xjc-maven-plugin

NOTE: This plugin has been migrated to more generic jax-maven-plugin

The xjc executable is not present in the JDK as of version 11. However, the functionality of xjc is still available (right down to the command line arguments to that original executable) via external artifacts like org.glassfish.jaxb:jaxb-xjc.

xjc-maven-plugin sets up the classpath dependencies and passes the arguments you provide directly through to the com.sun.tools.xjc.Driver.run method.

The development of this plugin was motivated by problems with the jaxb2-maven-plugin with Java 9+. My company's codebase used jaxb2-maven-plugin in ~10 locations (always the xjc goal) and we wanted to move to OpenJDK 11+ given the EOL (unpaid) for Oracle Java 8 in January 2019.

Status: deployed to Maven Central

Features

Supports Java 8, 9, 10, 11+, gener:ates code from DTD or XSD
detects the -d destination directoy and auto-creates directory if does not exist
sets system properties
supports JAXB extensions
unit tested on Oracle JDK 8, 9, 10, 11 and OpenJDK 10, 11 (using Travis)

What about exec-maven-plugin?

It is possible to use exec-maven-plugin to call xjc via the java goal or exec goal to call XJCFacade.main (which calls com.sun.tools.xjc.Driver.run). There are problems though:

With exec:java you can call XJCFacade.main having setup the classpath with the jaxb-xjc dependency but XJCFacade.main calls System.exit so that after generating your classes the maven build is killed. Obviously terrible when you want stuff to happen after generating the classes!
With exec:exec you can call XJCFacade.main forked so that the System.exit doesn't kill the build but you have to build the classpath yourself (16 dependencies without maven to help you).
With both of the exec options you need to add a call to antrun-maven-plugin to create the destination directory if it doesn't exist.

Instead of these poor options, use xjc-maven-plugin!

How to build

mvn clean install

Getting started

Here's an example where we generate java classes with package dummy from an XSD file (pretty much a copy and paste from the unit test project):

<properties>
    <jaxb.generated>${project.build.directory}/generated-sources/jaxb</jaxb.generated>
</properties>
...
<plugin>
    <groupId>com.github.davidmoten</groupId>
    <artifactId>xjc-maven-plugin</artifactId>
    <version>VERSION_HERE</version>
    <executions>
        <execution>
            <id>gen</id>
            <!-- generate sources from the java.util.logging DTD -->
            <phase>generate-sources</phase>
            <goals>
                <goal>xjc</goal>
            </goals>
            <configuration>
                <systemProperties>
                    <enableExternalEntityProcessing>true</enableExternalEntityProcessing>
                </systemProperties>
                <execution>
                        <id>gen-from-xsd-kml</id>
                        <!-- generate sources from the kml 2.2 xsd -->
                        <phase>generate-sources</phase>
                        <goals>
                            <goal>xjc</goal>
                        </goals>
                        <configuration>
                            <systemProperties>
                                <enableExternalEntityProcessing>true</enableExternalEntityProcessing>
                            </systemProperties>
                            <arguments>
                                <!-- These are the arguments you would normally 
                                     have used with a call to xjc -->
                                <argument>-verbose</argument>
                                <!-- set the directory to hold generated classees -->
                                <argument>-d</argument>
                                <argument>${jaxb.generated}</argument>
                                <! -- set the directory containing schemas to convert to classes -->
                                <argument>${project.basedir}/src/main/jaxb/kml-2-2/xsd</argument>
                                <!-- set the directory containing jaxb bindings (customizations) -->
                                <argument>-b</argument>
                                <argument>${project.basedir}/src/main/jaxb/kml-2-2/bindings</argument>
                            </arguments>
                        </configuration>
                    </execution>
            </configuration>
        </execution>
    </executions>
</plugin>
<!-- ensure the generated sources are on the classpath (and in built jar) -->
<plugin>
    <groupId>org.codehaus.mojo</groupId>
    <artifactId>build-helper-maven-plugin</artifactId>
    <version>3.0.0</version>
    <executions>
        <execution>
            <id>add-source</id>
            <phase>generate-sources</phase>
            <goals>
                <goal>add-source</goal>
            </goals>
            <configuration>
                <sources>
                    <source>${jaxb.generated}</source>
                </sources>
            </configuration>
        </execution>
    </executions>
</plugin>

Output

Here's sample output from the plugin:

[INFO] --- xjc-maven-plugin:0.1.3-SNAPSHOT:xjc (gen-from-dtd) @ xjc-maven-plugin-test ---
[INFO] Starting xjc mojo
[INFO] destination directory (-d option) specified and does not exist, creating: /home/dxm/Development/ide/eclipse/workspace-4.7/xjc-maven-plugin/xjc-maven-plugin-test/target/generated-sources/jaxb
[INFO] setting up classpath for jaxb-xjc version 2.4.0-b180830.0438
parsing a schema...
compiling a schema...
[INFO] generating code
unknown location

dummy/Exception.java
dummy/Frame.java
dummy/Log.java
dummy/ObjectFactory.java
dummy/Param.java
dummy/Record.java
[INFO] xjc mojo finished

Note that the unknown location line is associated with the [INFO] generating code line and can be ignored (it's supposed to report where in the input files an error is coming from but this INFO-level log line is not associated with a real problem so no location is included).

If you want more detail including all classpath items for the xjc call then call:

mvn clean install -X

Arguments

See the Java 8 xjc documentation for descriptions of the arguments to pass to xjc using the plugin.

Note that if you don't specify the -d destination directory then generated source will be placed in the root of the project directory. In short, always specify the -d parameter.

Using JAXB extensions

If you add dependencies to the classpath used by xjc and include the -extension flag then you can customise the generated code. To add dependencies to the classpath of xjc use the <dependencies> element as below (let's add the jaxb2-basics dependency):

<plugin>
    <groupId>com.github.davidmoten</groupId>
    <artifactId>xjc-maven-plugin</artifactId>
    <version>${project.parent.version}</version>
    <dependencies>
        <dependency>
            <groupId>org.jvnet.jaxb2_commons</groupId>
            <artifactId>jaxb2-basics</artifactId>
            <version>1.11.1</version>
        </dependency>
    </dependencies>
    <executions>
    ...
    </executions>
</plugin>

A fully worked example that generates hashCode, equals and toString methods in generated classes is in xjc-maven-plugin-tests.

A big thank you to @Glebcher601 for contributing extension support!

Update the JAXB version used

For project maintainers, to use a new version of jaxb-xjc just update the glassfish.jaxb.version in the root pom.xml.

davidmoten / xjc-maven-plugin