在tomcat 8.5 JFinal 3.5 下项目启动运行没有问题，等待一段时间后，就会一直弹出一段警告。

十一月 07, 2018 11:46:15 上午 org.apache.catalina.core.StandardContext reload

信息: Reloading Context with name [/jfinal_demo] has started

十一月 07, 2018 11:46:15 上午 org.apache.catalina.loader.WebappClassLoaderBase clearReferencesJdbc

警告: The web application [jfinal_demo] registered the JDBC driver [com.alibaba.druid.proxy.DruidDriver] but failed to unregister it when the web application was stopped. To prevent a memory leak, the JDBC Driver has been forcibly unregistered.

十一月 07, 2018 11:46:15 上午 org.apache.catalina.loader.WebappClassLoaderBase clearReferencesJdbc

警告: The web application [jfinal_demo] registered the JDBC driver [com.mysql.jdbc.Driver] but failed to unregister it when the web application was stopped. To prevent a memory leak, the JDBC Driver has been forcibly unregistered.

十一月 07, 2018 11:46:15 上午 org.apache.catalina.loader.WebappClassLoaderBase clearReferencesThreads

警告: The web application [jfinal_demo] appears to have started a thread named [Abandoned connection cleanup thread] but has failed to stop it. This is very likely to create a memory leak. Stack trace of thread:

 java.lang.Object.wait(Native Method)

 java.lang.ref.ReferenceQueue.remove(Unknown Source)

 com.mysql.jdbc.AbandonedConnectionCleanupThread.run(AbandonedConnectionCleanupThread.java:64)

 java.util.concurrent.ThreadPoolExecutor.runWorker(Unknown Source)

 java.util.concurrent.ThreadPoolExecutor$Worker.run(Unknown Source)

 java.lang.Thread.run(Unknown Source)

信息: Illegal access: this web application instance has been stopped already. Could not load []. The following stack trace is thrown for debugging purposes as well as to attempt to terminate the thread which caused the illegal access.

java.lang.IllegalStateException: Illegal access: this web application instance has been stopped already. Could not load []. The following stack trace is thrown for debugging purposes as well as to attempt to terminate the thread which caused the illegal access.

at org.apache.catalina.loader.WebappClassLoaderBase.checkStateForResourceLoading(WebappClassLoaderBase.java:1305)

at org.apache.catalina.loader.WebappClassLoaderBase.getResource(WebappClassLoaderBase.java:986)

at com.mysql.jdbc.AbandonedConnectionCleanupThread.checkContextClassLoaders(AbandonedConnectionCleanupThread.java:90)

at com.mysql.jdbc.AbandonedConnectionCleanupThread.run(AbandonedConnectionCleanupThread.java:63)

at java.util.concurrent.ThreadPoolExecutor.runWorker(Unknown Source)

at java.util.concurrent.ThreadPoolExecutor$Worker.run(Unknown Source)

at java.lang.Thread.run(Unknown Source)