当我将C3P0库与休眠3.3.2一起使用时，我遇到了问题。在添加C3P0版本0.9.1和hibernate-C3P0-3.3.2以及hibernate.cfg.xml中的此属性之前，我没有这个问题
<property name="hibernate.connection.provider_class">org.hibernate.connection.C3P0ConnectionProvider</property>
<!-- JDBC connection pool (C3P0) -->
<property name="c3p0.min_size">5</property>
<property name="c3p0.max_size">20</property>
<property name="c3p0.timeout">1800</property>
<property name="c3p0.max_statements">50</property>
之后，我得到一个错误，但我不明白为什么。错误消息是：
com.rcibanque.framework.application.ApplicationException (Cause : com.rcibanque.framework.persistance.PersistanceException (Cause : org.hibernate.exception.GenericJDBCException: Cannot open connection))
at com.rcibanque.common.application.ReferencesService.loadReferences(ReferencesService.java:75)
at com.rcibanque.common.start.InitServlet.init(InitServlet.java:46)
at javax.servlet.GenericServlet.init(GenericServlet.java:215)
at org.apache.catalina.core.StandardWrapper.loadServlet(StandardWrapper.java:1108)
at org.apache.catalina.core.StandardWrapper.load(StandardWrapper.java:1010)
at org.apache.catalina.core.StandardContext.loadOnStartup(StandardContext.java:4413)
at org.apache.catalina.core.StandardContext.start(StandardContext.java:4723)
at org.apache.geronimo.tomcat.GeronimoStandardContext.access$201(GeronimoStandardContext.java:63)
at org.apache.geronimo.tomcat.GeronimoStandardContext$SystemMethodValve.invoke(GeronimoStandardContext.java:398)
at org.apache.geronimo.tomcat.valve.GeronimoBeforeAfterValve.invoke(GeronimoBeforeAfterValve.java:47)
at org.apache.geronimo.tomcat.GeronimoStandardContext.start(GeronimoStandardContext.java:251)
at org.apache.catalina.core.ContainerBase.addChildInternal(ContainerBase.java:799)
at org.apache.catalina.core.ContainerBase.addChild(ContainerBase.java:779)
at org.apache.catalina.core.StandardHost.addChild(StandardHost.java:601)
at org.apache.geronimo.tomcat.TomcatContainer.addContext(TomcatContainer.java:369)
at org.apache.geronimo.tomcat.TomcatWebAppContext.doStart(TomcatWebAppContext.java:512)
at org.apache.geronimo.gbean.runtime.GBeanInstance.createInstance(GBeanInstance.java:998)
at org.apache.geronimo.gbean.runtime.GBeanInstanceState.attemptFullStart(GBeanInstanceState.java:268)
at org.apache.geronimo.gbean.runtime.GBeanInstanceState.start(GBeanInstanceState.java:102)
at org.apache.geronimo.gbean.runtime.GBeanInstance.start(GBeanInstance.java:541)
at org.apache.geronimo.gbean.runtime.GBeanDependency.attemptFullStart(GBeanDependency.java:111)
at org.apache.geronimo.gbean.runtime.GBeanDependency.addTarget(GBeanDependency.java:146)
at org.apache.geronimo.gbean.runtime.GBeanDependency$1.running(GBeanDependency.java:120)
at org.apache.geronimo.kernel.basic.BasicLifecycleMonitor.fireRunningEvent(BasicLifecycleMonitor.java:176)
at org.apache.geronimo.kernel.basic.BasicLifecycleMonitor.access$300(BasicLifecycleMonitor.java:44)
at org.apache.geronimo.kernel.basic.BasicLifecycleMonitor$RawLifecycleBroadcaster.fireRunningEvent(BasicLifecycleMonitor.java:254)
at org.apache.geronimo.gbean.runtime.GBeanInstanceState.attemptFullStart(GBeanInstanceState.java:294)
at org.apache.geronimo.gbean.runtime.GBeanInstanceState.start(GBeanInstanceState.java:102)
at org.apache.geronimo.gbean.runtime.GBeanInstanceState.startRecursive(GBeanInstanceState.java:124)
at org.apache.geronimo.gbean.runtime.GBeanInstance.startRecursive(GBeanInstance.java:555)
at org.apache.geronimo.kernel.basic.BasicKernel.startRecursiveGBean(BasicKernel.java:379)
at org.apache.geronimo.kernel.config.ConfigurationUtil.startConfigurationGBeans(ConfigurationUtil.java:456)
at org.apache.geronimo.kernel.config.ConfigurationUtil.startConfigurationGBeans(ConfigurationUtil.java:493)
at org.apache.geronimo.kernel.config.KernelConfigurationManager.start(KernelConfigurationManager.java:188)
at org.apache.geronimo.kernel.config.SimpleConfigurationManager.startConfiguration(SimpleConfigurationManager.java:563)
at org.apache.geronimo.kernel.config.SimpleConfigurationManager.startConfiguration(SimpleConfigurationManager.java:544)
at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:57)
at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
at java.lang.reflect.Method.invoke(Method.java:606)
at org.apache.geronimo.gbean.runtime.ReflectionMethodInvoker.invoke(ReflectionMethodInvoker.java:34)
at org.apache.geronimo.gbean.runtime.GBeanOperation.invoke(GBeanOperation.java:124)
at org.apache.geronimo.gbean.runtime.GBeanInstance.invoke(GBeanInstance.java:867)
at org.apache.geronimo.kernel.basic.BasicKernel.invoke(BasicKernel.java:239)
at org.apache.geronimo.kernel.KernelGBean.invoke(KernelGBean.java:342)
