Generate JAXB classes with Maven based on multiple schema’s

Earlier, we blogged about generating JAXB classes based on XSD files. However, sometimes we need multiple configurations with multiple XSD files. Previous blog posts did not cover this topic, so I thought I’d cover it in a seperate post.

The solution is to add multiple executions for the maven-jaxb2-plugin plugin. Each execution is bound to the generate-resources phase of the Maven build process. Now, each time the project is build, the executions kick in and the JAXB classes are generated.

Behold the following configuration:

<plugin>
	<groupId>org.jvnet.jaxb2.maven2</groupId>
	<artifactId>maven-jaxb2-plugin</artifactId>
	<version>0.7.0</version>
	<executions>
		<execution>
			<id>One</id>
			<phase>generate-resources</phase>
			<goals>
				<goal>generate</goal>
			</goals>
			<configuration>
				<schemaDirectory>${xsd.path}</schemaDirectory>
				<schemaIncludes>
					<include>schema-1.xsd</include>
					<include>schema-2.xsd</include>
				</schemaIncludes>
				<readOnly>true</readOnly>
				<removeOldOutput>true</removeOldOutput>
				<verbose>true</verbose>
				<extension>true</extension>
				<bindingDirectory>${jaxb.path}/</bindingDirectory>
				<bindingIncludes>
					<bindingInclude>jaxb-bindings-one.xml</bindingInclude>
				</bindingIncludes>
			</configuration>
		</execution>
		<execution>
			<id>Two</id>
			<phase>generate-resources</phase>
			<goals>
				<goal>generate</goal>
			</goals>
			<configuration>
				<schemaDirectory>${xsd.path}</schemaDirectory>
				<schemaExcludes>
					<exclude>schema-1.xsd</exclude>
					<exclude>schema-2.xsd</exclude>
				</schemaExcludes>
				<readOnly>true</readOnly>
				<removeOldOutput>false</removeOldOutput>
				<forceRegenerate>true</forceRegenerate>
				<verbose>true</verbose>
				<extension>true</extension>
				<bindingDirectory>${jaxb.path}/</bindingDirectory>
				<bindingIncludes>
					<bindingInclude>jaxb-bindings-two.xml</bindingInclude>
				</bindingIncludes>
			</configuration>
		</execution>
	</executions>
</plugin>	

Execution “One” will generate the JAXB classed for schema-1.xsd and schema-2.xsd (all other schema’s in path ${xsd.path} will not be processed) and uses jaxb-bindings-one.xml as bindingfile. Execution “Two” uses all other XSD’s in directory ${xsd.path} and uses jaxb-bindings-two.xml.

The trick is to use removeOldOutput properly. By default, this has the value true and will cause the generateDirectory to be deleted before the XJC binding compiler recompiles the source files. So, by default, the second execution will delete the result of the first execution before recompiling. Setting this to value false in the second execution solves our problem. Now, both configurations are executed successfully, each with its own binding file.