Pet {
private PetName name;
private Person owner;
public Pet(PetName name, Person owner) {
this.name = name;
this.owner = owner;
}
public PetName getName() {
return name;
}
public void setName(PetName name) {
this.name = name;
}
public Person getOwner() {
return owner;
}
public void setOwner(Person owner) {
this.owner = owner;
}
}
C#
public class Pet
{
public PetName Name { get; set; }
public Person Owner { get; set; }
}
OVER JAVA – VERGELIJKING
Java
Map<String, Integer> map =
new HashMap<String, Integer>();
map.put("een", 1);
map.put("twee", 2);
map.put("drie", 3);
map.put("vier", 4);
map.put("vijf", 5);
map.put("zes", 6);
Python
map = {'een':1, 'twee':2, 'drie':3,
'vier':4, 'vijf':5, 'zes':6}
OVER JAVA – VERGELIJKING
Java
FileInputStream fis = null;
InputStreamReader isr = null;
BufferedReader br = null;
try {
fis = new FileInputStream("file.txt");
isr = new InputStreamReader(fis);
br = new BufferedReader(isr);
String line;
while ((line = br.readLine()) != null) {
System.out.println(line);
}
} catch (IOException e) {
throw new RuntimeException(e);
} finally {
if (br != null)
try { br.close();
} catch (IOException e) { }
if (isr != null)
try { isr.close();
} catch (IOException e) { }
if (fis != null)
try { fis.close();
} catch (IOException e) { }
}
Python
with open('file.txt', 'r') as f:
for line in f:
print line,
OVER GROOVY
• Sinds: 2003
• Door: James Strachan
• Target: Java ontwikkelaars
• Basis: Java
• Plus: “Al het goede” van Ruby, Python en Smalltalk
• Apache Licence
• Uitgebreide community
• Ondersteund door SpringSource (VMWare)
• “The most under-rated language ever”
• “This language was clearly designed by very, very lazy
programmers.”
OVER GROOVY
• Draait in JVM
• Groovy class = Java class
• Perfecte integratie met Java
HELLO WORLD - JAVA
public class HelloWorld {
private String name;
public void setName(String name) {
this.name = name;
}
public String getName() {
return name;
}
public String greet() {
return "Hello " + name;
}
public static void main(String[] args) {
HelloWorld helloWorld = new HelloWorld();
helloWorld.setName("Groovy");
System.out.println(helloWorld.greet());
}
}
HELLO WORLD - GROOVY
public class HelloWorld {
private String name;
public void setName(String name) {
this.name = name;
}
public String getName() {
return name;
}
public String greet() {
return "Hello " + name;
}
public static void main(String[] args) {
HelloWorld helloWorld = new HelloWorld();
helloWorld.setName("Groovy");
System.out.println(helloWorld.greet());
}
}
HELLO WORLD - GROOVY
public class HelloWorld {
private String name;
public void setName(String name) {
this.name = name;
}
public String getName() {
return name;
}
public String greet() {
return "Hello " + name;
}
public static void main(String[] args) {
HelloWorld helloWorld = new HelloWorld();
helloWorld.setName("Groovy");
System.out.println(helloWorld.greet());
}
}
HELLO WORLD - GROOVY
public class HelloWorld {
String name;
public String greet() {
return "Hello " + name;
}
public static void main(String[] args) {
HelloWorld helloWorld = new HelloWorld();
helloWorld.setName("Groovy");
System.out.println(helloWorld.greet());
}
}
HELLO WORLD - GROOVY
public class HelloWorld {
String name;
public String greet() {
return "Hello " + name;
}
public static void main(String[] args) {
HelloWorld helloWorld = new HelloWorld();
helloWorld.setName("Groovy");
System.out.println(helloWorld.greet());
}
}
HELLO WORLD - GROOVY
class HelloWorld {
String name
def greet() {
return "Hello " + name
}
static main(args) {
def helloWorld = new HelloWorld()
helloWorld.setName("Groovy")
System.out.println(helloWorld.greet())
}
}
HELLO WORLD - GROOVY
class HelloWorld {
String name
def greet() {
return "Hello " + name
}
static main(args) {
def helloWorld = new HelloWorld()
helloWorld.setName("Groovy")
System.out.println(helloWorld.greet())
}
}
name:"Groovy")
HELLO WORLD - GROOVY
class HelloWorld {
String name
def greet() { "Hello " + name }
static main(args) {
def helloWorld = new HelloWorld(name:"Groovy")
println(helloWorld.greet())
}
}
HELLO WORLD - GROOVY
class HelloWorld {
String name
def greet() { "Hello " + name }
static main(args) {
def helloWorld = new HelloWorld(name:"Groovy")
println(helloWorld.greet())
}
}
HELLO WORLD - GROOVY
class HelloWorld {
def name
def greet() { "Hello $name" }
}
def helloWorld = new HelloWorld(name:"Groovy")
println helloWorld.greet()
HELLO WORLD - GROOVY
public class HelloWorld {
private String name;
public void setName(String name) {
this.name = name;
}
public String getName() {
return name;
}
public String greet() {
return "Hello " + name;
}
public static void main(String[] args) {
HelloWorld helloWorld = new HelloWorld();
helloWorld.setName("Groovy");
System.out.println(helloWorld.greet());
}
}
class HelloWorld {
def name
def greet() { "Hello $name" }
}
def helloWorld = new HelloWorld(name:"Groovy")
println helloWorld.greet()
GROOVY CONSOLE
GROOVY INTEGRATION
• Als Programmeertaal
– Compileert design-time
– Configuratie in Ant build script
GROOVY INTEGRATION - ANT
<?xml version="1.0" encoding="windows-1252" ?>
<project xmlns="antlib:org.apache.tools.ant" name="Project1">
...
