Introducing JugList.net

As part of a homeschool project and a way to try out their budding Groovy & Grails development skills, two of my sons, Zak and Ben, have been working on a website. Their creation is now up and running and you can see it at www.juglist.net

JugList.Net is a searchable directory of Java User Groups around the world.


You can search for a JUG (Java User Group) by name, city, state/province or country. If you still can't find a JUG in your area, there is a link to an article, by yours truly, that gives some tips on starting your own group.

Java User Groups are a valuable resource for honing your craft and building your career. They also provide a great way for experienced programmers to give a little back to the community. If you are not involved in a JUG yet, then check out juglist.net and find one near you.

Another way to use Groovy in the Enterprise

Another great way to incorporate Groovy into your enterprise Java projects is Groovy SQL. GSql makes JDBC access so easy and Groovy's seamless Java integration and dynamic nature provides for some interesting ways to take advantage of it.

In this example we'll build a utility class that will use convention to turn an SQL select statement into a List of data transfer objects.

Our goal here is to take an SQL statement and a Class, execute that statement and use the results to populate instances of the Class. We will assume the convention of camel case for object properties and underscores for database fields, so that a field called LAST_NAME would be mapped to a property called lastName. We will also assume that the select statement will only return fields that have a corresponding property in the Class.

So let's see what this might look like:

static Collection getData(String query, Class clazz, Connection con){
    def field = ''
    def result = []
    def sql = new Sql(con)
    sql.rows(query).each {row ->
        def dto = clazz.newInstance()
        row.keySet().each{
            field = toCamelCase(it)
            dto."${field}" = row."${it}"
        }
        result << dto
    }
    result
}

After defining a few variables, we create our groovy.sql.Sql object using the constructor that takes a Connection. This will allow us to use Connections provided by an application server such as WebLogic or WebSphere. We could easily change this method to take advantage of the other constructors.

Next we'll call the rows method of the Sql class, which will execute the SQL statement and return an ArrayList of GroovyRowResults. Now we'll iterate through this ArrayList and create a new instance of our DTO class for each row. GroovyRowResult implements the Map interface so we can loop through its keys with row.keySet().each. This will give us each of the fields in that row and we will turn them into property names with a call to the toCamelCase() method (which we'll look at shortly). Notice how we take advantage of GStrings to dynamically access properties of our DTO as well as keys of the row map. After we assign each of the fields in the row to properties of the DTO instance we add it to the result List. When the loop is done we just return the List. Obviously, more can be done to make this more robust and more flexible, but it's pretty amazing how easy it was to build a Groovy class that can replace tons of repetitive Java code.

Let's take a look at how we could use this class from a Java project:

...
    Connection con = getConnectionFromPool();
    String query = "SELECT FIRST_NAME, LAST_NAME, EMAIL FROM MEMBER";
    Collection members = GroovyData.getData(query, MemberDTO.class, con);
...

That's all there is to it.

Now let's take a quick look at the toCamelCase() method we mentioned above. This doesn't directly have anything to do with the purpose of this post, but I am hoping that someone might see this and offer a groovier way to do the same thing. Basically the goal is to take a database field name such as LAST_NAME and turn it into a camelCase string like lastName. Here's how I did it:

static String toCamelCase(String val){
    def sb = new StringBuffer()
    Boolean newWord = false
    val.toLowerCase().each{
        if (it == '_')
            newWord = true
        else{
            if (newWord){
                newWord = false
                sb << it.toUpperCase()
            }
            else
                sb << it
        }
    }
    sb.toString()
}

I was sure there was a groovier way to do this and, sure enough, Andres Almiray came up with this awesome improvement:

static String toCamelCase(String val){
    def result = val.split("_").collect { word ->
        word[0].toUpperCase() + word[1..-1].toLowerCase()
    }.join("")
    result[0].toLowerCase() + result[1..-1]
}

Thanks Andres! And if that wasn't groovy enough, Ted Naleid came up with this cool mix of regular expressions and meta-programming. Good stuff Ted!

def camelCaseConverter(orig) {
    orig.toLowerCase().replaceAll(/_(\w)?/) { wholeMatch, firstLetter ->
        firstLetter?.toUpperCase() ?: ""
    }
}

String.metaClass.toCamelCase = {->
    camelCaseConverter(delegate)
}

Groovy and Grails at JavaOne

It's less than a week until JavaOne 2008! It is going to be an exciting week packed full of brain stretching content. There will be technical sessions, birds of a feather sessions, panels, keynotes, etc. on just about everything having anything to do with Java. But most importantly, there will be a bunch of Groovy and Grails related sessions. Starting with Jeff Brown's Grails presentation at Community One on Monday, followed by the G2One / NoFluffJustStuff gala Monday evening at the W Hotel.

