接分：eclipse+hibernate出现的问题？在线等待，急！！！！

(cfg.Environment                     483 ) Hibernate 2.1.8
(cfg.Environment                     512 ) hibernate.properties not found
(cfg.Environment                     543 ) using CGLIB reflection optimizer
(cfg.Environment                     572 ) using JDK 1.4 java.sql.Timestamp handling
(cfg.Configuration                   909 ) configuring from resource: /hibernate.cfg.xml
(cfg.Configuration                   881 ) Configuration resource: /hibernate.cfg.xml
(cfg.Configuration                   332 ) Mapping resource: xzl/hibernate/user.hbm.xml
(cfg.Binder                          229 ) Mapping class: xzl.hibernate.User -> usertable
(cfg.Configuration                   1067) Configured SessionFactory: null
(cfg.Configuration                   641 ) processing one-to-many association mappings
(cfg.Configuration                   650 ) processing one-to-one association property references
(cfg.Configuration                   675 ) processing foreign key constraints
(dialect.Dialect                     86  ) Using dialect: net.sf.hibernate.dialect.MySQLDialect
(cfg.SettingsFactory                 70  ) Maximim outer join fetch depth: 2
(cfg.SettingsFactory                 74  ) Use outer join fetching: true
(connection.DriverManagerConnectionProvider 42  ) Using Hibernate built-in connection pool (not for production use!)
(connection.DriverManagerConnectionProvider 43  ) Hibernate connection pool size: 20
---------------以下就是出现问题的部分-------------------------------------
Exception in thread "main" java.lang.NoClassDefFoundError: org/aspectj/lang/Signature
at java.lang.Class.forName0(Native Method)
at java.lang.Class.forName(Class.java:164)
at net.sf.hibernate.connection.DriverManagerConnectionProvider.configure(DriverManagerConnectionProvider.java:55)
at net.sf.hibernate.connection.ConnectionProviderFactory.newConnectionProvider(ConnectionProviderFactory.java:83)
at net.sf.hibernate.cfg.SettingsFactory.buildSettings(SettingsFactory.java:76)
at net.sf.hibernate.cfg.Configuration.buildSettings(Configuration.java:1172)
at net.sf.hibernate.cfg.Configuration.buildSessionFactory(Configuration.java:803)
at xzl.hibernate.Test.main(Test.java:21)
是什么问题？