如何将EJB无状态会话Bean正确注入Web模块？

Question

作为Java EE的新手(但不是Java本身)我正在尝试构建一个非常简单的"企业应用程序",其中Hibernate作为JPA提供程序,JSF作为实际的UI框架.为此,我使用NetBeans 7和GlassFish 3.1.

{应用程序名称} -ejb:

我已经完成了从这些实体的数据库和本地sesssion bean生成实体类.Beans.xml已经到位.

@Stateless
public class QuestFacade extends AbstractFacade<Quest> implements QuestFacadeLocal {
    // some methods here as well as EntityManager injection ...
}

{应用程序名称} -war:

我已经创建了一个简单的POJO作为JSF页面的辅助bean.我用javax.inject.@Named和注释了它javax.enterprise.context.@SessionScoped.现在可以从JSF页面访问此辅助bean,并在访问实际页面时进行注入.Beans.xml也已就位.

@Named
@SessionScoped
public class QuestBean implements Serializable {

    @EJB
    protected QuestFacade questFacade;

    // several methods delegating lookups to the questFacade ...
}

有了这个部署和页面访问,我从GlassFish得到一个错误,QuestFacadeJNDI无法查找.

堆栈跟踪很长,但最初的原因可能就足够了:

Caused by: javax.naming.NamingException: Lookup failed for 'model.session.QuestFacade#model.session.QuestFacade' in SerialContext[myEnv={java.naming.factory.initial=com.sun.enterprise.naming.impl.SerialInitContextFactory, java.naming.factory.state=com.sun.corba.ee.impl.presentation.rmi.JNDIStateFactoryImpl, java.naming.factory.url.pkgs=com.sun.enterprise.naming} [Root exception is javax.naming.NameNotFoundException: model.session.QuestFacade#model.session.QuestFacade not found]
    at com.sun.enterprise.naming.impl.SerialContext.lookup(SerialContext.java:518)
    at com.sun.enterprise.naming.impl.SerialContext.lookup(SerialContext.java:455)
    at javax.naming.InitialContext.lookup(InitialContext.java:392)
    at javax.naming.InitialContext.lookup(InitialContext.java:392)
    at com.sun.ejb.EjbNamingReferenceManagerImpl.resolveEjbReference(EjbNamingReferenceManagerImpl.java:173)
    ... 74 more
Caused by: javax.naming.NameNotFoundException: model.session.QuestFacade#model.session.QuestFacade not found
    at com.sun.enterprise.naming.impl.TransientContext.doLookup(TransientContext.java:248)
    at com.sun.enterprise.naming.impl.TransientContext.lookup(TransientContext.java:215)
    at com.sun.enterprise.naming.impl.SerialContextProviderImpl.lookup(SerialContextProviderImpl.java:77)
    at com.sun.enterprise.naming.impl.LocalSerialContextProviderImpl.lookup(LocalSerialContextProviderImpl.java:119)
    at com.sun.enterprise.naming.impl.SerialContext.lookup(SerialContext.java:505)
    ... 78 more

我知道我正在说服GlassFish从同一个应用程序中的不同模块注入EJB.应该使用@Remote接口吗？我也尝试明确指定两者@Stateless和@EJB注释的名称,但没有任何成功.

我相信我做的事情基本上是错误的,但我找不到什么.

任何建议或将不胜感激!

Answer 1

我相信我做的事情基本上是错误的,但我找不到什么.

你在做什么错的是,如果你实现一个业务接口(无论是@Local或@Remote),那么您必须声明,其中注射发生具有不实际的bean类接口的类型,变量.

所以在你的情况下:

@Named
@SessionScoped
public class QuestBean implements Serializable {

    @EJB
    protected QuestFacadeLocal questFacade;

    // several methods delegating lookups to the questFacade ...
}

但是,当您进行本地(in-jvm)通信时,EJB中不需要业务接口.正如您所发现的,如果您没有为EJB指定业务接口,则可以注入bean类本身.这是因为你然后自动得到所谓的no-interface view.

如果需要,您可以选择声明您希望BOTH本地视图和无接口视图.这样,无论是声明bean类型本身还是业务接口,都可以在bean中注入bean类.为此,你使用@LocalBean.

@Stateless
@LocalBean
public class QuestFacade extends AbstractFacade<Quest> implements QuestFacadeLocal {
    // some methods here as well as EntityManager injection ...
}

因此,注射现在可以通过两种方式发生:

@Named
@SessionScoped
public class QuestBean implements Serializable {

    @EJB
    protected QuestFacadeLocal questFacade; // possible because of local view
    @EJB
    protected QuestFacade questFacadeN; // possible because of no-interface view

    // several methods delegating lookups to the questFacade ...
}

实际上,我并没有找到同时使用这两种方法的多少用途,但这可能会增加您的理解.