运行时是正常的，但每次redeploy时都报这种信息，也不知道哪里错了（mysql的jar包已经引入了）

严重: The web application [/javaliker] 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.
九月 05, 2016 6:30:34 下午 org.apache.catalina.loader.WebappClassLoader clearReferencesThreads
严重: The web application [/javaliker] appears to have started a thread named [Timer-0] but has failed to stop it. This is very likely to create a memory leak.
九月 05, 2016 6:30:34 下午 org.apache.catalina.loader.WebappClassLoader clearReferencesThreads
严重: The web application [/javaliker] appears to have started a thread named [MySQL Statement Cancellation Timer] but has failed to stop it. This is very likely to create a memory leak.