Develop Reference

ANT to Maven Migration. Maven alternative to build.xml

Background:
I am working on a open source tool called draw.io which is based on ANT build system and uses Java servelets to handle request. I am supposed to migrate it to spring boot with using same front end files. I put those files in static folder and tried to build the project. I figured that the front end js files were not getting build (i.e. were not getting converted to app.min.js, which is the main entry point for front end files), in the process and none of the js changes were getting reflected in the file.
I figured that this process was mentioned in build.xml as part of various steps which is ANT specific configuration. Now, I have to achieve the same in maven as the migration process.
How do we convert build.xml to maven or what is the maven alternative of achieving the tasks mentioned in the build.xml as part of build process?
This is the high level view of build.xml:->
I am also providing the link of build.xml here...
Please provide me with some direction.

Before migrating to maven, I hope you understand why you are moving to maven from ant.
You should try for finding alternative plugins for the relevant ant task. The below plugin might do what you are trying to achieve in ant
<plugin>
<groupId>com.github.blutorange</groupId>
<artifactId>closure-compiler-maven-plugin</artifactId>
<version>2.16.0</version>
<configuration>
<!-- Base configuration for all executions (bundles) -->
<baseSourceDir>${project.basedir}/src/main/resources</baseSourceDir>
<baseTargetDir>${project.build.directory}/generated-resources</baseTargetDir>
</configuration>
<executions>
<!-- Process all files in the "includes" directory individually-->
<execution>
<id>default-minify</id>
<configuration>
<encoding>UTF-8</encoding>
<sourceDir>includes</sourceDir>
<targetDir>includes</targetDir>
<includes>**/*.js</includes>
<skipMerge>true</skipMerge>
<closureLanguageOut>ECMASCRIPT5</closureLanguageOut>
</configuration>
<goals>
<goal>minify</goal>
</goals>
<phase>generate-resources</phase>
</execution>
</executions>
</plugin>
More details about the plugin : closure-compiler-maven-plugin
There are few cases during my ant to maven migration, I came across some custom tasks which I was not able to find appropriate plugins.
I used maven-antrun-plugin which keeps existing ant tasks in maven.
<plugin>
<groupId>org.apache.maven.plugins</groupId>
<artifactId>maven-antrun-plugin</artifactId>
<version>1.8</version>
<executions>
...
</executions>
</plugin>
More details about how to use the maven antrun plugin : See this
tutorial

For Maven, you need a pom.xml. There you need to define and configure the plugins you need. If you have a specific procedure written in Ant that you want to reuse, you can call it with the Maven Antrun Plugin.
Generally, Maven is very different from Ant. You don't write procedural code, but configure plugins running in a lifecycle.

Is there a maven jigsaw jlink plugin?

Does maven have a plugin for the new Java 9 jlink I have searched online but have not been able to find anything official from the maven team.

Yes. There has been some progress made to create one on Github/maven-plugins for the same.
<plugin>
<groupId>org.apache.maven.plugins</groupId>
<artifactId>maven-jlink-plugin</artifactId>
<version>3.0.0-SNAPSHOT</version>
</plugin>
The plugin in its code reads to be adaptive to JEP-282 and JEP-220 from the proposals.
And though this might look like a link too many answer. There is a working example from #khmarbaise on Github as well for this, which requires a toolchain with -
<configuration>
<jdkHome>/Library/Java/JavaVirtualMachines/jdk1.9.0_ea+170.jdk/Contents/Home</jdkHome>
</configuration>
Plus a side note from the author quoting -
Currently not more than a Proof of Concept. Everything here is speculative!
Edit1:- As shared in the comments, additional details could be found # How to create a Java runtime with Maven.
Edit2:- Dated 10 November, 2018 one can upgrade to using maven-jlink-plugin:3.0.0-alpha-1 and still provide some valuable feedback.

