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cdijava-ee-7

Why @Inject not work after import as a jar file to another project?

I have a Maven base Java EE project: core-project. In this project, I use @Inject and all things work as expected. But after importing this project as a dependency to another project, parent-project, the injected fields are null. Why, after importing a jar file to other project, the injection does not work?

Solution

  • If your fields are empty this means that matching beans can not be resolved. If they are in another package you need a file beans.xml (which can be empty).

    From The Java EE 6 Tutorial:

    Configuring a CDI Application

    An application that uses CDI must have a file named beans.xml. The file can be completely empty (it has content only in certain limited situations), but it must be present. For a web application, the beans.xml file must be in the WEB-INF directory. For EJB modules or JAR files, the beans.xml file must be in the META-INF directory.

    So make sure that there is a beans.xml in your core-projectand in parent-project. For Maven:

    from: https://stackoverflow.com/a/13057183/1838233

    For EJB and JAR packaging you should place the beans.xml in src/main/resources/META-INF/. For WAR packaging you should place the beans.xml in src/main/webapp/WEB-INF/

    Another reason could be that your Bean is annotated with @Alternative or @Specializes. In that case you need to specifiy the bean as alternative in the beans.xml:

    <beans ... >
    <alternatives>
        <class>sample.package.YourAlternativeBean</class>
    </alternatives>
</beans>

    See http://docs.oracle.com/javaee/6/tutorial/doc/gjsdf.html for more information on that.