【发布时间】：2009-12-28 02:43:54
【问题描述】：
我被难住了。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带有 @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)
【问题讨论】：
标签： mysql hibernate drools drools-flow