Loading class `com.mysql.jdbc.Driver' The driver is automatically registered via the SPI and manual loading of the driver class is generally unnecessary.

在使用gradle加载jdbc驱动的时候，如果gradle版本过低 会出现以下错误信息，只要升级下gradle版本即可

Loading class `com.mysql.jdbc.Driver'. This is deprecated. The new driver class is `com.mysql.cj.jdbc.Driver'. The driver is automatically registered via the SPI and manual loading of the driver class is generally unnecessary.
20-Dec-2017 19:26:03.968 严重 [RMI TCP Connection(3)-127.0.0.1] org.apache.catalina.core.StandardContext.startInternal One or more listeners failed to start. Full details will be found in the appropriate container log file
20-Dec-2017 19:26:03.969 严重 [RMI TCP Connection(3)-127.0.0.1] org.apache.catalina.core.StandardContext.startInternal Context [] startup failed due to previous errors
20-Dec-2017 19:26:03.993 警告 [RMI TCP Connection(3)-127.0.0.1] org.apache.catalina.loader.WebappClassLoaderBase.clearReferencesJdbc The web application [ROOT] registered the JDBC driver [com.mysql.cj.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.
[2017-12-20 07:26:04,009] Artifact Gradle : com.huajiao : HuajiaoTest.war (exploded): Error during artifact deployment. See server log for details.
20-Dec-2017 19:26:08.324 信息 [Abandoned connection cleanup thread] org.apache.catalina.loader.WebappClassLoaderBase.checkStateForResourceLoading 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:1311)
    at org.apache.catalina.loader.WebappClassLoaderBase.getResource(WebappClassLoaderBase.java:986)
    at com.mysql.cj.jdbc.AbandonedConnectionCleanupThread.checkContextClassLoaders(AbandonedConnectionCleanupThread.java:90)
    at com.mysql.cj.jdbc.AbandonedConnectionCleanupThread.run(AbandonedConnectionCleanupThread.java:63)
    at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1142)
    at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:617)
    at java.lang.Thread.run(Thread.java:745)