Question

请不要将其作为副本关闭，并引用我的通用NullPointerException答案。我知道NullPointerException是什么。这可能是EclipseLink错误或滥用其框架。

我们使用entityManager.createQuery() api运行一些查询，收到一个SQL字符串（我知道这种做法不好。我们最终会切换到命名查询）每隔一段时间（不常见）我们就会在NullPointerException得到这个奇怪的ReportItem.getDescriptor（参见下面的整个堆栈跟踪）。

两个奇怪的事情：一个是没有添加行号，第二个，此方法不能抛出NullPointerException - 该方法只返回this.descriptor。我们认为可能堆栈已损坏且实际异常从ExpressionQueryMechanism:710抛出，因此我尝试在710上使用调试器停止，使描述符为空。在这种情况下，我获得了预期的堆栈跟踪，在710上失败而在ReportItem.getDescriptor上没有。

有没有人遇到过这个？或者也许任何有用的想法可能是什么问题？我们使用的是EL 2.6.0-M3和JVM：IBM J9 VM（build 2.6，JRE 1.7.0 Linux x86-32 20151019_272770

堆栈跟踪：

Query: ReportQuery(******)
        at org.eclipse.persistence.exceptions.QueryException.prepareFailed(QueryException.java:1596)
        at org.eclipse.persistence.queries.DatabaseQuery.checkPrepare(DatabaseQuery.java:680)
        at org.eclipse.persistence.queries.ObjectLevelReadQuery.checkPrepare(ObjectLevelReadQuery.java:909)
        at org.eclipse.persistence.queries.DatabaseQuery.checkPrepare(DatabaseQuery.java:613)
        at org.eclipse.persistence.queries.DatabaseQuery.execute(DatabaseQuery.java:867)
        at org.eclipse.persistence.queries.ObjectLevelReadQuery.execute(ObjectLevelReadQuery.java:1133)
        at org.eclipse.persistence.queries.ReadAllQuery.execute(ReadAllQuery.java:403)
        at org.eclipse.persistence.internal.sessions.AbstractSession.internalExecuteQuery(AbstractSession.java:3212)
        at org.eclipse.persistence.internal.sessions.AbstractSession.executeQuery(AbstractSession.java:1802)
        at org.eclipse.persistence.internal.sessions.AbstractSession.executeQuery(AbstractSession.java:1784)
        at org.eclipse.persistence.queries.ObjectLevelReadQuery.executeInUnitOfWork(ObjectLevelReadQuery.java:1219)
        at org.eclipse.persistence.internal.sessions.UnitOfWorkImpl.internalExecuteQuery(UnitOfWorkImpl.java:2896)
        at org.eclipse.persistence.internal.sessions.AbstractSession.executeQuery(AbstractSession.java:1802)
        at org.eclipse.persistence.internal.sessions.AbstractSession.executeQuery(AbstractSession.java:1784)
        at org.eclipse.persistence.internal.sessions.AbstractSession.executeQuery(AbstractSession.java:1749)
        at org.eclipse.persistence.internal.jpa.QueryImpl.executeReadQuery(QueryImpl.java:258)
        at org.eclipse.persistence.internal.jpa.QueryImpl.getResultList(QueryImpl.java:469)
        ... 101 more
Caused by: java.lang.NullPointerException
        at org.eclipse.persistence.internal.queries.ReportItem.getDescriptor(ReportItem.java)
        at org.eclipse.persistence.internal.queries.ExpressionQueryMechanism.extractStatementFromItem(ExpressionQueryMechanism.java:710)
        at org.eclipse.persistence.internal.queries.ExpressionQueryMechanism.buildReportQuerySelectStatement(ExpressionQueryMechanism.java:630)
        at org.eclipse.persistence.internal.queries.ExpressionQueryMechanism.buildReportQuerySelectStatement(ExpressionQueryMechanism.java:586)
        at org.eclipse.persistence.internal.queries.ExpressionQueryMechanism.prepareReportQuerySelectAllRows(ExpressionQueryMechanism.java:1695)
       at org.eclipse.persistence.queries.ReportQuery.prepareSelectAllRows(ReportQuery.java:1203)
        at org.eclipse.persistence.queries.ReadAllQuery.prepare(ReadAllQuery.java:751)
        at org.eclipse.persistence.queries.ReportQuery.prepare(ReportQuery.java:1071)
        at org.eclipse.persistence.queries.DatabaseQuery.checkPrepare(DatabaseQuery.java:661)
        ... 116 more

执行DatabaseQuery（ReportQuery）时的EclipseLink异常

0 个答案: