EJB3 - 将一个 MDB 注入另一个 MDB？答案

【问题标题】：EJB3 - Inject a MDB into another MDB?EJB3 - 将一个 MDB 注入另一个 MDB？
【发布时间】：2011-11-23 18:03:23
【问题描述】：

由于消息驱动 bean 是一种 EJB，我希望我能够将一个注入另一个，但我遇到了问题。我必须向 MDB 注入一个类似这样的东西：

@MessageDriven(mappedName = "jms/QueueOne")
public class MessageBeanOne
{
    @EJB
    private EntityService service;

    @EJB
    private MessageBeanTwo mdbTwo;

    public void onMessage(Message message)
    {
        log.info("Received message from jms/QueueOne: " + message);
        String entityId= null;

        try
        {
            if (message instanceof TextMessage)
            {
                entityId = ((TextMessage) message).getText();
            }
            else
            {
                // error handling
            }
        }
        catch (Exception ex)
        {
           // error handling
        }

        Entity myEntity = service.getEntity(entityId);
        mdbTwo.process(myEntity);
    }
}


@MessageDriven(mappedName = "jms/TopicOne")
public class MessageBeanTwo
{
    @EJB
    private EntityService service;

    private boolean goodToProcess = true;

    public void process(Entity entity)
    {
        while(goodToProcess)
        {
            // process entity using injected service object
        }
    }

    public void onMessage(Message message)
    {
        log.info("Received message from jms/TopicOne: " + message);
        String status = null;

        try
        {
            if (message instanceof TextMessage)
            {
                status = ((TextMessage) message).getText();
            }
            else
            {
                // error handling
            }
        }
        catch (Exception ex)
        {
           // error handling
        }

        if (status.equals("cancel")
        {
            goodToProcess = false;
        }
    }
}

