Maven command line usage -

Maven command line usage

Figure 274. CLI example

mvn --batch-mode -e archetype:generate \
-DgroupId=de.hdm_stuttgart.mi.sd1 -DartifactId=second -Dversion=0.9 \
-DarchetypeGroupId=org.apache.maven.archetypes -DarchetypeArtifactId=maven-archetype-quickstart -DarchetypeVersion=1.4

[INFO] Scanning for projects...
      ...
[INFO] BUILD SUCCESS ...

See artifact reference.

The MI department provides modified archetypes supporting more current versions of unit testing software. These are being provided by a Maven repository server:

Figure 275. Supplementary MI Maven archetypes

MI nexus repository server

Configuration:

mkdir -p ~/.m2 ❶
nano ~/.m2/settings.xml ❷

❶

Create an empty .m2 Maven configuration and caching related directory below your home directory ~. The -p option avoids an error message in case ~/.m2 already exists.

❷

Use a text editor like nano, vim, emacs, IntelliJ,... for creating the following (presumably new) file ~/.m2/settings.xml:

<settings xmlns="http://maven.apache.org/SETTINGS/1.0.0"
  xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
  xsi:schemaLocation="http://maven.apache.org/SETTINGS/1.0.0 http://maven.apache.org/xsd/settings-1.0.0.xsd">

  <profiles>
    <profile>
      <id>development</id>
      <repositories>
        <repository>
          <id>miSupplementaryMavenStuff</id>
          <name>Supplementary MI archetypes and artifacts</name>

          <!-- The actual »payload« referring to the MI Maven server hosting additional archetypes and artifacts -->
          <url>https://maven.mi.hdm-stuttgart.de/nexus/repository/mi-maven</url>

          <releases><enabled>true</enabled></releases>
          <snapshots><enabled>true</enabled></snapshots>
        </repository>
      </repositories>
    </profile>
  </profiles>

  <activeProfiles>
    <activeProfile>development</activeProfile>
  </activeProfiles>

</settings>

Note

https://maven.mi.hdm-stuttgart.de/nexus/repository/mi-maven refers to a Sonatype Nexus repository manager instance hosting supplementary Maven archetypes and artifacts.

Figure 276. CLI testing mi-maven-archetype-quickstart

mvn --batch-mode -e archetype:generate \
  -DgroupId=de.hdm_stuttgart.mi.sd1 -DartifactId=second -Dversion=0.9 \
  -DarchetypeGroupId=de.hdm_stuttgart.mi -DarchetypeArtifactId=mi-maven-archetype-quickstart -DarchetypeVersion=2.3
[INFO] Error stacktraces are turned on.
[INFO] Scanning for projects...
      ...
[INFO] BUILD SUCCESS ...

Figure 277. CLI archetype details

mvn --batch-mode ❶ -e archetype:generate ❷ \
                                              \
 -DarchetypeGroupId=de.hdm_stuttgart.mi \ ❸
 -DarchetypeArtifactId=mi-maven-archetype-quickstart \
 -DarchetypeVersion=2.3 \
                        \
 -DgroupId=de.hdm_stuttgart.mi.sd1 ❹ \
 -DartifactId=first  \
 -Dversion=0.9

❶	During project generation Maven shall work in batch mode not asking for user input.
❷	Create a Maven project using an archetype being specified by ❸.
❸	Our desired archetype is being addressed by its three »coordinates« on the MI Maven repository server: archetypeGroupId de.hdm_stuttgart.mi typically referring to the hosting institution. archetypeArtifactId mi-maven-archetype-quickstart denoting a piece of software within a hosting institution. archetypeVersion 2.3 identifying a specific version of the software in question.
❹	Likewise we do have three parameters uniquely defining our own software product's Maven identity: groupId. This value also defines the projects base package name as being explained in the section called “Packages”: `package de.hdm_stuttgart.mi.sd1; ... public class ...` Note You are thus strongly advised not using operator symbols like - in groupId definitions. For this reason the current example features `de.hdm_stuttgart.mi.sd1` rather than `de.hdm-stuttgart.mi.sd1`. artifactId version

exercise No. 116

DNS inflicted groupId / package names clashes

Regarding the extended explanations of Figure 277, “CLI archetype details ” we consider two different organisations https://hdm-stuttgart.de and https://hdm_stuttgart.de. Following the »coordinate« recommendations both organizations would then choose the common conflicting groupId de.hdm_stuttgart leading to possible Maven artifact clashes. May this conflict actually happen?

