Understanding and definition of maven-plugin

Article directory

• 1. Definition and configuration of plugin
• • 1. Custom plugin
  • 2. Bind goal to maven execution cycle
  • 3. Define the default maven cycle of the goal
  • 4. The command executes the execution defined by the current pom
  • 5. The plugin runs with the latest dependencies
  • 6. The plugin configuration does not take effect in the child pom
• 2. Expansion

1. Definition and configuration of plugin

1. Custom plugin

Reference: official website

• basic definition

Among them, @Mojo.name is the name of the goal, and @Parameter is the definition configured in configuraiton

@Mojo( name = "query" ) //Define the name of the goal
public class MyQueryMojo
    extends AbstractMojo
{<!-- -->
    @Parameter(property = "query.url", required = true)
    private String url;
 
    @Parameter(property = "timeout", required = false, defaultValue = "50")
    private int timeout;
 
    @Parameter(property = "options")
    private String[] options;
 
    public void execute()
        throws MojoExecutionException
    {<!-- -->
        ...
    }
}

use plugin

<project>
  ...
  <build>
    <plugins>
      <plugin>
        <artifactId>maven-myquery-plugin</artifactId>
        <version>1.0</version>
        <configuration>
          <url>http://www.foobar.com/query</url>
          <timeout>10</timeout>
          <options>
            <option>one</option>
            <option>two</option>
            <option>three</option>
          </options>
        </configuration>
      </plugin>
    </plugins>
  </build>
  ...
</project>

• Define configuration item type conversions

Conversion of configuration values to concrete type configuration items

Parameter Class	Conversion from String
Boolean	Boolean.valueOf(String)
Byte	Byte.decode (String)
Character	Character.valueOf(char) of the first character in the given string
Class	Class.forName(String)
java.util.Date	SimpleDateFormat.parse(String) for the following patterns: yyyy-MM-dd hh:mm:ss.S a, yyyy-MM-dd hh:mm:ssa, yyyy-MM-dd HH:mm:ss.S or yyyy-MM-dd HH:mm:ss
Double	Double.valueOf(String)
Enum	Enum.valueOf(String)
java.io.File	new File(String) with the file separators normalized to File. separatorChar. In case the file is relative, is is made absolute by prefixing it with the project’s base directory.
Float	Float. valueOf(String)
Integer	Integer.decode(String)
Long	Long.decode(String)
Short	Short.decode(String)
String	n/a
StringBuffer	new StringBuffer(String)
StringBuilder	new StringBuilder( String)
java.net.URI	new URI(String)
java.net.URL	new URL(String)

• When the configuration item is a complex object

It is reflected by the indentation of the xml tag

<project>
...
<configuration>
  <person>
    <firstName>Jason</firstName>
    <lastName>van Zyl</lastName>
  </person>
</configuration>
...
</project>

• The configuration item is the interface

Concretely reflected by the implementation class

<project>
...
<configuration>
  <person implementation="com.mycompany.mojo.query.SuperPerson">
    <firstName>Jason</firstName>
    <lastName>van Zyl</lastName>
  </person>
</configuration>
...
</project>

• Configuration items are collections

public class MyAnimalMojo
    extends AbstractMojo
{<!-- -->
    @Parameter(property = "animals")
    private List<String> animals;
 
    public void execute()
        throws MojoExecutionException
    {<!-- -->
        ...
    }
}

<project>
  ...
  <build>
    <plugins>
      <plugin>
        <artifactId>maven-myanimal-plugin</artifactId>
        <version>1.0</version>
        <configuration>
          <animals>
            <animal>cat</animal>
            <animal>dog</animal>
            <animal>aardvark</animal>
          </animals>
        </configuration>
      </plugin>
    </plugins>
  </build>
  ...
</project>

<project>
  ...
  <build>
    <plugins>
      <plugin>
        <artifactId>maven-myanimal-plugin</artifactId>
        <version>1.0</version>
        <configuration>
          <animals>cat,dog,aardvark</animals>
        </configuration>
      </plugin>
    </plugins>
  </build>
  ...
</project>

• The configuration item is map

...
@Parameter
    private Map<String,String> myMap;
...

<project>
...
  <configuration>
    <myMap>
      <key1>value1</key1>
      <key2>value2</key2>
    </myMap>
  </configuration>
...
</project>

• The configuration item is properties

...
    @Parameter
    private Properties myProperties;
...

