Hibernate Servlet出错，搞了几天了，求大神给看看
这个是错误信息：
org.hibernate.MappingException: could not instantiate id generator
at org.hibernate.id.IdentifierGeneratorFactory.create(IdentifierGeneratorFactory.java:98)
at org.hibernate.mapping.SimpleValue.createIdentifierGenerator(SimpleValue.java:152)
at org.hibernate.impl.SessionFactoryImpl.<init>(SessionFactoryImpl.java:192)
at org.hibernate.cfg.Configuration.buildSessionFactory(Configuration.java:1294)
at jrdn.jcy.daoimpl.UserDaoImpl.checkUserLogin(UserDaoImpl.java:22)
at jrdn.jcy.action.UserAction.userLogin(UserAction.java:115)
at jrdn.jcy.action.UserAction.doPost(UserAction.java:78)
at javax.servlet.http.HttpServlet.service(HttpServlet.java:710)
at javax.servlet.http.HttpServlet.service(HttpServlet.java:803)
at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:290)
at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:206)
at jrdn.jcy.util.EncodingFilter.doFilter(EncodingFilter.java:22)
at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:235)
at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:206)
at org.apache.catalina.core.StandardWrapperValve.invoke(StandardWrapperValve.java:230)
at org.apache.catalina.core.StandardContextValve.invoke(StandardContextValve.java:175)
at org.apache.catalina.core.StandardHostValve.invoke(StandardHostValve.java:128)
at org.apache.catalina.valves.ErrorReportValve.invoke(ErrorReportValve.java:104)
at org.apache.catalina.core.StandardEngineValve.invoke(StandardEngineValve.java:109)
at org.apache.catalina.connector.CoyoteAdapter.service(CoyoteAdapter.java:261)
at org.apache.coyote.http11.Http11Processor.process(Http11Processor.java:844)
at org.apache.coyote.http11.Http11Protocol$Http11ConnectionHandler.process(Http11Protocol.java:581)
at org.apache.tomcat.util.net.JIoEndpoint$Worker.run(JIoEndpoint.java:447)
at java.lang.Thread.run(Thread.java:619)

------解决方案--------------------
看看你的数据库是否支持assigned这种主键生成策略。。。
------解决方案--------------------

探讨

我的id是自己添加，所以没有sequence引用:

主键生成方式改成

<generator class="sequence">
<param name="sequence">你的sequence</param>
</generator>