Introduction to Apache Commons presented at ApacheCon US 2008

1. Apache
Commons
Torsten Curdt
don’t re-invent the wheel

2. Why are you a
Developer?

3. Creating & Building

4. That is a problem!

5. The journey
is the goal.

6. Use vs Build

7. A Story of Re-use

8. •Faster
•Better designed
•Less time
•Smaller team

9. Original
Re-Impl
0 5,000 10,000 15,000 20,000 25,000
hours

10. 20,000 hours

11. 7x

12. 5x

13. How did we do it?

14. Re-use to Excel

15. Know your libraries!

16. Heritage

17. Charter
“Creation of small re-useable
components that can be used across
projects. They are supposed to have as
few dependencies as possible, meant
to be well tested and compatible with
the current de-facto standard version of
the JDK”

18. Growth
Sandbox
Proper Dormant

19. Project Stats
60
Dormant
Proper
37 Sandbox
45
30 37
15
18
0
Active Inactive

20. Proper

21. Collections
Map map = new CaseInsensitiveMap();
map.put(quot;Onequot;, quot;Onequot;);
map.get(quot;ONEquot;);
Map colorMap = MapUtils.toMap(new String[][] {{
{quot;redquot;, quot;#FF0000quot;},
{quot;greenquot;, quot;#00FF00quot;},
{quot;bluequot;, quot;#0000FFquot;}
});

22. Primitives
ArrayByteList list = new ArrayByteList();
list.add(byte);
list.removeElementAt(index);
byte[] bytes = list.toArray();

23. IO
InputStream in;
OutputStream out;
IOUtils.copy(in, out);
...
byte[] data = IOUtils.toByteArray(in);

24. Lang
String s = “Apache Jakarta Commons”;
StringUtils.right(s, 7); // “Commons”
String n = “0”;
StringUtils.leftPad(s, 4, ‘0’); // “0000”

25. Logging
public class C {
private Log log = LogFactory.getLog(C.class);
...
if (log.isDebugEnabled()) {
log.debug(quot;log messagequot;);
}

26. CLI
Options options = new Options();
options.addOption(quot;hquot;, false, quot;display usagequot;);
CommandLine line = parser.parse(options, args);
if(line.hasOption(quot;hquot;)) {
HelpFormatter f = new HelpFormatter();
f.printHelp(quot;myprogramquot;, options);
...

27. Email
SimpleEmail email = new SimpleEmail();
email.setHostName(quot;mail.myserver.comquot;);
email.addTo(quot;jdoe@somewhere.orgquot;, quot;John Doequot;);
email.setFrom(quot;me@apache.orgquot;, quot;Mequot;);
email.setSubject(quot;Test messagequot;);
email.setMsg(quot;A simple test of commons-emailquot;);
email.send();

28. Net
NNTPClient client = new NNTPClient();
client.connect(quot;news.server.netquot;);
NewsgroupInfo[] = client.listNewsgroups();
client.disconnect();

29. JXPath
XPathContext context =
JXPathContext.newContext(dom);
String value = (String)
context.getValue(quot;/my/xpath/to/valuequot;);

30. VFS
FileSystemManager fs = VFS.getManager();
FileObject jar = fs.resolveFile(
quot;jar:lib/aJarFile.jarquot; );
FileObject[] childs = jar.getChildren();
for (int i=0; i < childs.length; i++ ) {
...

31. JCI
JavaCompiler compiler =
new EclipseJavaCompiler();
ResourceStore store =
new MemoryResourceStore();
CompilationResult result = compiler.compile(
new String[] { quot;org/MyClass.javaquot; },
new FileResourceReader(directory),
store );

32. Exec
OutputStream out;
OutputStream error;
CommandLine cl = new CommandLineImpl();
cl.setExecutable(quot;path/to/exequot;);
cl.addArgument(quot;argquot;);
exec.execute(cl, out, error);

33. Proxy
o = (MyObject) new CglibProxyFactory()
.createInterceptorProxy(
new MyObjectImpl(),
new LoggingInterceptor(log),
new Class[]{ MyObject.class });
o.test(”test”);
[DEBUG] - BEGIN test(test)
[DEBUG] - END test()

34. Overview
attributes, beanutils, betwixt, chain,
cli, codec, collections, configuration,
daemon, dbcp, dbutils, digester,
discovery, el, email, fileupload,
httpclient, io, jci, jelly, jexl, jxpath,
lang, launcher, logging, math,
modeler, net, pool, primitives,
proxy, scxml, transaction, validator,
vfs

35. Sandbox

36. CSV
String[][] data = CSVParser.parse(string);
CSVParser parser = new CSVParser(reader,’;’);
String[][] data = parser.getAllValues();

37. Javaflow
class MyRunnable implements Runnable {
public void run() {
for(int i=0; i<10; i++ )
Continuation.suspend();
}}
Continuation c = Continuation.startWith(
new MyRunnable());
Continuation d = Continuation.continueWith(c);
...

38. OpenPGP
keyRing = new BouncyCastleKeyRing(
secret, public, password);
signer = new BouncyCastleOpenPgpSigner();
signer.detachedSign(
fileInputStream
signatureOutputStream,
keyId,
keyRing,
true );

39. Overview
compress, csv, expression,
finder, flatfile, functor, i18n,
id, javaflow, jnet, js2j, me,
monitoring, nabla, openpgp,
performance, pipeline,
validator2

40. Dormant

41. Overview
benchmark, cache, clazz, codec-
mulipart, combo, contract, events,
feedparser, filters, functor, grant,
graph2, http, jex, jjar, jpath, jrcs, jux,
latka, mapper, messenger, pattern,
periodicity, reflect, resources, rupert,
scaffold, services, servlet,
simplestore, tbm, test, threading,
threadpool, workflow, xmlio, xmlunit,
xo

42. direct dependency
no dependency
20%
80%

43. We need you!
dev@commons.apache.org

44. Thanks!
http://vafer.org/blog
http://twitter.com/tcurdt