I'm working on ModiTect, general tooling around Java 9 modules. One of the goals of the ModiTect Maven plug-in lets you create module runtime images via jlink:
<plugin>
<groupId>org.moditect</groupId>
<artifactId>moditect-maven-plugin</artifactId>
<version>1.0.0-SNAPSHOT</version>
<executions>
<execution>
<id>create-runtime-image</id>
<phase>package</phase>
<goals>
<goal>create-runtime-image</goal>
</goals>
<configuration>
<modulePath>
<path>${project.build.directory}/modules</path>
</modulePath>
<modules>
<module>com.example.module1</module>
<module>com.example.module2</module>
</modules>
<launcher>
<name>helloWorld</name>
<module>com.example.module1</module>
</launcher>
<outputDirectory>
${project.build.directory}/jlink-image
</outputDirectory>
</configuration>
</execution>
</executions>
</plugin>
The plug-in is under active development right now and must be built from source for the time being (will deploy a first version to Maven Central soon).

there is mvn-jlink plugin which allows to call jdeps and jlink (and any tool provided by jdk), also it can download and unpack needed openjdk version from ADOPT and LIBERICA, such way allows build cross-platform images
<plugin>
<groupId>com.igormaznitsa</groupId>
<artifactId>mvn-jlink-wrapper</artifactId>
<version>1.0.0</version>
<executions>
<execution>
<id>call-jlink</id>
<goals>
<goal>jlink</goal>
</goals>
<configuration>
<jdepsReportPath>${project.build.directory}${file.separator}jdeps.out</jdepsReportPath>
<output>${project.build.directory}${file.separator}preparedJDK</output>
<addModules>
<module>java.compiler</module>
</addModules>
<options>
<option>--compress=2</option>
<option>--no-header-files</option>
<option>--no-man-pages</option>
</options>
</configuration>
</execution>
</executions>
</plugin>

Maybe check out https://github.com/ghackenberg/jigsaw-maven-plugin. The plugin also supports
jdeps --generate-module-info + javac + jar for patching unnamed modules,
jlink for creating runtime images, and
jpackage for creating application installers (only available since JDK 14 though).
You find the plugin documentation on the Github README page.
<plugin>
<groupId>io.github.ghackenberg</groupId>
<artifactId>jigsaw-maven-plugin</artifactId>
<version>1.1.3</version>
</plugin>

Issue setting the class path in Maven exec plugin when running a Main Class

I have embedded Jetty in my application. In order to automatically execute my integration tests on my build server I'd like Maven to start my application in the pre-integration-test phase. The integration tests are in another project than the application te be tested, because the tests are of a quite complex nature and should be seperated from production code.
I have tried to set up my application using the Maven exec plugin, but keep running into ClassNotFoundErrors. I use the maven-dependency-plugin to copy all dependencies to target/lib/. Until now, I haven't been able to figure out how to tell the exec plugin to add that lib folder to the class path.
This is my current exec plugin configuration:
<plugin>
<groupId>org.codehaus.mojo</groupId>
<artifactId>exec-maven-plugin</artifactId>
<version>1.2.1</version>
<executions>
<execution>
<id>default-cli</id>
<phase>pre-integration-test</phase>
<goals>
<goal>java</goal>
</goals>
<configuration>
<mainClass>com.zertificon.managementCenter.adminUi.server.WebApp</mainClass>
<!-- this does not work: -->
<classpath>${project.build.directory}/${libFolder}/</classpath>
</configuration>
</execution>
</executions>
</plugin>
The WebApp class I am trying to run originates from another Project and is installed in the local repository. I would highly apreciate any help.

