程序如果长时间不进行数据库操作，那么数据源中的 Connection 很可能已经断开。其原因有可能是防火墙，或者连接的数据库设置的超时时间。这里使用的是 C3P0 连接 oracle 数据库，引起的异常信息为：
org.springframework.transaction.TransactionSystemException: Could not roll back Hibernate transaction; nested exception is org.hibernate.TransactionException: rollback failed
at org.springframework.orm.hibernate4.HibernateTransactionManager.doRollback(HibernateTransactionManager.java:503)
at org.springframework.transaction.support.AbstractPlatformTransactionManager.processRollback(AbstractPlatformTransactionManager.java:845)
at org.springframework.transaction.support.AbstractPlatformTransactionManager.rollback(AbstractPlatformTransactionManager.java:822)
at org.springframework.transaction.interceptor.TransactionAspectSupport.completeTransactionAfterThrowing(TransactionAspectSupport.java:411)
at org.springframework.transaction.interceptor.TransactionInterceptor.invoke(TransactionInterceptor.java:114)
at org.springframework.aop.framework.ReflectiveMethodInvocation.proceed(ReflectiveMethodInvocation.java:172)
at org.springframework.aop.interceptor.ExposeInvocationInterceptor.invoke(ExposeInvocationInterceptor.java:90)
at org.springframework.aop.framework.ReflectiveMethodInvocation.proceed(ReflectiveMethodInvocation.java:172)
at org.springframework.aop.framework.Cglib2AopProxy$DynamicAdvisedInterceptor.intercept(Cglib2AopProxy.java:622)
at com.platform.dao.TasksDAO$$EnhancerByCGLIB$$abcb28f5.getTaskById(<generated>)
at com.platform.manager.TasksManager.getTaskById(TasksManager.java:287)
at com.platform.manager.TasksManager.checkResult(TasksManager.java:300)
at com.platform.timer.TimerBase.tasksListener(TimerBase.java:149)
at com.platform.timer.TimerBase.run(TimerBase.java:81)
at java.util.TimerThread.mainLoop(Timer.java:555)
at java.util.TimerThread.run(Timer.java:505)
Caused by: org.hibernate.TransactionException: rollback failed
at org.hibernate.engine.transaction.spi.AbstractTransactionImpl.rollback(AbstractTransactionImpl.java:215)
at org.springframework.orm.hibernate4.HibernateTransactionManager.doRollback(HibernateTransactionManager.java:500)
... 15 more
Caused by: org.hibernate.TransactionException: unable to rollback against JDBC connection
at org.hibernate.engine.transaction.internal.jdbc.JdbcTransaction.doRollback(JdbcTransaction.java:167)
at org.hibernate.engine.transaction.spi.AbstractTransactionImpl.rollback(AbstractTransactionImpl.java:209)
... 16 more
Caused by: java.sql.SQLException: 关闭的连接
at oracle.jdbc.driver.DatabaseError.throwSqlException(DatabaseError.java:111)
at oracle.jdbc.driver.DatabaseError.throwSqlException(DatabaseError.java:145)
at oracle.jdbc.driver.DatabaseError.throwSqlException(DatabaseError.java:207)
at oracle.jdbc.driver.PhysicalConnection.rollback(PhysicalConnection.java:1160)
at com.alibaba.china.jdbc.proxy.simple.ConnectionProxy.rollback(ConnectionProxy.java:228)
at com.mchange.v2.c3p0.impl.NewProxyConnection.rollback(NewProxyConnection.java:855)
at org.hibernate.engine.transaction.internal.jdbc.JdbcTransaction.doRollback(JdbcTransaction.java:163)
... 17 more
异常抛出的地方为 Spring 的事务管理 transactionManager，而并非程序代码。即便捕捉到异常，使用 sessionFactory.openSession 也会抛出如下异常：
org.springframework.transaction.TransactionSystemException: Could not roll back Hibernate transaction; nested exception is org.hibernate.TransactionException: rollback failed
at org.springframework.orm.hibernate4.HibernateTransactionManager.doRollback(HibernateTransactionManager.java:503)
at org.springframework.transaction.support.AbstractPlatformTransactionManager.processRollback(AbstractPlatformTransactionManager.java:845)
at org.springframework.transaction.support.AbstractPlatformTransactionManager.rollback(AbstractPlatformTransactionManager.java:822)
at org.springframework.transaction.interceptor.TransactionAspectSupport.completeTransactionAfterThrowing(TransactionAspectSupport.java:411)
at org.springframework.transaction.interceptor.TransactionInterceptor.invoke(TransactionInterceptor.java:114)
at org.springframework.aop.framework.ReflectiveMethodInvocation.proceed(ReflectiveMethodInvocation.java:172)
at org.springframework.aop.interceptor.ExposeInvocationInterceptor.invoke(ExposeInvocationInterceptor.java:90)
at org.springframework.aop.framework.ReflectiveMethodInvocation.proceed(ReflectiveMethodInvocation.java:172)
at org.springframework.aop.framework.Cglib2AopProxy$DynamicAdvisedInterceptor.intercept(Cglib2AopProxy.java:622)
at com.platform.dao.TasksDAO$$EnhancerByCGLIB$$abcb28f5.getTaskByNewSession(<generated>)
at com.platform.manager.TasksManager.checkResult(TasksManager.java:303)
at com.platform.timer.TimerBase.tasksListener(TimerBase.java:149)
at com.platform.timer.TimerBase.run(TimerBase.java:81)
at java.util.TimerThread.mainLoop(Timer.java:555)
at java.util.TimerThread.run(Timer.java:505)
Caused by: org.hibernate.TransactionException: rollback failed
at org.hibernate.engine.transaction.spi.AbstractTransactionImpl.rollback(AbstractTransactionImpl.java:215)
at org.springframework.orm.hibernate4.HibernateTransactionManager.doRollback(HibernateTransactionManager.java:500)
... 14 more
Caused by: org.hibernate.TransactionException: unable to rollback against JDBC connection
at org.hibernate.engine.transaction.internal.jdbc.JdbcTransaction.doRollback(JdbcTransaction.java:167)
at org.hibernate.engine.transaction.spi.AbstractTransactionImpl.rollback(AbstractTransactionImpl.java:209)
... 15 more
Caused by: java.sql.SQLException: Io 异常: Software caused connection abort: recv failed
at oracle.jdbc.driver.DatabaseError.throwSqlException(DatabaseError.java:111)
at oracle.jdbc.driver.DatabaseError.throwSqlException(DatabaseError.java:145)
at oracle.jdbc.driver.DatabaseError.throwSqlException(DatabaseError.java:254)
at oracle.jdbc.driver.T4CConnection.doRollback(T4CConnection.java:577)
at oracle.jdbc.driver.PhysicalConnection.rollback(PhysicalConnection.java:1163)
at com.alibaba.china.jdbc.proxy.simple.ConnectionProxy.rollback(ConnectionProxy.java:228)
at com.mchange.v2.c3p0.impl.NewProxyConnection.rollback(NewProxyConnection.java:855)
at org.hibernate.engine.transaction.internal.jdbc.JdbcTransaction.doRollback(JdbcTransaction.java:163)
... 16 more
解决的办法是：
c3p0 自定义配置：
<!-- 数据库连接声明 -->
<bean id="dataSource" class="com.mchange.v2.c3p0.ComboPooledDataSource"
destroy-method="close">
<property name="driverClass" value="com.alibaba.china.jdbc.SimpleDriver" />
<!-- <property name="driverClass" value="oracle.jdbc.OracleDriver" /> -->
<property name="jdbcUrl" value="jdbc:oracle:thin:@202.116.70.180:61166:orcl" />
<!-- 每60秒检查所有连接池中的空闲连接。Default: 0 -->
<property name="idleConnectionTestPeriod" value="60" />
<!--如果设为true那么在取得连接的同时将校验连接的有效性。Default: false -->
<property name="testConnectionOnCheckin" value="true" />
<!--c3p0将建一张名为Test的空表，并使用其自带的查询语句进行测试。如果定义了这个参数那么 属性preferredTestQuery将被忽略。你不能在这张Test表上进行任何操作，它将只供c3p0测试
使用。Default: null -->
<property name="automaticTestTable" value="Test" />
<property name="properties">
<props>
<prop key="clientEncoding">GBK</prop>
<prop key="serverEncoding">CP1252</prop>
<prop key="user">WDS</prop>
<prop key="password">HelloOracle</prop>
</props>
</property>
</bean>
配置项一定要作为 <bean> 的子元素，而不能做为 <properties> 的子元素，否则不起作用。
参考：
http://my.oschina.net/tianzimensheng/blog/65225
http://www.cnblogs.com/younes/archive/2012/06/01/2529483.html
http://www.cnblogs.com/safeking/archive/2007/02/01/637067.html