first steps


for the newbies to groovy and grails
There are many things for the experts, butfor the newbies, sometimes it´d a hard time, when justa little brick is missing.

I try to show may way to groovy and grails

Sunday, 27 May, 2012

Groovy and creating of PDF (iText)

For some next test, I want to create a PDF
(later with data of the database)

It´s the first time, I combine a Java-Lib with groovy.
It seems, that iText is state of the the art for producing PDFs.

I found only few combination at google: Groovy and iText.
This link lead to empty pages (but the contents looked good)

This one was a great help.

Before the information is lost, I copy it to here.

It was very easy, strait forward. Copy th download of  iText to groovy/lib
and the imports will the solved. Some magic with Java for the newbee,
but it realy works.

goovy pdf.groovy  and the PDF-File is created


I followed some Groovy talks during Devoxx 2011 and I was impressed by the language, but I haven’t been able to test it out, up until now. As with Jython, it was pretty easy to install and to import iText into a project. It’s actually the same process as you would import a jar into a Java project. Assuming that you’re able to do that without instructions, so here’s the Hello World code for Groovy:

02 * Created on 28-dec.-2011
03 * Creating a simple Hello World pdf in Groovy using iText 5.1.3
04 * @author: iText
05 */
06import com.itextpdf.text.Document
07import com.itextpdf.text.Paragraph
08import com.itextpdf.text.pdf.PdfWriter
10// step 1
11def document = new Document()
12println("Document Created")
14// step 2
15PdfWriter.getInstance(document, new FileOutputStream("document.pdf"))
16println("PdfWriter Created")
18// step 3
20println("Document Opened")
22// step 4
23document.add(new Paragraph("Hello Groovy!"))
24println("Content Added")
26// step 5
28println("Document Closed")

As you can see, the code is straightforward and simple and it looks pretty much like Jython. I prefer Groovy over Jython because it’s much faster and actually feels like a JVM language and not like a port of another language. Still a lot of love for Python though.

Sunday, 22 April, 2012

comparison groovy and other languages

A very nice comparison, Groovy and other languages


Sunday, 15 April, 2012

groovy: how to compile and run a groovy-pogramm stand alone


as groovy is interpreted (better: compiled every time) as it runs,
I found a nice idea, to compile the programm and let it run.

for the complete solution, look at  :

very easy going

 fest@maxdata:~/intranet/htdocs/gutacht/versand> groovy wrapper.groovy -c -m pdf
     [echo] Compiling pdf.groovy
      [jar] Building jar: /home/fest/intranet/htdocs/gutacht/versand/pdf.jar
     [echo] Run script using: 'java -jar pdf.jar ...'
fest@maxdata:~/intranet/htdocs/gutacht/versand> java -jar pdf.jar 1 2 3
Anzahl Argumente 3
Usage:  pdf  Gutachten-nr  Datei  Zeile1  Zeile
This is the wrapper.groovy
 * Copyright 2002-2007 the original author or authors.
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * See the License for the specific language governing permissions and
 * limitations under the License.

 * Wrap a script and groovy jars to an executable jar
def cli = new CliBuilder()
cli.h( longOpt: 'help', required: false, 'show usage information' )
cli.d( longOpt: 'destfile', argName: 'destfile', required: false, args: 1, 'jar destintation filename, defaults to {mainclass}.jar' )
cli.m( longOpt: 'mainclass', argName: 'mainclass', required: true, args: 1, 'fully qualified main class, eg. HelloWorld' )
cli.c( longOpt: 'groovyc', required: false, 'Run groovyc' )

def opt = cli.parse(args)
if (!opt) { return }
if (opt.h) {

def mainClass = opt.m
def scriptBase = mainClass.replace( '.', '/' )
def scriptFile = new File( scriptBase + '.groovy' )
if (!scriptFile.canRead()) {
   println "Cannot read script file: '${scriptFile}'"
def destFile = scriptBase + '.jar'
if (opt.d) {
  destFile = opt.d

def ant = new AntBuilder()

if (opt.c) {
  ant.echo( "Compiling ${scriptFile}" ) [ scriptFile ] as String[] )

def GROOVY_HOME = new File( System.getenv('GROOVY_HOME') )
if (!GROOVY_HOME.canRead()) {
  ant.echo( "Missing environment variable GROOVY_HOME: '${GROOVY_HOME}'" )

ant.jar( destfile: destFile, compress: true, index: true ) {
  fileset( dir: '.', includes: scriptBase + '*.class' )

  zipgroupfileset( dir: GROOVY_HOME, includes: 'embeddable/groovy-all-*.jar' )
  zipgroupfileset( dir: GROOVY_HOME, includes: 'lib/commons*.jar' )
  // add more jars here

  manifest {
    attribute( name: 'Main-Class', value: mainClass )

ant.echo( "Run script using: \'java -jar ${destFile} ...\'" )

groovy: command line parameter / argument handling


used from C, but there is not argc, argv.


args (Arry og arguments) and
args.size()  number of arguments

Like this

if ( args.size() != 4  )
  { println "Anzahl Argumente " + args.size()
    println "Usage:  pdf  Gutachten-nr  Datei  Zeile1  Zeile"

def nr = args[0]
def datei = args[1]
def zeile1 = args[2]
def zeile2 = args[3]

Wednesday, 11 April, 2012

groovy first example: Hello World

the must in every language, teh hello world

println "hello World"

nothing more than this.

make it more complicate
def hello="hello"
def world="world"
println hello+" " +world
println "$hello $world"
Put this in a file  hello.groovy

and command
groovy hello.groovy 
So nice feature,
no ;
no main
no $  (only in the strings)
no ()   after the function println, as long, as all is cllear enough 

And the "def" gives a little more clarity,
other than in PHP,where every varibale, you write $abc or $abd
are varibales implizit declared.

Installing groovy

Look  at the introduction at

Short abstract
These instructions describe how to install a binary distribution of Groovy.
  • first, Download a binary distribution of Groovy and unpack it into some file on your local file system
  • set your GROOVY_HOME environment variable to the directory you unpacked the distribution
  • add GROOVY_HOME/bin to your PATH environment variable
  • set your JAVA_HOME environment variable to point to your JDK.

It did it on windows,

first test is a DOS command-windows and there print  "groovy -version" and you see,
wether all is fine and installed

Grails: first steps

What are the first steps to grails heaven ? (groovy) (Grails, comes with groovy included)

a nice IDE (STS) comes comes

How to install grails, an excellent leed in grails  (still unter construction)

But in the next step, we start with groovy.

some more reference to the newbie