Java EE 7 - @Decorator，@Stateless和@PersistenceContext = nullpointerException [英] Java EE 7 - @Decorator, @Stateless and @PersistenceContext = nullpointerException

问题描述

我在java ee 7（glassfish 4）中使用了decorator模式。

I'm using decorator pattern in java ee 7 (glassfish 4).

我有这个装饰器

@Decorator
public class FooIndexer implements FooService {

    @Inject
    @Delegate
    FooService fooService;

    private Logger logger = Logger.getLogger(FooIndexer.class.getName());

    //@Inject
    //Indexer indexer;

    @Override
    public Foo create(Foo foo, boolean index) {

        fooService.create(foo, index);

        if (index) {
            System.out.println("Im in");
        }

        return foo;
    }

}

这个ejb类

@Stateless(name = "fooService")
@TransactionAttribute(TransactionAttributeType.REQUIRES_NEW)
@DeclareRoles({"ADMINISTRATOR", "USER"})
public class FooServiceImpl implements FooService {

    @PersistenceContext(unitName = "foo")
    private EntityManager em;

    @Resource(lookup="java:comp/EJBContext")
    private SessionContext ctx;

    /** CRUD **/
    @RolesAllowed("ADMINISTRATOR")
    public Foo create(Foo foo, boolean index) {

        Principal cp = ctx.getCallerPrincipal();

        System.out.println(cp.getName());

        em.persist(foo);

        return foo;
    }
}

当我使用这个装饰器模式时，EJB中的EntityManager null（没有装饰器，一切顺利）。我认为是因为装饰器使用@Inject而不是@EJB注解（@EJB注释不能在@Decorator中使用），并且EntityManager没有被注入。

When I use this decorator pattern, EntityManager in EJB is null (without decorator, everything goes fine). I supose is because of decorator use @Inject instead of @EJB annotation (@EJB annotation can't be used in @Decorator), and EntityManager is not being injected.

但是，如何使用@decorator注入实体管理员？

But, what can I do to get entitymanager will be injected using @decorator?

谢谢

Thank you

推荐答案

尝试在META-INF中添加一个空的beans.xml，这将激活CDI bean发现。我的项目有一个类似的问题。

Try adding an empty beans.xml in your META-INF, this will activate CDI bean discovery. I had a similar issue with my project.

请参阅oracle doc这里： http://docs.oracle.com/javaee/6/tutorial/doc/gjbnz.html

See oracle doc here : http://docs.oracle.com/javaee/6/tutorial/doc/gjbnz.html

您必须创建一个空的beans.xml文件，以向GlassFish Server指示您的应用程序是CDI应用程序。这个文件可能在某些情况下有内容，但不能像这样的简单应用程序。

You must create an empty beans.xml file to indicate to GlassFish Server that your application is a CDI application. This file can have content in some situations, but not in simple applications like this one.

http://docs.oracle.com/javaee/6/tutorial/doc/gjbju.html#gjcvh

祝你好运！

Alexander Kirilov

Alexander Kirilov

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