10.5 Summary

This chapter examined ways Groovy helps with testing and building web applications. Unit tests are similar to their Java counterparts, but the Gradle build framework provides a great way to do integration testing of deployed applications.

The Groovy JDK includes classes like ServletCategory, which simplify the implementation of web components. Groovy also has a built-in web scripting engine called groovlets, which makes it easy to work with requests, responses, sessions, and input parameters in a web application.

Finally, this chapter includes a brief discussion of Grails, possibly the biggest Java/ Groovy integration success story of them all.

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appendix A Installing Groovy

Installing Groovy is easy. This appendix shows you how to do it, with a review of the various options involved.

A.1 Installing a JDK

Groovy generates Java bytecodes that are interpreted by a Java virtual machine. This means you have to have Java installed in order to install Groovy. You need a full Java Development Kit (JDK), rather than a Java Runtime Environment (JRE). You only need the Standard Edition (SE) of Java, rather than the Enterprise1 Edition.

The official JDK for Java SE is available from Oracle at http://mng.bz/83Ct. At the time of this writing, the current version is Java SE 7u25 (Java 7, update 25), but Groovy works on any version of Java 1.5 and above.

Be sure to set an environment variable called JAVA_HOME to point to the installation directory. You also probably want to add the bin folder under JAVA_HOME to your path.

On Windows that will look like this:

C:\> set JAVA_HOME="C:\Program Files\Java\jdk1.7.0"

C:\> set PATH=%JAVA_HOME%\bin;%PATH%

Those commands will set the JAVA_HOME and PATH properties in the local shell. To set them everywhere, right-click My Computer, select Properties, click Advanced, and then click Environment Variables. Add them as System variables, and start a new shell.2

1Just as an aside, when did the word business get deprecated in favor of the word enterprise? Is it a Star Trek thing? Does being an Enterprise Architect mean you design starships for a living? Are Enterprise Java Beans used when making coffee on a starship?

2The specifics of the process will be slightly different on different Windows versions, but the concepts are the same. Set the variables as System environment variables, and start a new shell because Windows won’t update an existing one.

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On Macs or Unix flavors, the same settings are

$ export JAVA_HOME=/Library/Java/… $ export PATH=$PATH:$JAVA_HOME/bin

There are too many variations on these statements to count, depending on directory structure and version numbers, but the principles are always the same: install Java, set the JAVA_HOME variable to point to it, and add its bin subdirectory to your path.

A.2 Installing Groovy

Assuming you’ve installed Java, installing Groovy is easy. Again, there are several options, but the basic process comes down to downloading and unzipping the distribution, setting a GROOVY_HOME environment variable, and adding its bin subdirectory to your path.

If you’re not a fan of automated installers or you don’t have root privileges on your machine, you can download a zipped, binary distribution of Groovy directly. The current version can always be found at http://groovy.codehaus.org/Download. You can get either the binary release or the source release (or both). Either way, unzip the download into a directory of your choice.

On Windows, following the same pattern as the Java installation, it’s

C:\> set GROOVY_HOME=C:\Groovy\groovy-2.1.6

C:\> set PATH=%GROOVY_HOME%\bin;%PATH%

On a Mac or Unix, the same process is

$ export GROOVY_HOME=...

$ export PATH=$PATH:$GROOVY_HOME/bin

If you don’t mind installers, a good one is available for Windows. An EXE installer is available on the same download page, which will install Groovy to a directory of your choice, set the GROOVY_HOME variable for you, and add the bin folder underneath it to your path. It also offers to install some optional libraries for you, which are useful and do not interfere with your regular installation in any way. I’ve been using the Windows installer at client sites for years and have never had a problem with it. It will, by the way, notify you if you don’t have a JAVA_HOME environment variable set.

If you’re on a Mac or other Unix box, you have other convenient alternatives available. First, there’s a MacPorts (www.macports.org) option. Run

$ sudo port install groovy

That will download and install the latest version. If you prefer HomeBrew (http:// mxcl.github.io/homebrew), the relevant command is

$ brew install groovy

That, too, will download the latest version, install it, and create soft links to the executable scripts in your path.

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The other major alternative is to use GVM, the Groovy enVironment Manager (http://gvmtool.net). This is the best option if you plan to switch versions at any time. GVM is installed using curl, with this command:

$ curl –s get.gvmtool.net | bash

GVM assumes you are using a bash shell, but the same process works for most Unix flavors. It also works on Windows if you install Cygwin. See the web page for details.

The great advantage of GVM is that it makes switching versions almost trivially easy. If you have GVM installed, you can find out which versions of Groovy are available by typing

$ gvm list groovy

You can install the latest one like this:

$ gvm install groovy

If you supply a version number to the install command, you can select which version of Groovy to install. You can switch from one version of Groovy to another using

$ gvm use groovy [version]

If the version you request isn’t installed, GVM will download and install it for you. In my own work, I don’t switch Groovy versions that often, but I switch Grails versions frequently and the same tool works for Groovy, Grails, Griffon, and a few other software distributions. GVM installs software under a .gvm folder in your home directory, so you should set the GROOVY_HOME variable to point there. For example, on my Mac, I have

$ export GROOVY_HOME=/Users/kousen/.gvm/groovy/current

That’s useful because switching versions through GVM updates the current link. I don’t have to explicitly add that folder to my path, though, because the tool adds soft links to a bin folder already in my path.

A.3 Testing your installation

The easiest way to see if your Groovy installation is working is to try out the Groovy shell or the Groovy console. If you type

$ groovysh

you should get a response like this:

Groovy Shell (2.1.5, JVM: 1.7.0_11) Type 'help' or '\h' for help.

------------------------------------

groovy:000> println 'Hello, World!' Hello, World!

===> null groovy:000>

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