In this article I will discuss the creation of a Maven Archetype that my students or anyone else can use to begin developing a JavaFX application. Like so many adventures in programming this process began quickly and then bogged down in dealing with specific details. If you want to create your own archetype then this article will be helpful. Don’t forget to read the Sip of Whine section at the end.
The source code for the sample JavaFX project is at https://github.com/omnijava/SimpleJavaFX
The archetype folder ready for installation on your system is in the release of https://github.com/omnijava/ArchetypeJavaFX/releases
Step 1: Write a program
Archetypes can be created using either a bottom up or top down approach. By far the easiest approach is top down. You begin by writing a very simple Maven managed JavaFX application. You are providing a skeleton of an application that contains required or recommended packages, resources and source code.
The application I created is a simple JavaFX Stage with one Scene with a button that when pressed display some text. The code that delivers this experience is in the format that I want my students to follow. A few years ago some students created a hash tag to poke fun at my stringent rules, #KFCStandard. That I how I describe any rules or instructions that I provide to students that must be followed. This project exemplifies a number of #KFCStandards in the areas of pom files, how to start a JavaFX application, how to do unit testing and how to comment code. If you are not one of my students then you may have issues with my archetype. I would really like to hear your thoughts. Living in academia I worry that I loose site of the real world of software development.
Do your best to ensure that the program works. If you are creating an archetype where the files are empty waiting for the user to fill them in then this is likely not going to be a problem. If your code does something, as mine does, spend some time with it to get it right.
Archetype Tip #1: Always create packages that begin with the maven groupId and optionally the artifactId. This allows the user of your archetype to use their own package names.
Archetype Tip #2: If you reference the mainClass in the pom.xml as:
<mainClass>com.kfcstandard.javafxarchetype.MainAppFX</mainClass>
Change it to
<mainClass>${groupId}.${artifactId}.MainAppFX</mainClass>
Archetype Tip #3: If you need to have a package created when the archetype is used but you don’t have anything to place in the package then add an empty file. Maven will not create packages if there are no files in it.
pom.xml note: When I compile with NetBeans I get two warnings regarding the pom.xml. One tells me that ${groupId} is deprecated in favour of ${project.groupId} and the second tells me that ${artifactId} is deprecated in favour of ${project.artifactId}. The NetBeans 8.01 editor only recognizes ${project.groupId} and not the other. Therefore for now I am using the deprecated versions.
Step 2: Install Maven
I use NetBeans, my personal preference for an IDE and what I used in developing the archetype code. In one course that I teach I must use Eclipse. Both of these IDEs and others now provide good support for Maven. People who know me will now roll their eyes as I say that creating an archetype is easier to do at the command line. Download and install Maven from https://maven.apache.org/download.cgi. Read the install notes at https://maven.apache.org/install.html. You need to have Maven’s bin folder in the executable path and Windows users must have a JAVA_HOME environment variable.
Maven note: Some IDEs, such as NetBeans, contain the maven command line program. I recommend downloading Maven so that you are working with the most recent version.
Step 3: Clean up the project
Locate the folder your project is in. Delete everything in the project’s folder except for the src folder and the pom.xml file. You may want to make a copy of the project folder because you will be changing one file that will cause an exception to thrown if you run the project after the change.
Step 4: Alter the fxml file
If you are creating a project with an fxml file in the resources folder it likely contains a reference to its java controller file. In this project the file Scene.fxml contains:
fx:controller=”com.kenfogel.archetypejavafx.controllers.FXMLController”>
You need to replace the part of the package that matches the groupId and artifactId with the matching properties. The change looks like:
fx:controller=”${groupId}.${artifactId}.controllers.FXMLController”>
Step 5: Archetype Resolution or Generating the Archetype
Archetype Resolution is the term that the Maven developers use to describe using Maven to generate the archetype. This task will create a new target folder that contains the archetype version of your code.
Open a command window in the project’s root folder. In my case that is D:\mvnbuild\ArchetypeJavaFX. At the prompt issue the command:
mvn archetype:create-from-project
You may ignore all the warnings.
If all has gone well you will you will have the following folder that is not normally part of a Maven build:
D:\NetBeansProjects\javafxarchetype\target\generated-sources\archetype
Step 6: Make the fxml files filterable
The project in the archetype folder now contains two files named archetype-metadata.xml. This xml file determines which files will go into the archetype and whether or not they get filtered. To filter is to substitute a property with a value. That is why we changed the Scene.fxml file in the previous step. The archetype-metadata.xml files do not show that files in the fxml folder of resources are filterable. Locate these two files, mine are in:
D:\NetBeansProjects\javafxarchetype\target\generated-sources\archetype\src\main\resources\META-INF\maven
And
D:\NetBeansProjects\javafxarchetype\target\generated-sources\archetype\target\classes\META-INF\maven
Edit the files, they are identical, to change:
<fileSet encoding="UTF-8"> <directory>src/main/resources</directory> <includes> <include>**/*.fxml</include> <include>**/*.css</include> </includes> </fileSet>
to read
<fileSet filtered="true" encoding="UTF-8"> <directory>src/main/resources</directory> <includes> <include>**/*.fxml</include> <include>**/*.css</include> </includes> </fileSet>
Step 7: Install the Archetype in your repository
Open a command window in your archetype folder and at the prompt enter the following commnd:
D:\NetBeansProjects\javafxarchetype\target\generated-sources\archetype>mvn install
Ignore any warnings. The archetype should be safely in
.m2\repository\com\kfcstandard\javafxarchetype-archetype
where ever your .m2 folder is.