Tip

Read about valid DNS domain names.

The conflict cannot occur since the underscore is being disallowed in domain names according to the DNS specification. Thus hdm_stuttgart.de is an illegal domain name. Mapping hyphens appearing in domain names to underscores in packages therefore works perfectly.

Figure 278. Generated project layout

> cd first        # Enter project directory
> find . -type f  # Search recursively for files
./.gitignore ❶
./src/main/java/de/hdm_stuttgart/mi/sd1/App.java ❷
./pom.xml ❸

❶	Exclude specific files from version git based control.
❷	Java™ source file containing an executable `main()` class.
❸	The Project Object Model file defining build rules.

Figure 279. Maven compile

> mvn compile
[INFO] Scanning for projects...
       ...
[INFO] Building first 0.9
   ...
[INFO] Changes detected - recompiling the module!
[INFO] Compiling 1 source file to /ma/goik/first/target/classes
[INFO] --------------------------------------------------------
[INFO] BUILD SUCCESS

Figure 280. Compilation file view

> find target/classes -type f
./target/classes/de/hdm_stuttgart/mi/sd1/App.class
...

Figure 281. Execution

> cd target/classes ❶
> java de.hdm_stuttgart.mi.sd1.App ❷
Hi there, let's have
fun learning Java! ❸

❶

Change to base directory containing compiled Java™ classes.

❷

Application execution. Note:

Our App class is being prefixed by the package name de.hdm_stuttgart.mi.sd1 defined by the groupId parameter in Figure 277, “CLI archetype details ”.

❸

The expected output result.

Note

Executing this particular class requires a configuration in our project's pom.xml file:

...
<archive>
  <manifest>
    <mainClass>de.hdm_stuttgart.mi.sd1.test.ShowReachedPoints</mainClass>
  </manifest>
</archive> ...

Figure 282. Maven package

> mvn package
...
 T E S T S
...
Tests run: 1, Failures: 0, Errors: 0, Skipped: 0
   ...
[INFO] Building jar: /ma/goik/first/target/first-0.9.jar
...
[INFO] Replacing /ma/goik/first/target/first-0.9.jar with 
         /ma/goik/first/target/first-0.9-shaded.jar
...
[INFO] BUILD SUCCESS

Figure 283. Executing Java™ archive first-0.9.jar

java -jar target/first-0.9.jar
Hi there, let's have
fun learning Java!

Remark: This will execute HelloWorld.class being contained in first-0.9.jar.

exercise No. 117

Details on execution

In Figure 283, “Executing Java™ archive first-0.9.jar ” we saw successful execution of:

java -jar target/first-0.9.jar

How does this actually work? There might be multiple executable classes containing main() methods within a given project? How is de/hdm_stuttgart/mi/sd1/App.class being selected for execution?

Tip

Have a closer look on your project's pom.xml. Also unzip your generated first-0.9.jar file to examine the contained file META-INF/MANIFEST.MF.

Our pom.xml defines a single class which must contain a public static void main(String[] args) method:

<project xmlns="http://maven.apache.org/POM/4.0.0" ...>
  <modelVersion>4.0.0</modelVersion>
  ...
    <manifestEntries>
       <Main-Class>de.hdm_stuttgart.mi.sd1.App</Main-Class>
    </manifestEntries>
  ...
</project>

The Maven package processing step wraps this class name into the generated first-0.9.jar archive's manifest file META-INF/MANIFEST.MF:

> cat META-INF/MANIFEST.MF 
Manifest-Version: 1.0
Archiver-Version: Plexus Archiver
Created-By: Apache Maven 3.5.2
Built-By: goik
Build-Jdk: 10.0.2
Main-Class: de.hdm_stuttgart.mi.sd1.App

This allows the Java™ runtime to choose the class to be executed.

Figure 284. Maven javadoc:javadoc

> mvn javadoc:javadoc
[INFO] Scanning for projects...
...
Generating /ma/goik/First/target/site/apidocs/allclasses-noframe.html...
Generating /ma/goik/First/target/site/apidocs/index.html...
Generating /ma/goik/First/target/site/apidocs/overview-summary.html...
Generating /ma/goik/First/target/site/apidocs/help-doc.html...

See e.g. class String documentation.

Figure 285. Maven clean

> mvn clean
...
[INFO] 
[INFO] --- maven-clean-plugin:2.5:clean (default-clean) @ first ---
[INFO] Deleting /ma/goik/first/target
[INFO] ------------------------------------------------------------------------
[

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