大侠帮忙看看 引起这些异常的原因可能有哪些，，，


net.sf.hibernate.TransactionException: Begin failed with SQL exception: 
at net.sf.hibernate.transaction.JDBCTransaction.begin(JDBCTransaction.java:49)
at net.sf.hibernate.transaction.JDBCTransactionFactory.beginTransaction(JDBCTransactionFactory.java:19)
at net.sf.hibernate.impl.SessionImpl.beginTransaction(SessionImpl.java:2195)
at cn.com.youtong.apollo.check.db.DBAccountCheck.clearUnit(DBAccountCheck.java:903)
at cn.com.youtong.apollo.servlet.AccountServlet.diffAdjust(AccountServlet.java:750)
at cn.com.youtong.apollo.servlet.AccountServlet.service(AccountServlet.java:193)
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 org.apache.catalina.core.ApplicationDispatcher.invoke(ApplicationDispatcher.java:654)
at org.apache.catalina.core.ApplicationDispatcher.processRequest(ApplicationDispatcher.java:445)
at org.apache.catalina.core.ApplicationDispatcher.doForward(ApplicationDispatcher.java:379)
at org.apache.catalina.core.ApplicationDispatcher.forward(ApplicationDispatcher.java:292)
at cn.com.youtong.apollo.servlet.ModelServlet.perform(ModelServlet.java:2140)
at cn.com.youtong.apollo.servlet.RootServlet.service(RootServlet.java:155)
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 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)
Caused by: java.sql.SQLException: You can't operate on a closed connection!!!
at com.mchange.v2.c3p0.impl.C3P0PooledConnection$ProxyConnectionInvocationHandler.invoke(C3P0PooledConnection.java:715)
at com.mchange.v2.c3p0.impl.$Proxy2.getAutoCommit(Unknown Source)
at net.sf.hibernate.transaction.JDBCTransaction.begin(JDBCTransaction.java:40)
... 27 more