我正在尝试更新一个对象但是hibernate试图在数据库中新插入对象，因此我收到了一个违规错误，因为该对象已经存在于数据库中。
例如。
Category X= getCategory();//returns me a category which i then update
Transaction tx = null;
try
{
tx=session.beginTransaction();
tx.begin();
session.Update(X);
tx.commit();
return true;
}
catch (Exception e)
{
tx.rollback();
e.printStackTrace();
return false;
}
我收到此错误，因为该类别已存在于数据库中
org.hibernate.exception.ConstraintViolationException: Could not execute JDBC batch update
我通过使用session.update，hibernate自动更新对象。有没有人知道如何更新而不写sql ??
完整错误：
Hibernate: select nextval ('hibernate_sequence')
Hibernate: select nextval ('hibernate_sequence')
Hibernate: select nextval ('hibernate_sequence')
Hibernate: select nextval ('hibernate_sequence')
Hibernate: insert into CATEGORY (CATEGORYNAME, PARENT_CATEGORY_ID, CATEGORYID) values (?, ?, ?)
org.hibernate.exception.ConstraintViolationException: Could not execute JDBC batch update
at org.hibernate.exception.SQLStateConverter.convert(SQLStateConverter.java:96)
at org.hibernate.exception.JDBCExceptionHelper.convert(JDBCExceptionHelper.java:66)
at org.hibernate.jdbc.AbstractBatcher.executeBatch(AbstractBatcher.java:275)
at org.hibernate.jdbc.AbstractBatcher.prepareStatement(AbstractBatcher.java:114)
at org.hibernate.jdbc.AbstractBatcher.prepareStatement(AbstractBatcher.java:109)
at org.hibernate.jdbc.AbstractBatcher.prepareBatchStatement(AbstractBatcher.java:244)
at org.hibernate.persister.entity.AbstractEntityPersister.insert(AbstractEntityPersister.java:2395)
at org.hibernate.persister.entity.AbstractEntityPersister.insert(AbstractEntityPersister.java:2858)
at org.hibernate.action.EntityInsertAction.execute(EntityInsertAction.java:79)
at org.hibernate.engine.ActionQueue.execute(ActionQueue.java:268)
at org.hibernate.engine.ActionQueue.executeActions(ActionQueue.java:260)
at org.hibernate.engine.ActionQueue.executeActions(ActionQueue.java:179)
at org.hibernate.event.def.AbstractFlushingEventListener.performExecutions(AbstractFlushingEventListener.java:321)
at org.hibernate.event.def.DefaultFlushEventListener.onFlush(DefaultFlushEventListener.java:51)
at org.hibernate.impl.SessionImpl.flush(SessionImpl.java:1206)
at org.hibernate.impl.SessionImpl.managedFlush(SessionImpl.java:375)
at org.hibernate.transaction.JDBCTransaction.commit(JDBCTransaction.java:137)
at com.BiddingSystem.server.ServiceImpl.TestSaveCategory(ServiceImpl.java:280)
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 net.sf.gilead.gwt.PersistentRemoteService.processCall(PersistentRemoteService.java:174)
at com.google.gwt.user.server.rpc.RemoteServiceServlet.processPost(RemoteServiceServlet.java:243)
at com.google.gwt.user.server.rpc.AbstractRemoteServiceServlet.doPost(AbstractRemoteServiceServlet.java:62)
at javax.servlet.http.HttpServlet.service(HttpServlet.java:637)
at javax.servlet.http.HttpServlet.service(HttpServlet.java:717)
at org.mortbay.jetty.servlet.ServletHolder.handle(ServletHolder.java:487)
at org.mortbay.jetty.servlet.ServletHandler.handle(ServletHandler.java:362)
at org.mortbay.jetty.security.SecurityHandler.handle(SecurityHandler.java:216)
at org.mortbay.jetty.servlet.SessionHandler.handle(SessionHandler.java:181)
at org.mortbay.jetty.handler.ContextHandler.handle(ContextHandler.java:729)
at org.mortbay.jetty.webapp.WebAppContext.handle(WebAppContext.java:405)
at org.mortbay.jetty.handler.HandlerWrapper.handle(HandlerWrapper.java:152)
at org.mortbay.jetty.handler.RequestLogHandler.handle(RequestLogHandler.java:49)
at org.mortbay.jetty.handler.HandlerWrapper.handle(HandlerWrapper.java:152)
at org.mortbay.jetty.Server.handle(Server.java:324)
at org.mortbay.jetty.HttpConnection.handleRequest(HttpConnection.java:505)
at org.mortbay.jetty.HttpConnection$RequestHandler.content(HttpConnection.java:843)
at org.mortbay.jetty.HttpParser.parseNext(HttpParser.java:647)
at org.mortbay.jetty.HttpParser.parseAvailable(HttpParser.java:211)
at org.mortbay.jetty.HttpConnection.handle(HttpConnection.java:380)
at org.mortbay.io.nio.SelectChannelEndPoint.run(SelectChannelEndPoint.java:395)
at org.mortbay.thread.QueuedThreadPool$PoolThread.run(QueuedThreadPool.java:488)
Caused by: java.sql.BatchUpdateException: Batch entry 0 insert into CATEGORY (CATEGORYNAME, PARENT_CATEGORY_ID, CATEGORYID) values ('Laptop', '0', '397') was aborted. Call getNextException to see the cause.
at org.postgresql.jdbc2.AbstractJdbc2Statement$BatchResultHandler.handleError(AbstractJdbc2Statement.java:2598)
at org.postgresql.core.v3.QueryExecutorImpl.processResults(QueryExecutorImpl.java:1836)
at org.postgresql.core.v3.QueryExecutorImpl.execute(QueryExecutorImpl.java:407)
at org.postgresql.jdbc2.AbstractJdbc2Statement.executeBatch(AbstractJdbc2Statement.java:2737)
at org.hibernate.jdbc.BatchingBatcher.doExecuteBatch(BatchingBatcher.java:70)
at org.hibernate.jdbc.AbstractBatcher.executeBatch(AbstractBatcher.java:268)
... 41 more
答案 0 :(得分：1)
如果没有看到getCategory()的内容，就很难回答你的问题。根据hibernate文档，Session.update期望传递一个分离的实体，该实体是由先前会话中的Session.load（）或Session.get（）返回的实体。关闭。
事实证明，在正常的休眠使用中，很少需要更新。这是因为hibernate可以自动检测对象的更改。这是一种更常见的模式：
Transaction tx = null;
try
{
tx=session.beginTransaction();
tx.begin();
Category X = session.load(Category.class,[categoryId])
X.setXXX(...) // update the category
tx.commit();
return true;
}
catch (Exception e)
{
tx.rollback();
e.printStackTrace();
return false;
}
提交后，hibernate将知道从Load返回的类别已被修改，并将自动向数据库发出更新。
更正式地说，hibernate将自动检测对持久性实体所做的更改，并在提交事务时自动发出UPDATE。持久化实体是从Session.get，Session.load或任何会话查询函数返回的任何实体。
有关持久性，分离式和瞬态对象的更多信息，请点击此处
http://docs.jboss.org/hibernate/core/3.3/reference/en/html/objectstate.html#objectstate-overview