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Table of Contents

Maven License Plugin

Basically, when you are developing a project either in open source or in a company, you often need to add at the top of your source files a license to protect your work. I didn't find any maven plugin on Internet to help you maintain these license headers. By maintaining, i mean checking if the header is here or not, generating a report and of course having the possibility to update / reformat missing license headers.

Features:

Project:

Contributors

Maven Repository

Releases

Available in Maven Central Repository: http://repo1.maven.org/maven2/com/mycila/license-maven-plugin/

Snapshots

Available in OSS Repository: https://oss.sonatype.org/content/repositories/snapshots/com/mycila/license-maven-plugin/

Plugin declaration

<plugin>
    <groupId>com.mycila</groupId>
    <artifactId>license-maven-plugin</artifactId>
    <version>X.Y.ga</version>
    <configuration>
        <header>com/mycila/maven/plugin/license/templates/APACHE-2.txt</header>
        <properties>
            <owner>Mycila</owner>
            <email>mathieu.carbou@gmail.com</email>
        </properties>
        <excludes>
            <exclude>**/README</exclude>
            <exclude>src/test/resources/**</exclude>
            <exclude>src/main/resources/**</exclude>
        </excludes>
    </configuration>
    <executions>
        <execution>
            <goals>
                <goal>check</goal>
            </goals>
        </execution>
    </executions>
</plugin>

Documentation

Detailed Maven documentation

The detailed Maven Plugin Documentation generated for each build is available here:

WARNING: there is good chances the latest version is greater than latest documentation, if nothing has changed concerning the plugin configurations.

Goals

Configuration

The table below shows all the available options you can use in the configure section of the plugin. A lot of are also available from the command-line. To use them, simply launch your maven command with a property like -Dproperty=value (i.e. mvn license:check -Dlicense.header=src/etc/header.txt)

All plugin configuration options are described in the Detailed Maven documentation but here are some details.

License templates

Maven license plugin comes with the following license templates:

You can find those license templates with preconfigured placeholders here

Properties and placeholders

Properties which can be used as placeholder comes from:

Properties are built per-document. You can provide a dependency JAR file to the plugin which contains an implementation of com.mycila.maven.plugin.license.PropertiesProvider:

public interface PropertiesProvider {
    Map<String, String> getAdditionalProperties(AbstractLicenseMojo mojo, Properties currentProperties, Document document);
}

You have access to the Mojo, the current built properties and the document being checked or formatted. The plugin uses the JDK ServiceLoader mechanism to find all PropertiesProvider implementations on the plugin classpath and execute them. Thus, just add the implementation class name in the file META-INF/services/com.mycila.maven.plugin.license.PropertiesProvider in your JAR file.

Supported comment types

The plugin has been designed so that it is very easy to add new supports for new sorts of comment. The plugin currently support these types of comment:

    /**
     * My comment
     */
    <!--
        My comment
    -->
    <!-- My first comment  -->
    <!-- My second comment -->

(automatically right-adjusts the closing comment)

    ~~ My comment
    # My comment
    -# My comment
    @REM My comment
    ====
        My comment
    ====

(4 spaces, then the lines of the header)

    --
    -- test comment
    --
    <%--
        comment
    --%>
    <#--
        comment
    -->
    [#ftl ...]
    [#--
        comment
    --]
    #*
        comment
    *#
    ;
    ; comment
    ;
    {*
     * comment
     *}
    '
    ' comment
    '
    !
    ! comment
    !
    /*
     * comment
     */
    <!---
        comment
    --->
    % comment
    %%%
    %%% comment
    %%%
    !!!
    !!! comment
    !!!
    --[[
    comment
    ]]
    <%
    ' comment
    %>
    /*
     * comment
     */

(inserted after the <?php> tag)

    //
    // comment
    //

Custom mapping

The plugin enables you to add any other mapping you want.* I.e., if you are developing a Tapestry web application, you may need to add license header in .jwc files and .application files. since these files are xml files, you only need to add in your project pom the following mapping for the license-maven-plugin:

<mapping>
    <jwc>XML_STYLE</jwc>
    <application>XML_STYLE</application>
    <apt.vm>DOUBLETILDE_STYLE</apt.vm>
    <vm>SHARPSTAR_STYLE</vm>
    <apt>DOUBLETILDE_STYLE</apt>  
</mapping>

You can use composed-extensions like *.apt.vm and redefine them, but you will have to nake sure that the mapping of apt.vm is before the mapping of the vm extension. The order in the mapping section is important: extensions seen first take precedence.

Changing header style definitions

In license-maven-plugin, each header style is defined by patterns to detect it and also strings to insert it correctly in files. If we take for example the Javadoc style header definition. It is defined as follow:

<?xml version="1.0" encoding="ISO-8859-1"?>
<additionalHeaders>
    <javadoc_style>
        <firstLine>/**</firstLine>
        <beforeEachLine> * </beforeEachLine>
        <endLine> */</endLine>
        <afterEachLine></afterEachLine>
        <!--skipLine></skipLine-->
        <firstLineDetectionPattern>(\s|\t)*/\*.*$</firstLineDetectionPattern>
        <lastLineDetectionPattern>.*\*/(\s|\t)*$</lastLineDetectionPattern>
        <allowBlankLines>false</allowBlankLines>
        <isMultiline>true</isMultiline>
        <padLines>false</padLines>
    </javadoc_style>
</additionalHeaders>

And for XML:

<?xml version="1.0" encoding="ISO-8859-1"?>
<additionalHeaders>
    <javadoc_style>
        <firstLine><![CDATA[<!--\n]]></firstLine>
        <beforeEachLine>    </beforeEachLine>
        <endLine><![CDATA[-->]]></endLine>
        <afterEachLine></afterEachLine>
        <skipLine><![CDATA[^<\?xml.*>$]]></skipLine>
        <firstLineDetectionPattern><![CDATA[(\s|\t)*<!--.*$]]></firstLineDetectionPattern>
        <lastLineDetectionPattern><![CDATA[.*-->(\s|\t)*$]]></lastLineDetectionPattern>
        <allowBlankLines>false</allowBlankLines>
        <isMultiline>true</isMultiline>
        <padLines>false</padLines>
    </javadoc_style>
</additionalHeaders>

With the headerDefinitions option, you can redefine existing header styles and also add some if we do not support the styles you want yet. You just have to provide a list of headerDefinition containing a resource name. Like the header, the resource is searched on the file system, in the classpath of the project, the plugin and also as a URL.

Full Example

This page will show you how you can define extended header definitions to fit your needs. The next example will define headers in a region area allowed in C# source files:

<?xml version="1.0" encoding="ISO-8859-1"?>
<additionalHeaders>
    <csregion_style>
        <firstLine>#region LicenseEOL/**</firstLine>
        <beforeEachLine> * </beforeEachLine>
        <endLine> */EOL#endregion</endLine>
        <firstLineDetectionPattern>#region.*^EOL/\*\*.*$</firstLineDetectionPattern>
        <lastLineDetectionPattern>\*/EOL#endregion"</lastLineDetectionPattern>
        <allowBlankLines>true</allowBlankLines>
        <isMultiline>true</isMultiline>
    </csregion_style>
</additionalHeaders>

You now have to add this new header definition file to the plugin configuration. It is done as the following in your pom:

<headerDefinitions>
   <headerDefinition>yourdefinition.xml</headerDefinition>
</headerDefinitions>

You now have to add the new mapping for *.cs files to use this new header definition. It is done as the following in your pom:

<mapping>
    <cs>CSREGION_STYLE</cs>
</mapping>

And it should generate headers like:

#region License
/**
 * Copyright (C) 2008 http://code.google.com/p/license-maven-plugin/
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *         http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */
#endregion