<project>
...
  <configuration>
    <myProperties>
      <property>
        <name>propertyName1</name>
        <value>propertyValue1</value>
      </property>
      <property>
        <name>propertyName2</name>
        <value>propertyValue2</value>
      </property>
    </myProperties>
  </configuration>
...
</project>

2. Bind goal to maven execution cycle

• bound to a single goal

Note: The second goal is not bound (unless it is defined with a default binding period)

<project>
  ...
  <build>
    <plugins>
      <plugin>
        <artifactId>maven-myquery-plugin</artifactId>
        <version>1.0</version>
        <executions>
          <execution>
            <id>execution1</id>
            <phase>test</phase>
            <configuration>
              <url>http://www.foo.com/query</url>
              <timeout>10</timeout>
              <options>
                <option>one</option>
                <option>two</option>
                <option>three</option>
              </options>
            </configuration>
            <goals>
              <goal>query</goal>
            </goals>
          </execution>
          <execution>
            <id>execution2</id>
            <configuration>
              <url>http://www.bar.com/query</url>
              <timeout>15</timeout>
              <options>
                <option>four</option>
                <option>five</option>
                <option>six</option>
              </options>
            </configuration>
            <goals>
              <goal>query</goal>
            </goals>
          </execution>
        </executions>
      </plugin>
    </plugins>
  </build>
  ...
</project>

• bound to multiple cycles

<project>
  ...
  <build>
    <plugins>
      <plugin>
        ...
        <executions>
          <execution>
            <id>execution1</id>
            <phase>test</phase>
            ...
          </execution>
          <execution>
            <id>execution2</id>
            <phase>install</phase>
            <configuration>
              <url>http://www.bar.com/query</url>
              <timeout>15</timeout>
              <options>
                <option>four</option>
                <option>five</option>
                <option>six</option>
              </options>
            </configuration>
            <goals>
              <goal>query</goal>
            </goals>
          </execution>
        </executions>
      </plugin>
    </plugins>
  </build>
  ...
</project>

3. Define the default maven cycle of the goal

@Mojo( name = "query", defaultPhase = LifecyclePhase.PACKAGE )
public class MyBoundQueryMojo
    extends AbstractMojo
{<!-- -->
    @Parameter(property = "query.url", required = true)
    private String url;
 
    @Parameter(property = "timeout", required = false, defaultValue = "50")
    private int timeout;
 
    @Parameter(property = "options")
    private String[] options;
 
    public void execute()
        throws MojoExecutionException
    {<!-- -->
        ...
    }
}

It can also be changed to another cycle, and the original cycle will no longer take effect

<project>
  ...
  <build>
    <plugins>
      <plugin>
        <artifactId>maven-myquery-plugin</artifactId>
        <version>1.0</version>
        <executions>
          <execution>
            <id>execution1</id>
            <phase>install</phase>
            <configuration>
              <url>http://www.bar.com/query</url>
              <timeout>15</timeout>
              <options>
                <option>four</option>
                <option>five</option>
                <option>six</option>
              </options>
            </configuration>
            <goals>
              <goal>query</goal>
            </goals>
          </execution>
        </executions>
      </plugin>
    </plugins>
  </build>
  ...
</project>

4. The command executes the execution defined by the current pom

mvn myquery:query@execution1

5. Plugin runs with the latest dependencies

<project>
  ...
  <build>
    <plugins>
      <plugin>
        <groupId>org.apache.maven.plugins</groupId>
        <artifactId>maven-antrun-plugin</artifactId>
        <version>1.2</version>
        ...
        <dependencies>
          <dependency>
            <groupId>org.apache.ant</groupId>
            <artifactId>ant</artifactId>
            <version>1.7.1</version>
          </dependency>
          <dependency>
            <groupId>org.apache.ant</groupId>
            <artifactId>ant-launcher</artifactId>
            <version>1.7.1</version>
          </dependency>
         </dependencies>
      </plugin>
    </plugins>
  </build>
  ...
</project>

6. The plug-in configuration does not take effect in the child pom

The default is propagated, just set inherited=false

<project>
  ...
  <build>
    <plugins>
      <plugin>
        <groupId>org.apache.maven.plugins</groupId>
        <artifactId>maven-antrun-plugin</artifactId>
        <version>1.2</version>
        <inherited>false</inherited>
        ...
      </plugin>
    </plugins>
  </build>
  ...
</project>

2. Extension

• Plug-in usage recommendation

The parent pom defines version management, and the child pom directly references it

<project>
  ...
  <build>
    <!-- To define the plugin version in your parent POM -->
    <plugin Management>
      <plugins>
        <plugin>
          <groupId>org.apache.maven.plugins</groupId>
          <artifactId>maven-resources-plugin</artifactId>
          <version>3.3.1</version>
        </plugin>
        ...
      </plugins>
    </pluginManagement>
    <!-- To use the plugin goals in your POM or parent POM -->
    <plugins>
      <plugin>
        <groupId>org.apache.maven.plugins</groupId>
        <artifactId>maven-resources-plugin</artifactId>
      </plugin>
      ...
    </plugins>
  </build>
  ...
</project>

• The goal corresponding to the default cycle of maven

validate
initialize
generate-sources
process-sources
generate-resources
process-resources
compile
process-classes
generate-test-sources
process-test-sources
generate-test-resources
process-test-resources
test-compile
process-test-classes
test
prepare-package
package
pre-integration-test
integration-test
post-integration-test
verify
install
deploy