maven.md

mvn commands

General Syntax

• mvn [life cycle commands] [plugin:target] [-Doption=value] [dots]

Debug

• mvn -X - Will print more logs

Cores to use

• mvn -T 1C - Create threads as much as the number of cores
• mvn -T 2C - Create threads double the number of cores

Create a new project in interactive mode

• mvn archetype:generate

Create a new project in non-interactive mode

• mvn archetype:generate -DgroudId=<Artifact Group | Package name> -DartifactId=<Artifact ID | Project name> -DinteractiveMode=false

Create a new project in non-interactive mode based on existing template

• mvn archetype:generate -DgroudId=<Artifact Group | Package name> -DartifactId=<Artifact ID | Project name> -DarchetypeArtifactId=<Archetype Artifact ID | Existing maven template project ID> -DinteractiveMode=false

Life cycle execution

Run the following commands inside the folder containing pom.xml files

• mvn clean
• mvn test
• mvn compile
• mvn package
• mvn install - Install Artifact locally
  • -o - Run in offline mode

Skip Testing

• mvn install -Dmaven.test.skip=true
  • Execute 'install' life cycle without running tests
  • Doesn't compile test files at all
• mvn install -DskipTests
  • Short alternative to skip tests
  • Here test files are compiled, but it is not run

Run a single unit test

• mvn -Dtest=TestClass#testMethod test

Maven Profiles

• Run with particular profile - mvn -Pprod
• Ref: http://maven.apache.org/guides/introduction/introduction-to-profiles.html

Command line options

• -B - Runs Maven in batch mode. It avoids Maven's reporting of downloading progress.
• -e - Configures Maven to report detailed information about errors
• -pl - Run a module alone in multi-module project setup
  • -am - Additional parameter to resolve local dependency in multi-module project setup. E.g. mvn -pl clean install -am module-b

Analyze dependencies

• mvn dependency:analyze - Helps to get information on "Used undeclared dependencies", "Unused declared dependencies" etc.
• mvn -Dverbose dependency:tree - To see dependency tree
  • -Dverbose - This will show options not displayed because of duplication
  • -Dincludes=[group]:[artifact_name]:[type]:[version] - E.g., mvn -Dverbose dependency:tree -Dincludes=:hibernate*. Use wild card * to cover different possibilities
  • Ref: filtering-the-dependency-tree
  • Ref: resolving-conflicts-using-the-dependency-tree
• mvn versions:display-dependency-updates

Relative dependency comparison

• Run mvn compile dependency:tree >> temp_v01.txt to store dependency tree to the file
• Then make the necessary changes
• And, run mvn compile dependency:tree >> temp_v02.txt to store new dependency tree to the file
• Compare 2 files to see the difference

Update snapshots

• mvn -U - Check for updated snapshots on remote repositories

Install a downloaded or local jar into maven local repository

• mvn install:install-file -Dfile=my-jar.jar -DgroupId=com.shaunthomas999 -DartifactId=my-jar -Dversion=LOCAL -Dpackaging=jar

Download a artifact from repo like Nexus, Artifactory etc.

• mvn dependency:copy -Dartifact="com.shaunthomas999.project:my-sample-project:RELEASE:jar" -DoutputDirectory=.

Maven Dependencies

Scope

<scope> values

1. compile - default - transitive

2. provided - provided at runtime by JDK or container - not transitive (available in compile and test only). E.g. servlet API

3. system - like provided but dependency path should be explicitly specified by <systemPath> property

   <dependency>
       <groupId>com.baeldung</groupId>
       <artifactId>custom-dependency</artifactId>
       <version>1.3.2</version>
       <scope>system</scope>
       <systemPath>${project.basedir}/libs/custom-dependency-1.3.2.jar</systemPath>
   </dependency>

4. runtime - required at runtime - not in compile time but in test and runtime. E.g. JDBC driver

5. test - required for testing - not transitive. E.g., JUnit

6. import - only available for dependency type <type>pom</type>. Replace declaration with effective pom that is imported.

provided and test scope will never end-up in main project

References

• https://www.baeldung.com/maven-dependency-scopes
• https://maven.apache.org/guides/introduction/introduction-to-dependency-mechanism.html

Bump version

• mvn versions:set -DgenerateBackupPoms=false -DnewVersion=<Put_New_Version_Here>

Deploy

• mvn deploy

Mirros

• Ref: https://maven.apache.org/guides/mini/guide-mirror-settings.html

Settings

• Ref: https://maven.apache.org/settings.html

Cheatsheet - Look at Google Drive