First, let's review some Maven basics. Maven uses the notion of a build life-cycle to which plugins can attach. Plugins are similar to Ant tasks. When a Maven build is invoked, we specify a point in the life-cycle up to which the build should proceed. The compile phase comes before test, and test comes before package, and package comes before install. Once we have Maven setup, we can invoke the Struts build, and specify which phase the build should use.
Installing
The install phase builds up the project ("package"), and installs any JARs it needs into your local repository (e.g. ~/.m2/repository). Once installed, the JARs can be used by any other Maven project you build. The install phase is the default phase if none is specified.
To run a basic install, change to the root of the source distribution, and enter
That's it! Maven will download any dependencies the build needs; run all unit tests; package up the JARs; then install the new JARs locally. For your convenience, copies of the JARs can be found in the target directories of each module. For example, after the build, the main JAR can found at core/target/struts2-core-2.0-SNAPSHOT.jar.
Other phases
There are other phases that can be useful when working with Maven. The package phase will just JAR (or WAR) the modules. The test phase will only execute unit-tests. The compile phase will only build the source-code (but not the test sources). And the clean phase will remove all artifacts, typically the entire target directory.
Building IDE project files
Maven has a great feature that will allow you to build up your IDEA or Eclipse project files based on the project build structure. Using the Maven project files helps keep developers in-sync and efficient. The IDEA project files are pre-configured to define in the Run/Debug menu many common tasks, such as "execute all tests", "launch the showcase sample app", and so fort.
IDEA by JetBrains
The Maven IDEA plugin creates IDEA project and modules files, based on the Maven build configuraton (pom.xml).
First, be sure you have the latest IDEA plugin for Maven.
Most often, we use Maven to build projects, but it can also run plugins directly. To build an IDEA project file for Struts 2, including all the modules, run
Maven will generate struts-parent.ipr, struts-parent.iws, and an iml file for each module listed Open up struts-parent.ipr in IDEA, and you should be good to go.
If you ever need to rebuild your projects, running the idea:idea command again will update your files without overriding any information that doesn't conflict. If you do want to overwrite the project files, specify the overwrite parameter as true.
Eclipse
For Eclipse, try
IMPORTANT: Running the Sample Applications from Eclipse or non-IDEA IDEs
Currently the sample applications can be deployed using the Maven 2 Jetty plugin. For example, you can run the showcase example application from the command line:
You could also use one of the Maven IDE plugins to run the plugin or simply execute the mvn or mvn.bat file as an external application within your IDE.
A good tutorial on how to use the Maven 2 jetty plugin along with your IDE, including JPDA debugging support, can be found at the Apache Wicket documentation.
Maven Tips
A few helpful tips for using Maven are provided:
Skip exporting pages from Confluence
The whole Struts2 documentation resists on Confluence and during normal build process is exported with SiteExporter tool locally to html files. To perform that, you must have an account on Confluence. In most cases you don't need to export the whole Confluence, so you can skip this, just type command:
Skip creating assemblies
During normal development cycle you don't need to create assembly packages which consist of all the libraries, example apps and docs - you can skip them as well:
Offline mode
If you are disconnected from the Internet or simply wish to make your build faster, pass in the -o argument and Maven won't check for new modules to download.
OutOfMemoryError
If you get an OutOfMemoryError while running the tests:
Skipping test execution
Although this shouldn't ever happen, sometimes tests do fail and you need to build the framework anyway. If there's a problem, you can pass in the skip tests parameter.
Of course, if you find tests are failing, please submit a patch to fix them!
Debugging build failures
Struts 2 depends on the current snapshot artifact of XWork 2. Unfortunately, if XWork 2 is modified in a significant way, the Struts build doesn't check for and retrieve a new version of the XWork snapshot jar, resulting in compilation or unit test failures.
The solution is to clear out any stale XWork 2 jars in your local Maven repository, usually by removing the directory ~/.m2/repository/opensymphony. This will force the Struts Maven build to pull down a fresh copy of XWork and hopefully resolve your problem.
Mirrors
The default mirror for Maven builds ("ibiblio") can be slow and unreliable. Maven lets you specify alternative mirrors so that you don't have to depend on ibiblio for everything.
You can add new mirrors through the Settings file (~/.m2/settings.xml).
First time building
In some cases it has been seen that Maven will complain if a module doesn't exist, even though it is part of the current build. Often, the missing module turns up when executing mvn package. A simple fix for this is to run mvn install instead. If you have to do this, it will probably only be a one time thing.