我正在尝试使用 DBUnit 将我的数据库 HSQLDB 的全部内容导出到 XML，并且我遇到了我无法理解的空指针错误。我正在关注常见问题解答中的示例：
IDatabaseConnection xmlConnection = new DatabaseConnection(conn);
IDataSet allTables = xmlConnection.createDataSet();
XmlDataSet.write(allTables, new FileOutputStream(DATABASE_PATH + ".xml"));空指针错误发生在最后一行。conn 和 DATABASE_PATH 不为空，因为它们都经过检查并稍后在程序中使用而没有问题（使用 OpenCSV 将数据库导出为 CSV，它可以完美地完全按预期工作）。
堆栈跟踪如下：
org.dbunit.dataset.DataSetException: java.sql.SQLException: java.lang.NullPointerException java.lang.NullPointerException
at org.dbunit.database.DatabaseDataSet.initialize(DatabaseDataSet.java:243)
at org.dbunit.database.DatabaseDataSet.getTableNames(DatabaseDataSet.java:272)
at org.dbunit.database.DatabaseDataSet.createIterator(DatabaseDataSet.java:258)
at org.dbunit.dataset.AbstractDataSet.iterator(AbstractDataSet.java:189)
at org.dbunit.dataset.stream.DataSetProducerAdapter.(DataSetProducerAdapter.java:63)
at org.dbunit.dataset.xml.XmlDataSetWriter.write(XmlDataSetWriter.java:128)
at org.dbunit.dataset.xml.XmlDataSet.write(XmlDataSet.java:104)
at org.dbunit.dataset.xml.XmlDataSet.write(XmlDataSet.java:91)
at pms.DatabaseExporter.exportToXML(DatabaseExporter.java:181)
at pms.DatabaseExporter.main(DatabaseExporter.java:301)
Caused by: java.sql.SQLException: java.lang.NullPointerException java.lang.NullPointerException
at org.hsqldb.jdbc.Util.sqlException(Util.java:224)
at org.hsqldb.jdbc.JDBCStatement.fetchResult(JDBCStatement.java:1830)
at org.hsqldb.jdbc.JDBCStatement.executeQuery(JDBCStatement.java:181)
at org.hsqldb.jdbc.JDBCDatabaseMetaData.execute(JDBCDatabaseMetaData.java:6150)
at org.hsqldb.jdbc.JDBCDatabaseMetaData.getTables(JDBCDatabaseMetaData.java:3170)
at org.dbunit.database.DefaultMetadataHandler.getTables(DefaultMetadataHandler.java:137)
at org.dbunit.database.DatabaseDataSet.initialize(DatabaseDataSet.java:199)
... 9 more
Caused by: org.hsqldb.HsqlException: java.lang.NullPointerException
at org.hsqldb.error.Error.error(Error.java:108)
at org.hsqldb.result.Result.newErrorResult(Result.java:1069)
at org.hsqldb.StatementDMQL.execute(StatementDMQL.java:192)
at org.hsqldb.Session.executeCompiledStatement(Session.java:1315)
at org.hsqldb.Session.executeDirectStatement(Session.java:1206)
at org.hsqldb.Session.execute(Session.java:990)
at org.hsqldb.jdbc.JDBCStatement.fetchResult(JDBCStatement.java:1822)
... 14 more
Caused by: java.lang.NullPointerException
at org.hsqldb.types.CharacterType.compare(CharacterType.java:418)
at org.hsqldb.index.IndexAVL.compareRowForInsertOrDelete(IndexAVL.java:617)
at org.hsqldb.index.IndexAVLMemory.insert(IndexAVLMemory.java:214)
at org.hsqldb.persist.RowStoreAVL.indexRow(RowStoreAVL.java:171)
at org.hsqldb.persist.RowStoreAVLHybridExtended.indexRow(RowStoreAVLHybridExtended.java:99)
at org.hsqldb.Table.insertSys(Table.java:2625)
at org.hsqldb.dbinfo.DatabaseInformationMain.SYSTEM_TABLES(DatabaseInformationMain.java:2353)
at org.hsqldb.dbinfo.DatabaseInformationMain.generateTable(DatabaseInformationMain.java:348)
at org.hsqldb.dbinfo.DatabaseInformationFull.generateTable(DatabaseInformationFull.java:379)
at org.hsqldb.dbinfo.DatabaseInformationMain.setStore(DatabaseInformationMain.java:507)
at org.hsqldb.persist.PersistentStoreCollectionSession.getStore(PersistentStoreCollectionSession.java:138)
at org.hsqldb.Table.getRowStore(Table.java:2817)
at org.hsqldb.RangeVariable$RangeIteratorMain.(RangeVariable.java:939)
at org.hsqldb.RangeVariable$RangeIteratorMain.(RangeVariable.java:917)
at org.hsqldb.RangeVariable.getIterator(RangeVariable.java:770)
at org.hsqldb.QuerySpecification.buildResult(QuerySpecification.java:1293)
at org.hsqldb.QuerySpecification.getSingleResult(QuerySpecification.java:1245)
at org.hsqldb.QuerySpecification.getResult(QuerySpecification.java:1235)
at org.hsqldb.StatementQuery.getResult(StatementQuery.java:66)
at org.hsqldb.StatementDMQL.execute(StatementDMQL.java:190)
... 18 more我用谷歌搜索，在导出过程中找不到与此类错误相关的任何内容。我对 SQL 或 JDBC 没有那么丰富的经验，所以我希望堆栈跟踪中有足够的信息，以便更有知识的人告诉我出了什么问题。如果有一些其他库可以更好地满足我的需求，那么我可以毫无问题地切换......我现在唯一需要的是使用 XML 导出/导入，所以我没有将 DBUnit 用于其他任何事情。无论如何，如果有人能告诉我出了什么问题，或者我是否应该使用其他东西，我将不胜感激。