<path id="groovy.lib" location="${workspace.dir}/groovy-all-2.0.1.jar"/>
...
<taskdef name="groovyc" classname="org.codehaus.groovy.ant.Groovyc“
classpathref="groovy.lib"/>
...
<target name="compile">
<groovyc srcdir="${src.dir}" destdir="${output.dir}">
<javac source="1.6" target="1.6"/>
</groovyc>
</target>
...
</project>
GROOVY INTEGRATION
• Als Programmeertaal
– Compileert design-time
– Configuratie in Ant build script
• Als Scripttaal
– Compileert run-time
• (Groovy compiler is geschreven in Java)
GROOVY INTEGRATION - SCRIPTING
GroovyShell gs = new GroovyShell();
Object result = gs.evaluate("...");
GROOVY FEATURES
• Native syntax
– Lists
def list = [1, 2, 3, 4]
– Maps:
def map = [nl: 'Nederland', be: 'Belgie']
assert map['nl'] == 'Nederland'
&& map.be == 'Belgie'
– Ranges:
def range = 11..36
– Regular Expressions
assert 'abc' ==~ /.\wc/
GROOVY FEATURES
• Native syntax (vervolg)
– GStrings
"Hello $name, it is now: ${new Date()}"
– Multiline Strings
def string = """Dit is regel 1.
Dit is regel 2."""
– Multiple assignment
def (a, b) = [1, 2]
(a, b) = [b, a]
def (p, q, r, s, t) = 1..5
GROOVY FEATURES
• New Operators
– Safe navigation (?.)
person?.adress?.streetname
in plaats van
person != null ? (person.getAddress() != null ?
person.getAddress().getStreetname() : null) :
null
– Elvis (?:)
username ?: 'Anoniem'
– Spaceship (<=>)
assert 'a' <=> 'b' == -1
GROOVY FEATURES
• Operator overloading
– Uitgebreid toegepast in GDK, voorbeelden:
def list = ['a', 'b', 1, 2, 3]
assert list + list == list * 2
assert list - ['a', 'b'] == [1, 2, 3]
new Date() + 1 // Een date morgen
GROOVY FEATURES
• Smart conversion (voorbeelden)
– to Numbers
def string = '123'
def nr = string as int
assert string.class.name == 'java.lang.String'
assert nr.class.name == 'java.lang.Integer'
– to Booleans (Groovy truth)
assert "" as boolean == false
if (string) { ... }
– to JSON
[a:1, b:2] as Json // {"a":1,"b":2}
– to interfaces
GROOVY FEATURES
• Closures
– (Anonieme) functie
• Kan worden uitgevoerd
• Kan parameters accepteren
• Kan een waarde retourneren
– Object
• Kan in variabele worden opgeslagen
• Kan als parameter worden meegegeven
– Voorbeeld:
new File('file.txt').eachLine({ line ->
println line
})
– Kan variabelen buiten eigen scope gebruiken
it
GROOVY FEATURES
• Groovy SQL
– Zeer mooie interface tegen JDBC
– Gebruikt GStrings voor queries
– Voorbeeld:
def search = 'Ki%'
def emps = sql.rows ( """select *
from employees
where first_name like $search
or last_name like $search""" )
GROOVY FEATURES
• Builders
– ‘Native syntax’ voor het opbouwen van:
• XML
• GUI (Swing)
• Json
• Ant taken
• …
– Op basis van Closures
GROOVY QUIZ
• Geldig?
def l = [ [a:1, b:2], [a:3, b:4] ]
def (m, n) = l
class Bean { def id, name }
new Bean().setName('Pieter')
[id:123, name:'Pieter'] as Bean
geef mij nu een kop koffie, snel
def
GROOVY FEATURES
• Categories
– Tijdelijke DSL (domain specific language)
– Breidt (bestaande) classes uit met extra functies
– Voorbeeld:
use(TimeCategory) {
newDate = (1.month + 1.week).from.now
}
GROOVY FEATURES
• (AST) Transformations
– Verder reduceren boiler plate code
– Enkele patterns worden meegeleverd, o.a.:
• @Singleton
• @Immutable / @Canonical
• @Lazy
• @Delegate (multiple inheritance!)
GROOVY CASES
• Java omgeving
– Als je werkt met: (ook in productie)
• Beans
• XML / HTML / JSON
• Bestanden / IO algemeen
• Database via JDBC
• Hardcore Java classes (minder boilerplate)
• DSL
• Rich clients (ook JavaFX)
– Functioneel programmeren in Java
– Prototyping
– Extreme dynamic classloading
• Shell scripting
GROOVY HANDSON
“ADF SCRIPTENGINE”
• Combinatie van:
– ADF
– Groovy
• met wat nieuwe constructies (“omdat het kan”)
• Features
– Programmaflow in Groovy
– Builder syntax voor tonen schermen in ADF
• Control state is volledig serialiseerbaar (high availability enzo)
– Bindings (à la EL ValueBindings)
– Mooie API (à la Grails) richting Model (bijv. ADF BC,
WebServices, etc...)
“ADF SCRIPTENGINE”
• Voorbeeld script
– Handmatig aanvullen lege elementen in een XML fragment
GROOVY TEASER
• Method parameters with defaults
• Method with named parameters
• Creating Groovy API’s
• Runtime meta-programming
• Compile-time meta-programming
• Interceptors
• Advanced OO (Groovy interfaces)
• GUI’s
• …