从无状态EJB访问SessionScoped对象

Question

我有一个SessionScoped类.对于每个用户访问,我需要一个自己的这个类的实例.一切都很好,很长一段时间.但是现在我还需要从后端访问这些对象,而无需任何用户交互.我确实有一个无状态的企业bean,但每当我想访问会话作用域对象时,我都会得到一个例外.一个简单的示例代码如下:

@SessionScoped
public class SessionObj implements Serializable {

    public String getValue() {
        return "Hello World";
    }
}

@Stateless
public class StatelessBean {

    private static final Logger LOG=Logger.getLogger(StatelessBean.class);

    @Inject
    private SessionObj sessionObj;

    public void test() {
        LOG.info("session object: "+sessionObj);
        LOG.info("Method call: "+sessionObj.getValue());
    }

}

但调用测试方法的结果如下:

12:19:10,484 ERROR [org.jboss.as.ejb3.tx.CMTTxInterceptor] (EJB default - 6)    javax.ejb.EJBTransactionRolledbackException: WELD-001303 No active contexts for scope type javax.enterprise.context.SessionScoped
12:19:10,484 ERROR [org.jboss.ejb3.invocation] (EJB default - 6) JBAS014134: EJB Invocation failed on component StatelessBean for method public void package.StatelessBean.test(): javax.ejb.EJBTransactionRolledbackException: WELD-001303 No active contexts for scope type javax.enterprise.context.SessionScoped
    at org.jboss.as.ejb3.tx.CMTTxInterceptor.handleInCallerTx(CMTTxInterceptor.java:139) [jboss-as-ejb3-7.1.1.Final.jar:7.1.1.Final]
    at org.jboss.as.ejb3.tx.CMTTxInterceptor.invokeInCallerTx(CMTTxInterceptor.java:204) [jboss-as-ejb3-7.1.1.Final.jar:7.1.1.Final]
    at org.jboss.as.ejb3.tx.CMTTxInterceptor.required(CMTTxInterceptor.java:306) [jboss-as-ejb3-7.1.1.Final.jar:7.1.1.Final]
    at org.jboss.as.ejb3.tx.CMTTxInterceptor.processInvocation(CMTTxInterceptor.java:190) [jboss-as-ejb3-7.1.1.Final.jar:7.1.1.Final]
    at org.jboss.invocation.InterceptorContext.proceed(InterceptorContext.java:288) [jboss-invocation-1.1.1.Final.jar:1.1.1.Final]
    ...
Caused by: org.jboss.weld.context.ContextNotActiveException: WELD-001303 No active    contexts for scope type javax.enterprise.context.SessionScoped
    at org.jboss.weld.manager.BeanManagerImpl.getContext(BeanManagerImpl.java:598) [weld-core-1.1.5.AS71.Final.jar:2012-02-10 15:31]
    at org.jboss.weld.bean.proxy.ContextBeanInstance.getInstance(ContextBeanInstance.java:71) [weld-core-1.1.5.AS71.Final.jar:2012-02-10 15:31]
    at org.jboss.weld.bean.proxy.ProxyMethodHandler.invoke(ProxyMethodHandler.java:79) [weld-core-1.1.5.AS71.Final.jar:2012-02-10 15:31]
    at package.SessionObj$Proxy$_$$_WeldClientProxy.toString(SessionObj$Proxy$_$$_WeldClientProxy.java) [ws_core_job_manager.jar:]
    at java.lang.String.valueOf(String.java:2826) [rt.jar:1.6.0_21]
    at java.lang.StringBuilder.append(StringBuilder.java:115) [rt.jar:1.6.0_21]
    at package.StatelessBean.test(StatelessBean.java:29) [ws_core_job_manager.jar:]
    ...

所以我的问题是:*是否有任何选项可以访问对象,即使没有任何技巧的会话？*有没有选择从我的无状态类中生成一个会话？

我理解异常的原因但我希望为现有代码的这种新用法设置一个"全局"会话.当然,实际上并不是那么容易,并且将会话范围代码更改为POJO并且会话范围容器并不那么容易.

环境:

• JDK 1.6
• JBOSS 7.1.1

解:

如Jan所述:将StatelessBean扩展如下:

@Stateless
public class StatelessBean {

    private static final Logger LOG=Logger.getLogger(StatelessBean.class);

    @Inject
    private BoundSessionContext sessionContext;

    @Inject
    private SessionObj sessionObj;

    public void test() {
        Map<String,Object> myMap=new HashMap<String,Object>();
        sessionContext.associate(myMap);
        sessionContext.activate();

        LOG.info("session object: "+sessionObj);
        LOG.info("Method call: "+sessionObj.getValue());

        sessionContext.invalidate();
        sessionContext.deactivate();
    }

}

这个例子正在发挥作用!现在我只需了解细节;-)

Answer 1

问题不是访问会话范围的bean本身,问题是会话不活动,可能是因为它从未启动过(例如EJB远程处理).

你可以做的是BoundSessionContext手动启动,看看这里.我这样做是为了对话,而且效果很好.