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我难住了。我正在尝试使用 Drools-flow 实现持久性，并且我想获取工作项/流程实例上的属性值，但是每次我尝试获取工作项或流程实例时，我都会得到下面的堆栈跟踪。

我正在浏览源代码，据我所知，每当我尝试在实体类中获取一个用@Lob 注释的属性时，都会发生这种情况。

我的环境是使用 BTM 作为事务管理器的 hibernate/mysql/JPA 持久性。

我调用 getProcessInstance 如下：


ksession = JPAKnowledgeService.loadStatefulKnowledgeSession(ksession.getId(), m_kbase, null, m_environment);         
m_pi = ksession.getProcessInstance(m_pi.getId());

我究竟做错了什么？


java.lang.NullPointerException
    at java.io.ByteArrayInputStream.(ByteArrayInputStream.java:89)
    at org.drools.persistence.processinstance.ProcessInstanceInfo.getProcessInstance(ProcessInstanceInfo.java:135)
    at org.drools.persistence.processinstance.JPAProcessInstanceManager.getProcessInstance(JPAProcessInstanceManager.java:62)
    at org.drools.common.AbstractWorkingMemory.getProcessInstance(AbstractWorkingMemory.java:1793)
    at org.drools.impl.StatefulKnowledgeSessionImpl.getProcessInstance(StatefulKnowledgeSessionImpl.java:261)Hibernate: select      at org.drools.command.runtime.process.GetProcessInstanceCommand.execute(GetProcessInstanceCommand.java:29)
    at org.drools.command.runtime.process.GetProcessInstanceCommand.execute(GetProcessInstanceCommand.java:12)
    at org.drools.persistence.session.SingleSessionCommandService.execute(SingleSessionCommandService.java:254)
    at org.drools.command.impl.CommandBasedStatefulKnowledgeSession.getProcessInstance(CommandBasedStatefulKnowledgeSession.java:95)
    at com.thoughtvine.tracks.workflow.TracksFlow.getParameterFromWorkItem(TracksFlow.java:182)
    at com.thoughtvine.tracks.workflow.test.TestTracksFlow.testGetWorkItem(TestTracksFlow.java:118)
    at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
    at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:39)
    at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:25)
    at java.lang.reflect.Method.invoke(Method.java:597)
    at org.junit.runners.model.FrameworkMethod$1.runReflectiveCall(FrameworkMethod.java:44)
    at org.junit.internal.runners.model.ReflectiveCallable.run(ReflectiveCallable.java:15)
    at org.junit.runners.model.FrameworkMethod.invokeExplosively(FrameworkMethod.java:41)
    at org.junit.internal.runners.statements.InvokeMethod.evaluate(InvokeMethod.java:20)
    at org.junit.internal.runners.statements.RunBefores.evaluate(RunBefores.java:28)
    at org.junit.internal.runners.statements.RunAfters.evaluate(RunAfters.java:31)
    at org.junit.runners.BlockJUnit4ClassRunner.runChild(BlockJUnit4ClassRunner.java:73)
    at org.junit.runners.BlockJUnit4ClassRunner.runChild(BlockJUnit4ClassRunner.java:46)
    at org.junit.runners.ParentRunner.runChildren(ParentRunner.java:180)
    at org.junit.runners.ParentRunner.access$000(ParentRunner.java:41)
    at org.junit.runners.ParentRunner$1.evaluate(ParentRunner.java:173)
    at org.junit.internal.runners.statements.RunBefores.evaluate(RunBefores.java:28)
    at org.junit.internal.runners.statements.RunAfters.evaluate(RunAfters.java:31)
    at org.junit.runners.ParentRunner.run(ParentRunner.java:220)
    at org.eclipse.jdt.internal.junit4.runner.JUnit4TestReference.run(JUnit4TestReference.java:46)
    at org.eclipse.jdt.internal.junit.runner.TestExecution.run(TestExecution.java:38)
    at org.eclipse.jdt.internal.junit.runner.RemoteTestRunner.runTests(RemoteTestRunner.java:467)
    at org.eclipse.jdt.internal.junit.runner.RemoteTestRunner.runTests(RemoteTestRunner.java:683)
    at org.eclipse.jdt.internal.junit.runner.RemoteTestRunner.run(RemoteTestRunner.java:390)
    at org.eclipse.jdt.internal.junit.runner.RemoteTestRunner.main(RemoteTestRunner.java:197)
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1 回答 1

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我不是这些事情的专家......但通常 LOB 的处理方式完全不同，您的 LOB 的实际检索是否可能被推迟，因此您在尝试从中读取时得到一个空点（使用 ByteArrayInputStream）？

可能是 JPA 配置中的设置...正如我所说，这是理论上的可能性

于 2010-11-18T23:15:46.053 回答