它们被部署为 Glassfish 3.1.1 中的耳朵。我在 server.log 中收到此错误消息：

[#|2011-11-23T10:55:35.546-0700|SEVERE|glassfish3.1.1|javax.enterprise.system.container.ejb.mdb.com.sun.ejb.containers|_ThreadID=19;_ThreadName=Thread-2;|MDB00050: Message-driven bean [MyApp-ear-1.0:MessageBeanOne]: Exception in creating message-driven ejb : [com.sun.enterprise.container.common.spi.util.InjectionException: Exception attempting to inject Remote ejb-ref name=my.package.MessageBeanOne/messageBeanTwo,Remote 3.x interface =my.package.MessageBeanTwo,ejb-link=null,lookup=,mappedName=,jndi-name=my.package.MessageBeanTwo,refType=Session into class my.package.MessageBeanOne: Lookup failed for 'java:comp/env/my.package.MessageBeanOne/messageBeanTwo' 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}]|#]
[#|2011-11-23T10:55:35.547-0700|SEVERE|glassfish3.1.1|javax.enterprise.system.container.ejb.mdb.com.sun.ejb.containers|_ThreadID=19;_ThreadName=Thread-2;|com.sun.enterprise.container.common.spi.util.InjectionException com.sun.enterprise.container.common.spi.util.InjectionException: Exception attempting to inject Remote ejb-ref name=my.package.MessageBeanOne/messageBeanTwo,Remote 3.x interface =my.package.MessageBeanTwo,ejb-link=null,lookup=,mappedName=,jndi-name=my.package.MessageBeanTwo,refType=Session into class my.package.MessageBeanOne: Lookup failed for 'java:comp/env/my.package.MessageBeanOne/messageBeanTwo' 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}
        at com.sun.enterprise.container.common.impl.util.InjectionManagerImpl._inject(InjectionManagerImpl.java:703)
        at com.sun.enterprise.container.common.impl.util.InjectionManagerImpl.inject(InjectionManagerImpl.java:470)
        at com.sun.enterprise.container.common.impl.util.InjectionManagerImpl.injectInstance(InjectionManagerImpl.java:171)
        at com.sun.ejb.containers.BaseContainer.injectEjbInstance(BaseContainer.java:1691)
        at com.sun.ejb.containers.MessageBeanContainer.createMessageDrivenEJB(MessageBeanContainer.java:706)
        at com.sun.ejb.containers.MessageBeanContainer.access$100(MessageBeanContainer.java:101)
        at com.sun.ejb.containers.MessageBeanContainer$MessageBeanContextFactory.create(MessageBeanContainer.java:483)
        at com.sun.ejb.containers.util.pool.NonBlockingPool.getObject(NonBlockingPool.java:247)
        at com.sun.ejb.containers.MessageBeanContainer._getContext(MessageBeanContainer.java:547)
        at com.sun.ejb.containers.BaseContainer.getContext(BaseContainer.java:2528)
        at com.sun.ejb.containers.MessageBeanContainer.beforeMessageDelivery(MessageBeanContainer.java:989)
        at com.sun.ejb.containers.MessageBeanListenerImpl.beforeMessageDelivery(MessageBeanListenerImpl.java:77)
        at com.sun.enterprise.connectors.inbound.MessageEndpointInvocationHandler.invoke(MessageEndpointInvocationHandler.java:139)
        at $Proxy337.beforeDelivery(Unknown Source)
        at com.sun.messaging.jms.ra.OnMessageRunner.run(OnMessageRunner.java:247)
        at com.sun.enterprise.connectors.work.OneWork.doWork(OneWork.java:114)
        at com.sun.corba.ee.impl.orbutil.threadpool.ThreadPoolImpl$WorkerThread.performWork(ThreadPoolImpl.java:497)
        at com.sun.corba.ee.impl.orbutil.threadpool.ThreadPoolImpl$WorkerThread.run(ThreadPoolImpl.java:540)
Caused by: javax.naming.NamingException: Lookup failed for 'java:comp/env/my.package.MessageBeanOne/messageBeanTwo' 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.NamingException: Exception resolving Ejb for 'Remote ejb-ref name=my.package.MessageBeanOne/messageBeanTwo,Remote 3.x interface =my.package.MessageBeanTwo,ejb-link=null,lookup=,mappedName=,jndi-name=my.package.MessageBeanTwo,refType=Session' .  Actual (possibly internal) Remote JNDI name used for lookup is 'my.package.MessageBeanTwo#my.package.MessageBeanTwo' [Root exception is javax.naming.NamingException: Lookup failed for 'my.package.MessageBeanTwo#my.package.MessageBeanTwo' 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: my.package.MessageBeanTwo#my.package.MessageBeanTwo 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.enterprise.container.common.impl.util.InjectionManagerImpl._inject(InjectionManagerImpl.java:599)
        ... 17 more
Caused by: javax.naming.NamingException: Exception resolving Ejb for 'Remote ejb-ref name=my.package.MessageBeanOne/messageBeanTwo,Remote 3.x interface =my.package.MessageBeanTwo,ejb-link=null,lookup=,mappedName=,jndi-name=my.package.MessageBeanTwo,refType=Session' .  Actual (possibly internal) Remote JNDI name used for lookup is 'my.package.MessageBeanTwo#my.package.MessageBeanTwo' [Root exception is javax.naming.NamingException: Lookup failed for 'my.package.MessageBeanTwo#my.package.MessageBeanTwo' 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: my.package.MessageBeanTwo#my.package.MessageBeanTwo not found]]
        at com.sun.ejb.EjbNamingReferenceManagerImpl.resolveEjbReference(EjbNamingReferenceManagerImpl.java:178)
        at com.sun.enterprise.container.common.impl.ComponentEnvManagerImpl$EjbReferenceProxy.create(ComponentEnvManagerImpl.java:1106)
        at com.sun.enterprise.naming.impl.GlassfishNamingManagerImpl.lookup(GlassfishNamingManagerImpl.java:776)
        at com.sun.enterprise.naming.impl.GlassfishNamingManagerImpl.lookup(GlassfishNamingManagerImpl.java:744)
        at com.sun.enterprise.naming.impl.JavaURLContext.lookup(JavaURLContext.java:172)
        at com.sun.enterprise.naming.impl.SerialContext.lookup(SerialContext.java:498)
        ... 21 more
Caused by: javax.naming.NamingException: Lookup failed for 'my.package.MessageBeanTwo#my.package.MessageBeanTwo' 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: my.package.MessageBeanTwo#my.package.MessageBeanTwo 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)
        ... 26 more
Caused by: javax.naming.NameNotFoundException: my.package.MessageBeanTwo#my.package.MessageBeanTwo 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)
        ... 30 more
|#]

