Our Blog. We have some things we'd like to share.

Threading in java is fairly easy and now with java 1.5 some of the stuff that was harder has become even easier. A few years ago someone pointed me to a site that had some concurrency utils that where the precursor to what are now the concurrent utils in java 1.5. They are very close in functionality and if you can’t use java 1.5 the older version of the utils will work with older versions of java and give you a lot of the same functionality.

I’m going to give a quick thread pooling example using both the new and old concurrency utils. I picked the thread pooling out of both since that seems to be what I end up using the most out of all the new utilities. I may revisit this again at some point to go over the periodic executors or some of the other things I have used but just not as much.

(more…)

While developing a webservice based application we ran across some issues using a self signed certificate. After running our wsdl2java ant task we got the following error using Java 1.4:

sun.security.validator.ValidatorException: No trusted certificate found

Using Java 1.5 the error looks like this:

sun.security.validator.ValidatorException: PKIX path building failed:
sun.security.provider.certpath.SunCertPathBuilderException:
unable to find valid certification path to requested targ

Fair enough. Java is telling us we need to import our self signed certificate into java:

/usr/local/java5/bin/keytool -import -alias mycert \\
  -file server.crt -keystore /usr/local/java5/jre/lib/security/cacerts
Enter keystore password:  changeit
... CERTIFICATE DUMP ...
Trust this certificate? [no]:  yes
Certificate was added to keystore

Running our ant task again:

java.io.IOException: HTTPS hostname wrong:  should be <localhost>
  at sun.net.www.protocol.https.HttpsClient.checkURLSpoofing(HttpsClient.java:490)
  at sun.net.www.protocol.https.HttpsClient.afterConnect(HttpsClient.java:415)
...LONG STACK TRACE TRUNCATED....
</localhost>

(more…)

I recently ran into an issue where doing a large number of inserts and updates in an Oracle 8i database was taking forever. I was already using a prepared statement and commiting only after a certain number of rows. After some digging I found out that there is a special Oracle way of doing batch updates that made things a good bit faster. They do support the normal addBatch batch updates but it isn’t as fast as using their special way.

Here is an example of how to do things their way:

public static void doBatchInsert(List aLargeList, Connection connection) throws SQLException
{
  // You have to turn auto commit off, if you are doing a large set of inserts and updates you are probably doing this already.
  connection.setAutoCommit(false);

  PreparedStatement preparedStatement = connection.prepareStatement("insert into a_table(a_col) values (?)");
  // This is the magic. Set the number of statements to allow in one batch
  ((OraclePreparedStatement)ps).setExecuteBatch (10);

  int count = 0;
  for(Iterator i=aLargeList.iterator(); i.hasNext(); count++)
  {
    YourData yourData = (YourData)i.next();

    preparedStatement.setInt(1, yourData.getAnInt());
    preparedStatement.executeUpdate();

    if(count % 10 == 0)
    {
      // Send all currently queued statements
      ((OraclePreparedStatement)preparedStatement).sendBatch();
      connection.commit();
    }
  }

  ((OraclePreparedStatement)preparedStatement).sendBatch();
  connection.commit();
  preapredStatement.close();
}

For more information see the following link:
http://www.oracle.com/technology/products/oracle9i/daily/jun07.html

I realized today just how much I used the Commons Collections library. Sure, there’s alot of anonymous inner classes, but after years of writing Swing I’ve gotten used to sort of crossing my eyes and looking past the syntactic cruft.

Here’s a silly example. Let’s map the names in the Greek alphabet to actual letters. Here’s our data

    Map nameToLetter = new HashMap();
    nameToLetter.put("ALPHA","a");
    nameToLetter.put("BETA","b");
    nameToLetter.put("GAMMA","g");
    nameToLetter.put("DELTA","d");

    String[] values = {"ALPHA","BETA","GAMMA","GAMMA","DELTA","EPSILON"};
    List valueList = Arrays.asList(values);

Let’s convert that valueList to the letters:

    Collection resultCollection = CollectionUtils.collect
    (
      valueList,
      TransformerUtils.mapTransformer(nameToLetter)
    );

    System.out.println(resultCollection);

>[a, b, g, g, d, null]

Hmm…how do we go back the other way….
(more…)