java - 从双表生成 UUID

Question

我想为唯一的字符串生成 UUID，我使用以下代码:-

thread.createSession();
HexGenerator gen1 = new HexGenerator();
gen1.setHexId("2");
thread.ses.save(gen1);
gen1 = (HexGenerator) thread.ses.load(HexGenerator.class, gen1.getHexId());
System.out.println("gen1-->" + gen1.getHexId());
thread.commit();

下面是我的 hibernate 文件:-

<class name="entity.HexGenerator" table="dual">
    <id name="hexId" type="string" unsaved-value="null">
        <generator class="uuid.hex"/>
    </id>
</class>

UUId 已正确生成，但在提交完整事务时出现错误。如出现以下错误。

Exception in thread "main" - Could not synchronize database state with session
org.hibernate.exception.SQLGrammarException: Could not execute JDBC batch update
    at org.hibernate.exception.SQLStateConverter.convert(SQLStateConverter.java:67)
    at org.hibernate.exception.JDBCExceptionHelper.convert(JDBCExceptionHelper.java:43)
    at org.hibernate.jdbc.AbstractBatcher.executeBatch(AbstractBatcher.java:253)
    at org.hibernate.engine.ActionQueue.executeActions(ActionQueue.java:237)
    at org.hibernate.engine.ActionQueue.executeActions(ActionQueue.java:141)
    at org.hibernate.event.def.AbstractFlushingEventListener.performExecutions(AbstractFlushingEventListener.java:298)
    at org.hibernate.event.def.DefaultFlushEventListener.onFlush(DefaultFlushEventListener.java:27)
    at org.hibernate.impl.SessionImpl.flush(SessionImpl.java:1000)
    at org.hibernate.impl.SessionImpl.managedFlush(SessionImpl.java:338)
    at org.hibernate.transaction.JDBCTransaction.commit(JDBCTransaction.java:106)
    at com.ofss.test.hibernate.HibernateThread.commit(HibernateThread.java:29)
    at com.ofss.test.hibernate.HibernateThread.main(HibernateThread.java:57)
Caused by: java.sql.BatchUpdateException: ORA-00904: "HEXID": invalid identifier

    at oracle.jdbc.driver.DatabaseError.throwBatchUpdateException(DatabaseError.java:343)
    at oracle.jdbc.driver.OraclePreparedStatement.executeBatch(OraclePreparedStatement.java:10698)
    at org.hibernate.jdbc.BatchingBatcher.doExecuteBatch(BatchingBatcher.java:48)
    at org.hibernate.jdbc.AbstractBatcher.executeBatch(AbstractBatcher.java:246)
    ... 9 more
org.hibernate.exception.SQLGrammarException: Could not execute JDBC batch update
    at org.hibernate.exception.SQLStateConverter.convert(SQLStateConverter.java:67)
    at org.hibernate.exception.JDBCExceptionHelper.convert(JDBCExceptionHelper.java:43)
    at org.hibernate.jdbc.AbstractBatcher.executeBatch(AbstractBatcher.java:253)
    at org.hibernate.engine.ActionQueue.executeActions(ActionQueue.java:237)
    at org.hibernate.engine.ActionQueue.executeActions(ActionQueue.java:141)
    at org.hibernate.event.def.AbstractFlushingEventListener.performExecutions(AbstractFlushingEventListener.java:298)
    at org.hibernate.event.def.DefaultFlushEventListener.onFlush(DefaultFlushEventListener.java:27)
    at org.hibernate.impl.SessionImpl.flush(SessionImpl.java:1000)
    at org.hibernate.impl.SessionImpl.managedFlush(SessionImpl.java:338)
    at org.hibernate.transaction.JDBCTransaction.commit(JDBCTransaction.java:106)
    at com.ofss.test.hibernate.HibernateThread.commit(HibernateThread.java:29)
    at com.ofss.test.hibernate.HibernateThread.main(HibernateThread.java:57)
Caused by: java.sql.BatchUpdateException: ORA-00904: "HEXID": invalid identifier

    at oracle.jdbc.driver.DatabaseError.throwBatchUpdateException(DatabaseError.java:343)
    at oracle.jdbc.driver.OraclePreparedStatement.executeBatch(OraclePreparedStatement.java:10698)
    at org.hibernate.jdbc.BatchingBatcher.doExecuteBatch(BatchingBatcher.java:48)
    at org.hibernate.jdbc.AbstractBatcher.executeBatch(AbstractBatcher.java:246)

Answer 1

您无法在 Oracle dual 虚拟表上插入或更新。您只需在 select 查询中使用它即可。因此，您的行 thread.ses.save(gen1) 就是生成错误的原因。我认为如果你删除这一行，错误就会被修复。

但我真的不明白为什么你需要访问数据库来生成 UUID，它似乎是在 HexGenerator 类中生成的(或者可能是在 hibernate 文件引用的“uuid.gen”类中生成的)。