check your pom, there should be something along these line:
<plugin>
<groupId>org.jvnet.jaxb2.maven2</groupId>
<artifactId>maven-jaxb2-plugin</artifactId>
<version>0.8.1</version> <!-- I used version 0.8.1 since 0.8.2 is bugged and it throws the Exception
"Illegal pattern character 'g' "when using italian locale -->
<executions>
<execution>
<id>wsdl-generation</id>
<goals>
<goal>generate</goal>
</goals>
<configuration>
<schemaDirectory>src/main/resources/wsdl</schemaDirectory>
<schemaIncludes>
<include>*.xsd</include>
</schemaIncludes>
<extension>true</extension>
<!-- Specify binding directory where we put customization for the
generated classes -->
<bindingDirectory>src/main/resources/binding</bindingDirectory>
<bindingIncludes>
<include>*.xjb</include>
</bindingIncludes>
</configuration>
</execution>
</executions>
</plugin>
with slight difference to match with your wsdl location/binding (if any)/etc..
Classes are generated under target, so ensure that you add them to the classpath (simply after you run the generate sources, do a maven -->update project and it should take care of it if i recall correctly)..
You might want to do a right click --> run as --> maven generate sources in case it seems it's not working properly.