Step 8a: Test if it works with the Maven command line
Create a new folder on your computer for the test. I created D:\mvntest. Open a command window in this folder. Run the command:
D:\mvntest>mvn archetype:generate -DarchetypeCatalog=local
What follows next is pretty straight forward. Here is my output. Notice that you need to enter the groupId, artifactId, version and package. The package should be made up from the groupId and artifactId.
[INFO] Scanning for projects... [INFO] [INFO] ------------------------------------------------------------------------ [INFO] Building Maven Stub Project (No POM) 1 [INFO] ------------------------------------------------------------------------ [INFO] [INFO] >>> maven-archetype-plugin:2.4:generate (default-cli) > generate-sources @ standalone-pom >>> [INFO] [INFO] <<< maven-archetype-plugin:2.4:generate (default-cli) < generate-sources @ standalone-pom <<< [INFO] [INFO] --- maven-archetype-plugin:2.4:generate (default-cli) @ standalone-pom --- [INFO] Generating project in Interactive mode [INFO] No archetype defined. Using maven-archetype-quickstart (org.apache.maven.archetypes:maven-archetype-quickstart:1.0) Choose archetype: 1: local -> com.kfcstandard:javafxarchetype-archetype (Standard starting point for JavaFX programs for students of Ken Fogel) Choose a number or apply filter (format: [groupId:]artifactId, case sensitive contains): : 1 Define value for property 'groupId': : com.squirrel Define value for property 'artifactId': : moose Define value for property 'version': 1.0-SNAPSHOT: : Define value for property 'package': com.squirrel: : com.squirrel.moose Confirm properties configuration: groupId: com.squirrel artifactId: moose version: 1.0-SNAPSHOT package: com.squirrel.moose Y: : y [INFO] ---------------------------------------------------------------------------- [INFO] Using following parameters for creating project from Archetype: javafxarchetype-archetype:0.1 [INFO] ---------------------------------------------------------------------------- [INFO] Parameter: groupId, Value: com.squirrel [INFO] Parameter: artifactId, Value: moose [INFO] Parameter: version, Value: 1.0-SNAPSHOT [INFO] Parameter: package, Value: com.squirrel.moose [INFO] Parameter: packageInPathFormat, Value: com/squirrel/moose [INFO] Parameter: package, Value: com.squirrel.moose [INFO] Parameter: version, Value: 1.0-SNAPSHOT [INFO] Parameter: groupId, Value: com.squirrel [INFO] Parameter: artifactId, Value: moose [INFO] project created from Archetype in dir: D:\mvntest\moose [INFO] ------------------------------------------------------------------------ [INFO] BUILD SUCCESS [INFO] ------------------------------------------------------------------------ [INFO] Total time: 30.660 s [INFO] Finished at: 2015-09-01T20:48:04-04:00 [INFO] Final Memory: 13M/243M [INFO] ------------------------------------------------------------------------
D:\mvntest>
In the project that has been created in the mvnbuild folder examine the Scene.fxml file and ensure that it has the path to the controller based on the groupId and artifactId you entered. Check out the pom.xml in the project and verify that the mainClass has the proper package.
Step 8b: Testing with NetBeans
Start NetBeans and select:
File -> New Project
In the dialog choose Maven on the left and Project from Archetype on the right and click on Next.
Scroll down to find javafxarchetype-archetype, select it and click on Next.
On the next screen you can fill in the Project Name that becomes the Artifact Id, the Group Id, and Version. It’s unusual to change the Package which defaults to Group Id plus Artifact Id.
Click on Finish and you will a have a project loaded. You should be able to Clean and Build and then Run this project.
You are now ready to add your code to the project.
Step 8c: Testing with Eclipse
Start Eclipse and then choose File -> New -> Other. Open Maven in this dialog and select Maven Project.
There is nothing to change in the next dialog so just click on Next.
In the next dialog you should see all the archetypes available to Eclipse. On my system the local archetypes appear first so the archetype we created should be first. Select it and click on Next.
Now you can fill in the Group Id, Artifact Id, Version and Package. Like NetBeans the Package is made up of the Group Id and Artifact Id. Click on Finish.
The project will appear in the Package Explorer. Right mouse click on the project and choose Run As -> Maven Build and at the dialog just choose Run. The program should open. Close it and you are now ready to add your code to the project.
A Sip of Whine
In learning how to create a maven archetype I was confronted with a serious issue in regards to what I found on the web. Almost every blog, post or stackoverflow answer was nothing more than paraphrasing the Apache Maven documentation. It looks to me these authors have never used Maven or Archetypes in real world situations. The same holds true for the Apache Maven documentation. It lacks any real world examples and is far from being written in plain language.
There is also a bug in the Maven Archetype system. It took me two days to track it down. If you have a package made up of the groupId and artifactId in the src/main/java folder and you have the exact same package in src/test/java then the archetype will be damaged and will not work. The solution was to place the tests in a folder one level below the package. I will report it.