[#|2011-11-23T10:55:35.548-0700|WARNING|glassfish3.1.1|javax.resourceadapter.mqjmsra.inbound.message|_ThreadID=19;_ThreadName=Thread-2;|MQJMSRA_MR2001: run:Caught Exception from onMessage():Redelivering:
javax.ejb.EJBException: ESwimMessageBeanTwo-ear-1.0:MessageBeanOne: message-driven bean invocation closed by container
        at com.sun.ejb.containers.MessageBeanContainer.deliverMessage(MessageBeanContainer.java:1163)
        at com.sun.ejb.containers.MessageBeanListenerImpl.deliverMessage(MessageBeanListenerImpl.java:81)
        at com.sun.enterprise.connectors.inbound.MessageEndpointInvocationHandler.invoke(MessageEndpointInvocationHandler.java:171)
        at $Proxy337.onMessage(Unknown Source)
        at com.sun.messaging.jms.ra.OnMessageRunner.run(OnMessageRunner.java:260)
        at com.sun.enterprise.connectors.work.OneWork.doWork(OneWork.java:114)
        at com.sun.corba.ee.impl.orbutil.threadpool.ThreadPoolImpl$WorkerThread.performWork(ThreadPoolImpl.java:497)
        at com.sun.corba.ee.impl.orbutil.threadpool.ThreadPoolImpl$WorkerThread.run(ThreadPoolImpl.java:540)
|#]

在尝试搜索这是否真的可行时，我遇到了很多关于将 MDB 注入会话 bean，但从未将 MDB 注入另一个 MDB 的参考。也许这不可行？

【问题讨论】：

它们是“消息驱动的”bean，你为什么要尝试将一个注入另一个。您是否尝试自己调用onMessage() 方法？
MessageBeanTwo 有一个 MessageBeanOne 调用的 process() 方法。他没有调用 onMessage() 而是调用了这个 process() 方法。
最初，MessageBeanOne 创建了一个 MessageBeanTwo 的新实例来进行处理，但由于它没有被注入（因此不是容器管理），所以出现了问题。
我编辑了示例以显示 MessageBeanTwo 还使用了注入的 EntityService 对象。如果 MessageBeanOne 通过“new”获得了 MessageBeanTwo 的实例，则 EntityService 为空。因此需要将 MessageBeanTwo 注入到 MessageBeanOne 中。希望澄清。

标签： java jakarta-ee ejb-3.1

【解决方案1】：

可能与问题没有直接关系，但我会将process() 方法提取到两个MDB 都可以修改的自己的类中。这样，MDB 就有了处理传入消息的sole responsibility，而第三个新类执行“实体处理”。然后这个类可能是您在两个 MDB 中注入的另一个 EJB。

在我看来，MDB 通常应该只专门用于处理接收消息。

编辑

通过再次查看您的代码，我鼓励您三思而后行。您的 MDB 具有状态，考虑到容器创建实例池，这可能会导致意外结果。您可能处于MessageBeanTwo 的实例与goodToProcess = false 合并的情况。如果从池中取出该实例并注入MessageBeanOne 并调用process() 方法，则可能会得到错误的结果。

这一切都假设您可以将 MDB 注入另一个 MDB，这是我从未做过或听说过的。

【讨论】：

是的，我同意，我会将实际处理工作交给另一个 Session bean。
我喜欢将 MDB2 分离为一个 MDB 和一个（有状态的）会话 bean 的想法。但是，如果 Session bean 被注入到两个 MDB 中，我如何确保它是同一个？
更正，应该是 Statelss Session bean。
我实际上担心在两个 MDB 之间创建依赖关系的整个想法，甚至在主题和它们从中消费的队列之间创建依赖关系。你能给出你想要达到的目标的功能描述吗？
该应用程序是一个批处理器。批次通过部署为单独的 web 应用程序的 servlet 上传。它进行文件验证，保存到数据库并将消息发送到批量接收队列。上面的 MDB1 监听这些消息，从数据库中检索批处理信息，创建一个处理器并开始处理。处理器是 MDB2。最初，它创建了一个“新的”MDB2，但导致了上述问题。 MDB2 是 MDB 的原因是它侦听另一个队列上的消息，指示应该暂停/恢复/取消特定批次的处理。