無法使用JPA將null持久化到oracle BLOB中

Question

我正在嘗試使用JPA將圖像Byte[]和調度程序TimerHandle到oracle 11g數據庫（EclipseLink 2.3.x）

當該屬性的值不為null時，JPA可以將Byte [] / TimerHandle持久化到數據庫，但是當這些屬性為null ，它將給出此異常。

Caused by: java.lang.ClassCastException: oracle.sql.BLOB incompatible with oracle.sql.BLOB
    at oracle.jdbc.driver.OraclePreparedStatement.setBlob(OraclePreparedStatement.java:6663)
    at oracle.jdbc.driver.OraclePreparedStatementWrapper.setBlob(OraclePreparedStatementWrapper.java:128)
    at org.apache.openjpa.lib.jdbc.DelegatingPreparedStatement.setBlob(DelegatingPreparedStatement.java:387)
    at org.apache.openjpa.lib.jdbc.LoggingConnectionDecorator$LoggingConnection$LoggingPreparedStatement.setBlob(LoggingConnectionDecorator.java:1499)
    at org.apache.openjpa.lib.jdbc.DelegatingPreparedStatement.setBlob(DelegatingPreparedStatement.java:387)
    at org.apache.openjpa.jdbc.sql.OracleDictionary.setNull(OracleDictionary.java:633)
    at org.apache.openjpa.jdbc.sql.DBDictionary.setTyped(DBDictionary.java:1285)
    at org.apache.openjpa.jdbc.sql.RowImpl.flush(RowImpl.java:896)
    at org.apache.openjpa.jdbc.sql.RowImpl.flush(RowImpl.java:856)
    at org.apache.openjpa.jdbc.kernel.PreparedStatementManagerImpl.flushAndUpdate(PreparedStatementManagerImpl.java:117)
    at org.apache.openjpa.jdbc.kernel.BatchingPreparedStatementManagerImpl.batchOrExecuteRow(BatchingPreparedStatementManagerImpl.java:99)
    at org.apache.openjpa.jdbc.kernel.BatchingPreparedStatementManagerImpl.flushAndUpdate(BatchingPreparedStatementManagerImpl.java:83)
    at com.ibm.ws.persistence.jdbc.kernel.PreparedStatementManagerImpl.flushAndUpdate(PreparedStatementManagerImpl.java:63)
    at org.apache.openjpa.jdbc.kernel.PreparedStatementManagerImpl.flushInternal(PreparedStatementManagerImpl.java:100)
    at org.apache.openjpa.jdbc.kernel.PreparedStatementManagerImpl.flush(PreparedStatementManagerImpl.java:88)
    at org.apache.openjpa.jdbc.kernel.ConstraintUpdateManager.flush(ConstraintUpdateManager.java:550)
    at org.apache.openjpa.jdbc.kernel.ConstraintUpdateManager.flush(ConstraintUpdateManager.java:106)
    at org.apache.openjpa.jdbc.kernel.BatchingConstraintUpdateManager.flush(BatchingConstraintUpdateManager.java:59)
    at org.apache.openjpa.jdbc.kernel.AbstractUpdateManager.flush(AbstractUpdateManager.java:105)
    at org.apache.openjpa.jdbc.kernel.AbstractUpdateManager.flush(AbstractUpdateManager.java:78)
    at org.apache.openjpa.jdbc.kernel.JDBCStoreManager.flush(JDBCStoreManager.java:737)
    at org.apache.openjpa.kernel.DelegatingStoreManager.flush(DelegatingStoreManager.java:131)
    at org.apache.openjpa.kernel.BrokerImpl.flush(BrokerImpl.java:2178)
    at org.apache.openjpa.kernel.BrokerImpl.flushSafe(BrokerImpl.java:2076)
    at org.apache.openjpa.kernel.BrokerImpl.flush(BrokerImpl.java:1847)
    ... 70 more

如何解決此問題，以便null可以在數據庫中作為（null）持久化到數據庫？

Answer 1

我找到了部分解決方案...有此問題時，請使用純oracle.sql.BLOB而不是映射到BLOB的任何其他類。

@Entity
public class FileStorage implements Serializable {
    @Id
    private Long fileId;
    @Lob
    //private byte[] fileData; replaced this line with the line below.
    private oracle.sql.BLOB fileData;
    //Getter and setter
}

public class WorkingClass{
    private EntityManager em;
    public foo(){
        FileStorage f = new FileStorage();
        f.setFileData(BLOB.getEmptyBLOB());
        //f.getFileData().setBytes(someByteArrayData);
        em.persist(f);
    }
}

public class ErrorClass{
    private EntityManager em;
    public foo(){
        FileStorage f = new FileStorage();
        f.setFileData();
        //fail when the line below is commented
        //f.setFileData(someByteArrayData);
        em.persist(f);
    }
}

但是現在問題困擾着TimerHandle 。 在使用ObjectOutputStream / ObjectInputStream進行手動序列化和反序列化之后，計時器似乎未正確序列化，導致當我調用((TimerHandle) o).getTimer()時導致NoSuchObjectLocalException ，甚至我確認計時器仍在運行（調用一個@Timeout方法，該方法不斷輸出一個消息）。