This document provides examples of using Groovy for common tasks like copying files, parsing RSS/Atom feeds, running a simple web server, and parsing command line options. It demonstrates how to: 1) Copy files in Groovy using various methods like left-shifting a file into another, reading/writing bytes, or using Ant's copy task. 2) Parse RSS, RDF, and Atom feeds by handling each format's node names and extracting item titles. 3) Run a basic HTTP server on port 8080 that returns a "success" message or serves a template file. 4) Define and parse command line options using a CliBuilder to output parameters and settings.

2. !
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3. !
http://groups.google.com/group/jggug-summer-2009
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jggug-summer-2009@googlegroups.com
subject /
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4. !
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5. !
! JAVA_HOME GROOVY_HOME
! $GROOVY_HOME/bin
!
% groovy -v
Groovy Version: 1.6.4 JVM: 1.5.0_19

6. !
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–
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8. !
! Input/OutputStream Reader/Writer
% groovy filecopy <srcfile> <destfile>

9. !
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File#getText(), readBytes(), append(), leftShift()...
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!
String#execute()
groovy.util.AntBuilder

10. java.io.File
src = new File(args[0])
dest = new File(args[1])
dest << src.text
dest.leftShift(src.getText())
leftShift append
GDK

11. src = new File(args[0])
dest = new File(args[1])
dest << src.readBytes()
OutOfMemoryError

12. proc = "cp ${args[0]} ${args[1]}".execute()
proc.waitFor()
waitFor()
cp
OK UNIX cp

13. ant = new AntBuilder()
ant.copy(file:args[0], tofile:args[1])
Ant copy
OK

14. !
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% groovy feedreader <URL>

15. !
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16. <rdf:RDF>
<channel>
...
</channel>
<item>
<title>...</title>
...
</item>
<item>
<title>...</title>
...
</item>
</rdf:RDF>

17. <rss>
<channel>
...
<item>
<title>...</title>
...
</item>
<item>
<title>...</title>
...
</item>
</channel>
</rss>

18. <feed>
...
<entry>
<title>...</title>
...
</entry>
<entry>
<title>...</title>
...
</entry>
</feed>

19. root = new XmlSlurper().parse(args[0])
switch(root.name()) {
case 'RDF' : nodes = root.item; break
case 'rss' : nodes = root.channel.item; break
case 'feed': nodes = root.entry; break
}
nodes.each { println it.title }

20. !
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% groovy -l 8080 httpserver

21. ! -l <port>
!
!
line
! return
'success'

22. if (!line) {
println 'HTTP/1.0 200 OK'
println 'Content-Type: text/htmln'
println new File('message.html').text
return 'success'
}
If

23. !
% groovy -l 8080 httpserver

24. !
!

25. import groovy.text.SimpleTemplateEngine as STE
if (!line) {
println 'HTTP/1.0 200 OK'
println 'Content-Type: text/htmln'
text = new File('message.html').text
println new STE().createTemplate(text).make()
return 'success'
}

26. !
!
! http://ja.doukaku.org/205/
% groovy cmdopt <arguments...>

27. cli = new CliBuilder(usage:'cmdopt -o [-q] [-d{0|1|2}]
[ ...]')
cli.with {
o longOpt:'output', 'set output', required:true
q longOpt:'quote', 'set quote'
d longOpt:'debug', 'set debug level', args:1,
argName:'level'
}
if (!(opt = cli.parse(args))) die 'bad command line'
params = opt.arguments()
if (params.size() < 1) die 'parameter must be specified'
level = opt.d ? opt.d as int : 0
if (!(level in 0..2)) die 'debug level must be in 0-2'

28. println '[ ]'
println "o(output): ${opt.o ? 'ON' : 'OFF'}"
println "q(quote): ${opt.q ? 'ON' : 'OFF'}"
println "d(debug): $level"
println 'n[ ]'
println " : ${params.size()}"
params.eachWithIndex { param, i -> println "${i + 1}:
$param" }
def die(msg) {
cli.writer.println "error: $msg"
cli.usage()
System.exit 1
}