hibernate关闭连接问题

 最近在项目中尝试将hibernate融入现有的体系中来，对项目中部分crud操作使用了hibernate来做持久化，测试中未出现问题(没做压力测试..)，正式部署之后出现每3-4小时使用hibernate部分做操作会提示关闭的连接，没有用的部分读写数据库正常
提示如下：
2008-03-26 14:45:18,383-[TS] DEBUG http8888-Processor6 org.hibernate.transaction.JDBCTransaction - begin
2008-03-26 14:45:18,383-[TS] DEBUG http8888-Processor6 org.hibernate.jdbc.ConnectionManager - opening JDBC connection
2008-03-26 14:45:18,383-[TS] DEBUG http8888-Processor6 org.hibernate.connection.DriverManagerConnectionProvider - total checked-out connections: 0
2008-03-26 14:45:18,383-[TS] DEBUG http8888-Processor6 org.hibernate.connection.DriverManagerConnectionProvider - using pooled JDBC connection, pool size: 0
2008-03-26 14:45:18,383-[TS] DEBUG http8888-Processor6 org.hibernate.transaction.JDBCTransaction - current autocommit status: false
2008-03-26 14:45:18,398-[TS] DEBUG http8888-Processor6 org.hibernate.jdbc.JDBCContext - after transaction begin
2008-03-26 14:45:18,398-[TS] DEBUG http8888-Processor6 org.hibernate.jdbc.AbstractBatcher - about to open PreparedStatement (open PreparedStatements: 0, globally: 3)
2008-03-26 14:45:18,398-[TS] DEBUG http8888-Processor6 org.hibernate.SQL - select rollshowte0_.RSID as RSID0_, rollshowte0_.regionid as regionid0_, rollshowte0_.texttype as texttype0_, rollshowte0_.texttitle as texttitle0_, rollshowte0_.textcontent as textcont5_0_, rollshowte0_.status as status0_, rollshowte0_.BEGINTIME as BEGINTIME0_, rollshowte0_.ENDTIME as ENDTIME0_, rollshowte0_.CREATETIME as CREATETIME0_, rollshowte0_.EDITTIME as EDITTIME0_ from ROLLSHOWTEXT rollshowte0_ where rollshowte0_.regionid=2 and rollshowte0_.texttype=1 and rollshowte0_.status=1
2008-03-26 14:45:18,414-[TS] DEBUG http8888-Processor6 org.hibernate.jdbc.AbstractBatcher - preparing statement
2008-03-26 14:45:18,430-[TS] WARN http8888-Processor6 org.hibernate.util.JDBCExceptionReporter - SQL Error: 17008, SQLState: null
2008-03-26 14:45:18,430-[TS] ERROR http8888-Processor6 org.hibernate.util.JDBCExceptionReporter - 关闭的连接
2008-03-26 14:45:18,430-[TS] DEBUG http8888-Processor6 org.hibernate.transaction.JDBCTransaction - rollback
2008-03-26 14:45:18,430-[TS] ERROR http8888-Processor6 org.hibernate.transaction.JDBCTransaction - JDBC rollback failed
java.sql.SQLException: 关闭的连接
    at oracle.jdbc.dbaccess.DBError.throwSqlException(DBError.java:134)
    at oracle.jdbc.dbaccess.DBError.throwSqlException(DBError.java:179)
    at oracle.jdbc.dbaccess.DBError.throwSqlException(DBError.java:269)
    at oracle.jdbc.driver.OracleConnection.rollback(OracleConnection.java:1439)
    at org.hibernate.transaction.JDBCTransaction.rollbackAndResetAutoCommit(JDBCTransaction.java:183)
    at org.hibernate.transaction.JDBCTransaction.rollback(JDBCTransaction.java:162)
    at com.lucifer.itg.manager.RollShowDAO.retrieveRoll(RollShowDAO.java:79)
    at com.lucifer.itg.action.RollTextAction.execute(RollTextAction.java:81)
    at org.apache.struts.action.RequestProcessor.processActionPerform(RequestProcessor.java:421)
    at org.apache.struts.action.RequestProcessor.process(RequestProcessor.java:226)
    at org.apache.struts.action.ActionServlet.process(ActionServlet.java:1164)
    at org.apache.struts.action.ActionServlet.doGet(ActionServlet.java:397)
    at javax.servlet.http.HttpServlet.service(HttpServlet.java:743)
    at javax.servlet.http.HttpServlet.service(HttpServlet.java:856)
    at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:284)
    at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:204)
    at net.wasu.platform.filter.EncodingFilter.doFilter(EncodingFilter.java:30)
    at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:233)
    at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:204)
    at org.apache.catalina.core.StandardWrapperValve.invoke(StandardWrapperValve.java:256)
    at org.apache.catalina.core.StandardValveContext.invokeNext(StandardValveContext.java:151)
    at org.apache.catalina.core.StandardPipeline.invoke(StandardPipeline.java:564)
    at org.apache.catalina.core.StandardContextValve.invokeInternal(StandardContextValve.java:245)
    at org.apache.catalina.core.StandardContextValve.invoke(StandardContextValve.java:199)
    at org.apache.catalina.core.StandardValveContext.invokeNext(StandardValveContext.java:151)
    at org.apache.catalina.core.StandardPipeline.invoke(StandardPipeline.java:564)
    at org.apache.catalina.core.StandardHostValve.invoke(StandardHostValve.java:195)
    at org.apache.catalina.core.StandardValveContext.invokeNext(StandardValveContext.java:151)
    at org.apache.catalina.valves.ErrorReportValve.invoke(ErrorReportValve.java:164)
    at org.apache.catalina.core.StandardValveContext.invokeNext(StandardValveContext.java:149)
    at org.apache.catalina.core.StandardPipeline.invoke(StandardPipeline.java:564)
    at org.apache.catalina.core.StandardEngineValve.invoke(StandardEngineValve.java:156)
    at org.apache.catalina.core.StandardValveContext.invokeNext(StandardValveContext.java:151)
    at org.apache.catalina.core.StandardPipeline.invoke(StandardPipeline.java:564)
    at org.apache.catalina.core.Contai