at sun.reflect.GeneratedMethodAccessor129.invoke(Unknown Source)
at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
at java.lang.reflect.Method.invoke(Method.java:606)
at org.apache.geronimo.gbean.runtime.ReflectionMethodInvoker.invoke(ReflectionMethodInvoker.java:34)
at org.apache.geronimo.gbean.runtime.GBeanOperation.invoke(GBeanOperation.java:124)
at org.apache.geronimo.gbean.runtime.GBeanInstance.invoke(GBeanInstance.java:867)
at org.apache.geronimo.kernel.basic.BasicKernel.invoke(BasicKernel.java:239)
at org.apache.geronimo.system.jmx.MBeanGBeanBridge.invoke(MBeanGBeanBridge.java:172)
at com.sun.jmx.interceptor.DefaultMBeanServerInterceptor.invoke(DefaultMBeanServerInterceptor.java:819)
at com.sun.jmx.mbeanserver.JmxMBeanServer.invoke(JmxMBeanServer.java:801)
at javax.management.remote.rmi.RMIConnectionImpl.doOperation(RMIConnectionImpl.java:1487)
at javax.management.remote.rmi.RMIConnectionImpl.access$300(RMIConnectionImpl.java:97)
at javax.management.remote.rmi.RMIConnectionImpl$PrivilegedOperation.run(RMIConnectionImpl.java:1328)
at java.security.AccessController.doPrivileged(Native Method)
at javax.management.remote.rmi.RMIConnectionImpl.doPrivilegedOperation(RMIConnectionImpl.java:1427)
at javax.management.remote.rmi.RMIConnectionImpl.invoke(RMIConnectionImpl.java:848)
at sun.reflect.GeneratedMethodAccessor117.invoke(Unknown Source)
at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
at java.lang.reflect.Method.invoke(Method.java:606)
at sun.rmi.server.UnicastServerRef.dispatch(UnicastServerRef.java:322)
at sun.rmi.transport.Transport$1.run(Transport.java:177)
at sun.rmi.transport.Transport$1.run(Transport.java:174)
at java.security.AccessController.doPrivileged(Native Method)
at sun.rmi.transport.Transport.serviceCall(Transport.java:173)
at sun.rmi.transport.tcp.TCPTransport.handleMessages(TCPTransport.java:556)
at sun.rmi.transport.tcp.TCPTransport$ConnectionHandler.run0(TCPTransport.java:811)
at sun.rmi.transport.tcp.TCPTransport$ConnectionHandler.run(TCPTransport.java:670)
at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1145)
at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:615)
at java.lang.Thread.run(Thread.java:745)
Caused by: com.rcibanque.framework.persistance.PersistanceException (Cause : org.hibernate.exception.GenericJDBCException: Cannot open connection)
at com.rcibanque.framework.persistance.hibernate.HibernateTransaction.begin(HibernateTransaction.java:65)
at com.rcibanque.common.application.ReferencesService.loadReferences(ReferencesService.java:52)
... 74 more
Caused by: org.hibernate.exception.GenericJDBCException: Cannot open connection
at org.hibernate.exception.SQLStateConverter.handledNonSpecificException(SQLStateConverter.java:126)
at org.hibernate.exception.SQLStateConverter.convert(SQLStateConverter.java:114)
at org.hibernate.exception.JDBCExceptionHelper.convert(JDBCExceptionHelper.java:66)
at org.hibernate.exception.JDBCExceptionHelper.convert(JDBCExceptionHelper.java:52)
at org.hibernate.jdbc.ConnectionManager.openConnection(ConnectionManager.java:449)
at org.hibernate.jdbc.ConnectionManager.getConnection(ConnectionManager.java:167)
at org.hibernate.jdbc.JDBCContext.connection(JDBCContext.java:142)
at org.hibernate.transaction.JDBCTransaction.begin(JDBCTransaction.java:85)
at org.hibernate.impl.SessionImpl.beginTransaction(SessionImpl.java:1354)
at com.rcibanque.framework.persistance.hibernate.HibernateTransaction.begin(HibernateTransaction.java:63)
... 75 more
Caused by: java.sql.SQLException: Connections could not be acquired from the underlying database!
at com.mchange.v2.sql.SqlUtils.toSQLException(SqlUtils.java:106)
at com.mchange.v2.c3p0.impl.C3P0PooledConnectionPool.checkoutPooledConnection(C3P0PooledConnectionPool.java:529)
at com.mchange.v2.c3p0.impl.AbstractPoolBackedDataSource.getConnection(AbstractPoolBackedDataSource.java:128)
at org.hibernate.connection.C3P0ConnectionProvider.getConnection(C3P0ConnectionProvider.java:78)
at org.hibernate.jdbc.ConnectionManager.openConnection(ConnectionManager.java:446)
... 80 more
Caused by: com.mchange.v2.resourcepool.CannotAcquireResourceException: A ResourcePool could not acquire a resource from its primary factory or source.
at com.mchange.v2.resourcepool.BasicResourcePool.awaitAvailable(BasicResourcePool.java:1319)
at com.mchange.v2.resourcepool.BasicResourcePool.prelimCheckoutResource(BasicResourcePool.java:557)
at com.mchange.v2.resourcepool.BasicResourcePool.checkoutResource(BasicResourcePool.java:477)
at com.mchange.v2.c3p0.impl.C3P0PooledConnectionPool.checkoutPooledConnection(C3P0PooledConnectionPool.java:525)
... 83 more
有人可以帮助我解决此问题吗？ 非常感谢。