Question

我已经定义了一个会话bean基类。此类是抽象的，包含受保护的最终方法。会话实现类扩展了抽象类并定义了其他方法。在部署期间，Glassfish 3.1.2服务器会生成一个异常，说明该方法被覆盖。

abstract class AbstractSessionBean {
    @PersistenceContext(unitName="primary")
    private EntityManager em;

    protected final EntityManager getEntityManager() {
       return em;
    }
}

@Startup
@Stateless
class RegistrationSessionBean extends AbstractSessionBean {
     public void loadRegistration() {
        ...
     }
}

在部署期间，glassfish服务器会抛出异常。如果我将AbstractSessionBean的方法设为非final，则部署成功。

这是否意味着会话bean不能拥有最终方法？或者此行为仅适用于Glassfish 3.1.2。

异常消息是：

[#|2013-08-26T17:45:48.542+0530|SEVERE|glassfish3.1.2|javax.enterprise.system.tools.admin.org.glassfish.deployment.admin|_ThreadID=47;_ThreadName=Thread-2;|Exception while loading the app : EJB Container initialization error
java.lang.RuntimeException: Could not invoke defineClass!
    at com.sun.ejb.containers.EjbOptionalIntfGenerator.makeClass(EjbOptionalIntfGenerator.java:448)
    at com.sun.ejb.containers.EjbOptionalIntfGenerator.access$200(EjbOptionalIntfGenerator.java:64)
    at com.sun.ejb.containers.EjbOptionalIntfGenerator$1.run(EjbOptionalIntfGenerator.java:99)
    at java.security.AccessController.doPrivileged(Native Method)
    at com.sun.ejb.containers.EjbOptionalIntfGenerator.loadClass(EjbOptionalIntfGenerator.java:96)
    at com.sun.ejb.containers.BaseContainer.instantiateOptionalEJBLocalBusinessObjectImpl(BaseContainer.java:3886)
    at com.sun.ejb.containers.StatelessSessionContainer.initializeHome(StatelessSessionContainer.java:253)
    at com.sun.ejb.containers.ContainerFactoryImpl.createContainer(ContainerFactoryImpl.java:167)
    at org.glassfish.ejb.startup.EjbApplication.loadContainers(EjbApplication.java:230)
    at org.glassfish.ejb.startup.EjbDeployer.load(EjbDeployer.java:305)
    at org.glassfish.ejb.startup.EjbDeployer.load(EjbDeployer.java:108)
    at org.glassfish.internal.data.ModuleInfo.load(ModuleInfo.java:186)
    at org.glassfish.internal.data.ApplicationInfo.load(ApplicationInfo.java:264)
    at com.sun.enterprise.v3.server.ApplicationLifecycle.deploy(ApplicationLifecycle.java:460)
    at com.sun.enterprise.v3.server.ApplicationLifecycle.deploy(ApplicationLifecycle.java:240)
    at org.glassfish.deployment.admin.DeployCommand.execute(DeployCommand.java:389)
    at com.sun.enterprise.v3.admin.CommandRunnerImpl$1.execute(CommandRunnerImpl.java:348)
    at com.sun.enterprise.v3.admin.CommandRunnerImpl.doCommand(CommandRunnerImpl.java:363)
    at com.sun.enterprise.v3.admin.CommandRunnerImpl.doCommand(CommandRunnerImpl.java:1085)
    at com.sun.enterprise.v3.admin.CommandRunnerImpl.access$1200(CommandRunnerImpl.java:95)
    at com.sun.enterprise.v3.admin.CommandRunnerImpl$ExecutionContext.execute(CommandRunnerImpl.java:1291)
    at com.sun.enterprise.v3.admin.CommandRunnerImpl$ExecutionContext.execute(CommandRunnerImpl.java:1259)
    at com.sun.enterprise.v3.admin.AdminAdapter.doCommand(AdminAdapter.java:461)
    at com.sun.enterprise.v3.admin.AdminAdapter.service(AdminAdapter.java:212)
    at com.sun.grizzly.tcp.http11.GrizzlyAdapter.service(GrizzlyAdapter.java:179)
    at com.sun.enterprise.v3.server.HK2Dispatcher.dispath(HK2Dispatcher.java:117)
    at com.sun.enterprise.v3.services.impl.ContainerMapper$Hk2DispatcherCallable.call(ContainerMapper.java:354)
    at com.sun.enterprise.v3.services.impl.ContainerMapper.service(ContainerMapper.java:195)
    at com.sun.grizzly.http.ProcessorTask.invokeAdapter(ProcessorTask.java:860)
    at com.sun.grizzly.http.ProcessorTask.doProcess(ProcessorTask.java:757)
    at com.sun.grizzly.http.ProcessorTask.process(ProcessorTask.java:1056)
    at com.sun.grizzly.http.DefaultProtocolFilter.execute(DefaultProtocolFilter.java:229)
    at com.sun.grizzly.DefaultProtocolChain.executeProtocolFilter(DefaultProtocolChain.java:137)
    at com.sun.grizzly.DefaultProtocolChain.execute(DefaultProtocolChain.java:104)
    at com.sun.grizzly.DefaultProtocolChain.execute(DefaultProtocolChain.java:90)
    at com.sun.grizzly.http.HttpProtocolChain.execute(HttpProtocolChain.java:79)
    at com.sun.grizzly.ProtocolChainContextTask.doCall(ProtocolChainContextTask.java:54)
    at com.sun.grizzly.SelectionKeyContextTask.call(SelectionKeyContextTask.java:59)
    at com.sun.grizzly.ContextTask.run(ContextTask.java:71)
    at com.sun.grizzly.util.AbstractThreadPool$Worker.doWork(AbstractThreadPool.java:532)
    at com.sun.grizzly.util.AbstractThreadPool$Worker.run(AbstractThreadPool.java:513)
    at java.lang.Thread.run(Thread.java:724)
Caused by: java.lang.reflect.InvocationTargetException
    at sun.reflect.GeneratedMethodAccessor50.invoke(Unknown Source)
    at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
    at java.lang.reflect.Method.invoke(Method.java:606)
    at com.sun.ejb.containers.EjbOptionalIntfGenerator.makeClass(EjbOptionalIntfGenerator.java:445)
    ... 41 more
Caused by: java.lang.VerifyError: class org.bean.test.persistence.util.__EJB31_Generated__RegistrationSessionBean__Intf____Bean__ overrides final method getContext.()Ljavax/ejb/SessionContext;
    at java.lang.ClassLoader.defineClass1(Native Method)
    at java.lang.ClassLoader.defineClass(ClassLoader.java:792)
    ... 45 more
|#]

Answer 1

简短的回答是“是”，但是长的答案是“一般是肯定的，但是在使用无界面视图时没有”。无接口视图的限制来自EJB 3.2规范的第3.4.4节：

只有bean类的公共方法和除了的任何超类可以通过无接口视图调用java.lang.Object。尝试通过任何其他访问修饰符调用方法无界面视图引用必须导致 javax.ejb.EJBException异常。

生成无接口视图代理时，EJB容器必须创建EJB类的子类，并覆盖所有公共方法以提供代理行为。但是，上面的规范引用中的第二句意味着还必须重写所有剩余的非私有方法，以便抛出无条件的EJBException。也就是说，来自应用程序服务器的错误消息可能更好。

无状态会话bean可以保护最终方法吗？

1 个答案: