Add UML diagrams (using PlantUML) to Javadocs. Extends the standard Java doclet.

The inspiration for this project is better communication between the developers on my team. We want to follow the principles of DDD and Model-Driven Design (https://www.amazon.ca/Domain-Driven-Design-Tackling-Complexity-Software/dp/0321125215/ref=sr_1_1?s=books&ie=UTF8&qid=1475876769&sr=1-1&keywords=domain+driven+design) and automatically generating class diagrams is a key part of that approach.

Generates three types of diagrams:

• Overview: Shows all classes within all packages. Click on a class to get to the Javadoc for that class. Click on a package to get to the Javadoc for that package.
• Package: Shows all of the classes within a package, and the relationships between them. Does not show relationships with classes outside the package.
• Class: Shows all of the relationships with other classes. If the other class is in the same package, it is shown in yellow (default color). If in another package within the set of packages, it is shown in white. If the other class is outside any of the packages, it is shown in grey.

The relationships with other classes are determined by what the Javadoc API provides, which is from the attribute and method declarations for a class. Any usages that are buried within code will not be shown. If I think a relationship is important enough to be shown, I will make it explicit (e.g. add an attribute to the other class).

Layouts can appear strange. This is due to the use of GraphViz. Good enough for my purposes, although there are other options that are being explored (http://plantuml.sourceforge.net/qa/?qa=4842/graphviz-is-not-good-enough).

• GraphViz (as required by PlantUML).
• Java 8 (easy enough to backport to earlier versions).

NOTE: The doclet tool was completely changed in Java 9; uml-java-doclet will not work with any JDK later than 8.

Use http://jitpack.io to automatically build and install the JAR file. Add the JitPack repository to your POM:

<repositories>
	<repository>
	    <id>jitpack.io</id>
	    <url>https://jitpack.io</url>
	</repository>
</repositories> 

Note: Not published to Maven Central; this is a much easier alternative.

To generate UML diagrams for your own project, add the following to your POM:

<build>
    <plugins>
        <plugin>
            <groupId>org.apache.maven.plugins</groupId>                                  
            <artifactId>maven-javadoc-plugin</artifactId>
            <version>3.2.0</version>
            <configuration>
                <doclet>info.leadinglight.umljavadoclet.UmlJavaDoclet</doclet>
                <docletArtifact>
                    <groupId>com.github.gboersma</groupId>
                    <artifactId>uml-java-doclet</artifactId>
                    <version>1.1</version>
                </docletArtifact>
                <useStandardDocletOptions>true</useStandardDocletOptions>
                <additionalOptions>
                    <!-- Specify each diagram option here as an additionOption tag. -->
                </additionalOptions>
            </configuration>
        </plugin>
    </plugins>
</build>

Note: Version 3+ of the maven-javadoc-plugin uses the additionalOptions tag to specify additional javadoc tags. The previous additionalparam tag no longer works correctly. Be sure to upgrade your POMs accordingly.

Options for the diagrams are specified as additionalOption tags in the POM.

• To generate the Javadoc to a different folder, refer to: https://maven.apache.org/plugins-archives/maven-javadoc-plugin-3.2.0/examples/output-configuration.html for how to use specify the standard doclet option.

Many thanks to the folks at PlantUML (https://github.com/plantuml/plantuml) for their fantastic support. Thanks to @bcopy for the pointer to jitpack.

Copyright 2016 Gerald Boersma

Licensed under the Apache License, Version 2.0 (the "License"); you may not use this 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.