使用Hibernate和C3p0连接池遇到的问题

Question

我正在使用hibernate 4.3.0和c3p0池测试Web应用程序，有时在重新加载上下文后会出现以下错误：

 INFO: Reloading Context with name [/AppName] is completed
    янв 07, 2015 12:07:14 AM org.apache.catalina.loader.WebappClassLoader loadClass
    INFO: Illegal access: this web application instance has been stopped already.  Could not load com.mchange.v2.resourcepool.BasicResourcePool$AsyncTestIdleResourceTask.  The eventual following stack trace is caused by an error thrown for debugging purposes as well as to attempt to terminate the thread which caused the illegal access, and has no functional impact.
    java.lang.IllegalStateException
        at org.apache.catalina.loader.WebappClassLoader.loadClass(WebappClassLoader.java:1612)
        at org.apache.catalina.loader.WebappClassLoader.loadClass(WebappClassLoader.java:1571)
        at com.mchange.v2.resourcepool.BasicResourcePool.checkIdleResources(BasicResourcePool.java:1584)
        at com.mchange.v2.resourcepool.BasicResourcePool.access$2000(BasicResourcePool.java:44)
        at com.mchange.v2.resourcepool.BasicResourcePool$CheckIdleResourcesTask.run(BasicResourcePool.java:2116)
        at java.util.TimerThread.mainLoop(Timer.java:555)
        at java.util.TimerThread.run(Timer.java:505)

Exception in thread "C3P0PooledConnectionPoolManager[identityToken->1hge136961hmilhm17ylc97|17d425e]-AdminTaskTimer" java.lang.NoClassDefFoundError: com/mchange/v2/resourcepool/BasicResourcePool$AsyncTestIdleResourceTask
    at com.mchange.v2.resourcepool.BasicResourcePool.checkIdleResources(BasicResourcePool.java:1584)
    at com.mchange.v2.resourcepool.BasicResourcePool.access$2000(BasicResourcePool.java:44)
    at com.mchange.v2.resourcepool.BasicResourcePool$CheckIdleResourcesTask.run(BasicResourcePool.java:2116)
    at java.util.TimerThread.mainLoop(Timer.java:555)
    at java.util.TimerThread.run(Timer.java:505)
Caused by: java.lang.ClassNotFoundException: com.mchange.v2.resourcepool.BasicResourcePool$AsyncTestIdleResourceTask
    at org.apache.catalina.loader.WebappClassLoader.loadClass(WebappClassLoader.java:1720)
    at org.apache.catalina.loader.WebappClassLoader.loadClass(WebappClassLoader.java:1571)
    ... 5 more

依赖项 - 或许只需要hibernate-c3p0依赖？

<dependency>
    <groupId>com.mchange</groupId>
    <artifactId>c3p0</artifactId>
    <version>0.9.2.1</version>
</dependency>

<dependency>
    <groupId>org.hibernate</groupId>
    <artifactId>hibernate-c3p0</artifactId>
    <version>4.3.0.Final</version>
</dependency>

Hibernate设置

<property name="connection.provider_class">org.hibernate.connection.C3P0ConnectionProvider</property>

        <property name="hibernate.c3p0.min_size">5</property>
        <property name="hibernate.c3p0.max_size">20</property>
        <property name="hibernate.c3p0.timeout">3000</property>
        <property name="hibernate.c3p0.max_statements">50</property>
        <property name="hibernate.c3p0.idle_test_period">300</property>

那个错误的原因是什么，如何修复它？ 所有与hibernate-c3p0相关的依赖项都已在类路径中。

- andy007

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这个问题可能与以下内容相关：http://stackoverflow.com/questions/19905673/how-to-re-deploy-a-hibernate-c3p0-project-on-tomcat-7-without-getting-strange-c3 - Mike R

同样相关：https://forums.hibernate.org/viewtopic.php?t=924835&view=next&sid=abc532479937768dd0fd58e82a1f465f - Mike R

Answer 1

请参考我添加的链接（作为注释）。在重新部署期间，类会被卸载，如果您没有关闭Hibernate的sessionFactory，则会出现ClassNotFound错误。其中一个答案建议您添加自定义的ServletContextListener来处理contextDestroyed事件。

- Mike R