请问出现这种异常是什么原因,谢谢

[pyzs2004]

2007-05-11 15:59:07,133 WARN [org.jboss.resource.adapter.jdbc.local.LocalManagedConnectionFactory] Destroying connection that is not valid, due to the following exception: oracle.jdbc.driver.T4CConnection@19380c1
java.sql.SQLException: pingDatabase failed status=-1
at org.jboss.resource.adapter.jdbc.vendor.OracleValidConnectionChecker.isValidConnection(OracleValidConnectionChecker.java:72)
at org.jboss.resource.adapter.jdbc.BaseWrapperManagedConnectionFactory.isValidConnection(BaseWrapperManagedConnectionFactory.java:389)
at org.jboss.resource.adapter.jdbc.BaseWrapperManagedConnection.checkValid(BaseWrapperManagedConnection.java:230)
at org.jboss.resource.adapter.jdbc.local.LocalManagedConnectionFactory.matchManagedConnections(LocalManagedConnectionFactory.java:192)
at org.jboss.resource.connectionmanager.InternalManagedConnectionPool.getConnection(InternalManagedConnectionPool.java:187)
at org.jboss.resource.connectionmanager.JBossManagedConnectionPool$BasePool.getConnection(JBossManagedConnectionPool.java:574)
at org.jboss.resource.connectionmanager.BaseConnectionManager2.getManagedConnection(BaseConnectionManager2.java:475)
at org.jboss.resource.connectionmanager.TxConnectionManager.getManagedConnection(TxConnectionManager.java:317)
at org.jboss.resource.connectionmanager.BaseConnectionManager2.allocateConnection(BaseConnectionManager2.java:527)
at org.jboss.resource.connectionmanager.BaseConnectionManager2$ConnectionManagerProxy.allocateConnection(BaseConnectionManager2.java:926)
at org.jboss.resource.adapter.jdbc.WrapperDataSource.getConnection(WrapperDataSource.java:88)