Then for the rest of the week a groovy search in the Content Catalog turned up the following list:

ID	Session Title	Speaker(s)	Date / Time	Room
TS-5771	The Duke and the Elephant: PHP Meets Java™ Technology--the Best of Both Worlds	Rob Nicholson, IBM	Tuesday 05/06/2008 10:50 AM -11:50 AM	Esplanade 301
TS-5764	Grails in Depth	Guillaume Laforge, G2One, Inc., Graeme Rocher, G2One Inc	Tuesday 05/06/2008 6:00 PM -7:00 PM	Esplanade 307-310
BOF-5613	Jersey: RESTful Web Services Made Easy	Jakub Podlesak, Sun Microsystems Paul Sandoz, Sun Microsystems, Inc.	Tuesday 05/06/2008 8:30 PM -9:20 PM	Esplanade 307-310
PAN-5435	The Script Bowl: A Rapid-Fire Comparison of Scripting Languages	Guillaume Laforge, G2One, Inc., Charles Nutter, Sun Microsystems, Inc., Jorge Ortiz, Stanford, Raghavan Srinivas, Sun Microsystems, Inc., Frank Wierzbicki, Sun Microsystems	Wednesday 05/07/2008 9:30 AM -10:30 AM	Gateway 104
TS-5572	Groovy, the Red Pill: Metaprogramming--How to Blow the Mind of Developers on the Java™ Platform	Scott Davis, Davisworld Consulting, Inc.	Wednesday 05/07/2008 9:30 AM -10:30 AM	North Mtg-121/122/124/125
TS-5815	Going Mobile with JavaFX™ Script Technology, Groovy, and Google Android	Mike Mannion, Canoo Engineering AG	Wednesday 05/07/2008 10:50 AM -11:50 AM	Esplanade 301
TS-6050	Comparing JRuby and Groovy	Neal Ford, ThoughtWorks Inc.	Wednesday 05/07/2008 1:30 PM -2:30 PM	North Mtg-121/122/124/125
TS-5274	Groovy on a Cloud: Testing Java™ Platform, Enterprise Edition (Java EE Platform) Applications on Amazon EC2	Chris Richardson, Chris Richardson Consulting, Inc.	Wednesday 05/07/2008 4:10 PM -5:10 PM	Gateway 104
TS-6213	Boldly Go Where the Java™ Programming Language Has Never Gone Before	Geert Bevin, Terracotta	Wednesday 05/07/2008 4:10 PM -5:10 PM	North Mtg-121/122/124/125
BOF-5102	Cooking Your Own Groovy Builder: A Step Forward into Domain-Specific Languages	Andres Almiray, Oracle, Ixchel Ruiz, Clemente Camara y Asociados	Wednesday 05/07/2008 8:30 PM -9:20 PM	Gateway 104
BOF-5110	Extending Groovy’s Swing User Interface in Builder to Build Richer Applications	Danno Ferrin, Intelligent Software Solutions, Inc., James Williams, Spatial Networks	Wednesday 05/07/2008 8:30 PM -9:20 PM	Hall E 133
TS-5793	Groovy and Grails: Changing the Landscape of Java™ Platform, Enterprise Edition (Java EE Platform) Patterns	Guillaume Laforge, G2One, Inc., Graeme Rocher, G2One Inc	Thursday 05/08/2008 9:30 AM -10:30 AM	North Mtg-121/122/124/125
TS-5693	Writing Your Own JSR-Compliant, Domain-Specific Scripting Language	John Colosi, VeriSign, Inc.; David Smith, VeriSign Inc.	Thursday 05/08/2008 1:30 PM -2:30 PM	Esplanade 301
TS-6457	Choosing Your Java™ Technology-Based Web Framework: A Comparison	Richard Pack, Hyperic; Stacey Schneider, Hyperic	Thursday 05/08/2008 2:50 PM -3:50 PM	Esplanade 307-310
TS-6606	Patterns for Integrating Java™ and JavaScript™ Technology: Tales from the Front Lines	David Caldwell, David P. Caldwell, Inc.	Thursday 05/08/2008 2:50 PM -3:50 PM	North Mtg-121/122/124/125
BOF-5101	Boosting Your Testing Productivity with Groovy	Andres Almiray, Oracle;, James Williams, Spatial Networks	Thursday 05/08/2008 7:30 PM -8:20 PM	Gateway 102/103
TS-5098	Building Rich Applications with Groovy's SwingBuilder	Andres Almiray, Oracle;, Danno Ferrin, Intelligent Software Solutions, Inc.	Friday 05/09/2008 12:10 PM -1:10 PM	Esplanade 305
TS-6050	Comparing JRuby and Groovy	Neal Ford, ThoughtWorks Inc.	Friday 05/09/2008 1:30 PM -2:30 PM	Esplanade 303
TS-6039	Jython - Implementing Dynamic Language Features for the Java™ Platform Ecosystem	Jim Baker, Zyasoft, Tobias Ivarsson, Neo Technology	Friday 05/09/2008 2:50 PM -3:50 PM	Esplanade 305

Well, if you read this far and if you happen to be wandering around the Pavillion on Tuesday afternoon at 3:30, I will be giving a mini-talk on Java User Groups at the java.net Community Corner. (That way I can say that I gave a presentation at JavaOne).