Found the error: I have been using Jetty together with a Selenium Library that itself bundles Jetty, too. This lead to a wrong Jetty Version being loaded wich gave me class not found errors. Go figure.

maven properties-maven-plugin doesn't work when deploying artifact to Nexus

I am using properties-maven-plugin to read a external property file under root dir to maintain the version of parent module since there are quite a number of sub-modules in my project and the dependency tree is kinda deep.
It works fine when I build locally and install the artifacts into local repo but got the 401 error when I try to use "mvn clean deploy" to publish them to Nexus. I am pretty sure this is caused by the ineligible artifact name(releaseurl/{external.version}), external.version is supposed to be the property read from the external file. However, it ended up not being read and it just worked fine when I explicitly declare the version in the project.parent.version tag. Any thoughts or workaround? or even how you handle the version control when trying to use same version for parent and child in all the modules when dealing with a multi-module porject.
The maven pom for the plugin is as below, I saw some comments online regarding the phase, not sure if it will work if change initialize to something else:
<plugin>
<groupId>org.codehaus.mojo</groupId>
<artifactId>properties-maven-plugin</artifactId>
<executions>
<execution>
<phase>initialize</phase>
<goals>
<goal>read-project-properties</goal>
</goals>
<configuration>
<files>
<file>external-file.properties</file>
</files>
</configuration>
</execution>
</executions>
</plugin>

Get sources of a snapshot dependency on Eclipse

Something bother me a lot...
On a big project with many dependencies, some of them are set as SNAPSHOT in Maven2.
The matter is that it seems i can't get the sources through Eclipse without loading the project or fixing the dependency to the last release.
For debugging, it's really annoying me...
EDIT
This is what i get in eclipse maven console:
26/08/10 11:31:46 CEST: Downloading http://repo-maven/archiva/repository/snapshots/com/blabla/1.1-SNAPSHOT/blabla-1.1-20100824.213711-80-javadoc.jar
26/08/10 11:31:47 CEST: Could not download sources for com.blabla:blabla:1.1-20100824.213711-80
On archiva i can see the deployed stuff i want to retrieve in eclipse...
Repository snapshots
Group ID com.blabla
Artifact ID blabla
Version 1.1-20100824.213711-80
Packaging jar
Parent com.blabla bla 1.1-SNAPSHOT (View)
Other Versions 1.1-20100824.213535-79
I can download sources of this artifact with my browser but not within Eclipse... Any idea?

The matter is that it seems I can't get the sources through Eclipse without loading the project or fixing the dependency to the last release. For debugging, it's really annoying me...
Well, these modules are probably not publishing source JARs as part of the "regular" build process (i.e. outside the release). If these modules are under your control (which is my understanding), configuring the Maven Source Plugin to produce source JARs for them and deploying them in your corporate repo should solve the problem. From the Usage page:
Installing the sources along with your artifact
There are two ways to do this. You can
either bind this plugin to a phase or
you can add it to a profile. The goals
source:jar-no-fork and
source:test-jar-no-fork are preferred
for binding the goal to the build
lifecycle.
Installing the sources using a phase binding
Here is how you would configure the
plugin in your pom.xml to run
automatically during the verify phase:
<project>
...
<build>
<plugins>
<plugin>
<groupId>org.apache.maven.plugins</groupId>
<artifactId>maven-source-plugin</artifactId>
<version>2.1.2</version>
<executions>
<execution>
<id>attach-sources</id>
<phase>verify</phase>
<goals>
<goal>jar-no-fork</goal>
</goals>
</execution>
</executions>
</plugin>
</plugins>
</build>
...
</project>
We are using the verify phase here
because it is the phase that comes
before the install phase, thus making
sure that the sources jar has been
created before the install takes
place.
Installing the sources using a profile
If you want to install a jar of your
sources along with your artifact
during the release process, you can
add this to your pom.xml file:
<project>
...
<profiles>
<profile>
<id>release</id>
<build>
<plugins>
<plugin>
<groupId>org.apache.maven.plugins</groupId>
<artifactId>maven-source-plugin</artifactId>
<version>2.1.2</version>
<executions>
<execution>
<id>attach-sources</id>
<goals>
<goal>jar-no-fork</goal>
</goals>
</execution>
</executions>
</plugin>
</plugins>
</build>
</profile>
</profiles>
...
</project>
Using a profile would probably be a good idea so that building source JARs will only be done by the build running at the CI server level but not on developer machines.