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What are Maven Plugins?
Maven is actually a plugin execution framework where every task is actually done by plugins. Maven Plugins are generally used to −
- create jar file
- create war file
- compile code files
- unit testing of code
- create project documentation
- create project reports
A plugin generally provides a set of goals, which can be executed using the following syntax −
mvn [plugin-name]:[goal-name]
For example, a Java project can be compiled with the maven-compiler-plugin”s compile-goal by running the following command.
mvn compiler:compile
Plugin Types
Maven provided the following two types of Plugins −
| Sr.No. | Type & Description |
|---|---|
| 1 |
Build plugins
They execute during the build process and should be configured in the <build/> element of pom.xml. |
| 2 |
Reporting plugins
They execute during the site generation process and they should be configured in the <reporting/> element of the pom.xml. |
Following is the list of few common plugins −
| Sr.No. | Plugin & Description |
|---|---|
| 1 |
clean
Cleans up target after the build. Deletes the target directory. |
| 2 |
compiler
Compiles Java source files. |
| 3 |
surefire
Runs the JUnit unit tests. Creates test reports. |
| 4 |
jar
Builds a JAR file from the current project. |
| 5 |
war
Builds a WAR file from the current project. |
| 6 |
javadoc
Generates Javadoc for the project. |
| 7 |
antrun
Runs a set of ant tasks from any phase mentioned of the build. |
Example
We”ve used maven-antrun-plugin extensively in our examples to print data on console. Refer Build Profiles chapter. Let us understand it in a better way and create a pom.xml in C:MVNproject folder.
<project xmlns = "http://maven.apache.org/POM/4.0.0"
xmlns:xsi = "http://www.w3.org/2001/XMLSchema-instance"
xsi:schemaLocation = "http://maven.apache.org/POM/4.0.0
http://maven.apache.org/xsd/maven-4.0.0.xsd">
<modelVersion>4.0.0</modelVersion>
<groupId>com.companyname.projectgroup</groupId>
<artifactId>project</artifactId>
<version>1.0</version>
<build>
<plugins>
<plugin>
<groupId>org.apache.maven.plugins</groupId>
<artifactId>maven-antrun-plugin</artifactId>
<version>1.1</version>
<executions>
<execution>
<id>id.clean</id>
<phase>clean</phase>
<goals>
<goal>run</goal>
</goals>
<configuration>
<tasks>
<echo>clean phase</echo>
</tasks>
</configuration>
</execution>
</executions>
</plugin>
</plugins>
</build>
</project>
Next, open the command console and go to the folder containing pom.xml and execute the following mvn command.
C:MVNproject>mvn clean
Maven will start processing and displaying the clean phase of clean life cycle.
C:MVN>mvn clean
[INFO] Scanning for projects...
[INFO]
[INFO] ----------------< com.companyname.projectgroup:project >----------------
[INFO] Building project 1.0
[INFO] --------------------------------[ jar ]---------------------------------
[INFO]
[INFO] --- maven-clean-plugin:2.5:clean (default-clean) @ project ---
[INFO] Deleting C:MVNtarget
[INFO]
[INFO] --- maven-antrun-plugin:1.1:run (id.clean) @ project ---
[INFO] Executing tasks
[echo] clean phase
[INFO] Executed tasks
[INFO] ------------------------------------------------------------------------
[INFO] BUILD SUCCESS
[INFO] ------------------------------------------------------------------------
[INFO] Total time: 1.266 s
[INFO] Finished at: 2021-12-13T13:58:10+05:30
[INFO] ------------------------------------------------------------------------
C:MVN>
The above example illustrates the following key concepts −
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Plugins are specified in pom.xml using plugins element.
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Each plugin can have multiple goals.
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You can define phase from where plugin should starts its processing using its phase element. We”ve used clean phase.
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You can configure tasks to be executed by binding them to goals of plugin. We”ve bound echo task with run goal of maven-antrun-plugin.
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Maven will then download the plugin if not available in local repository and start its processing.
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