前言：部分参考自网上，侵删。
1、问题描述
启动tomcat部署项目时，报This is very likely to create a memory leak. Stack trace of thread错误。
29-May-2018 12:30:09.322 SEVERE [localhost-startStop-1] org.apache.catalina.core.StandardContext.startInternal One or more Filters failed to start. Full details will be found in the appropriate container log file
29-May-2018 12:30:09.323 SEVERE [localhost-startStop-1] org.apache.catalina.core.StandardContext.startInternal Context [] startup failed due to previous errors
29-May-2018 12:30:09.427 WARNING [localhost-startStop-1] org.apache.catalina.loader.WebappClassLoaderBase.clearReferencesJdbc The web application [ROOT] 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.
29-May-2018 12:30:09.427 WARNING [localhost-startStop-1] org.apache.catalina.loader.WebappClassLoaderBase.clearReferencesJdbc The web application [ROOT] 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.
29-May-2018 12:30:09.428 WARNING [localhost-startStop-1] org.apache.catalina.loader.WebappClassLoaderBase.clearReferencesJdbc The web application [ROOT] registered the JDBC driver [org.h2.Driver] but failed to unregister it when the web application was stopped. To prevent a memory leak, the JDBC Driver has been forcibly unregistered.
29-May-2018 12:30:09.428 WARNING [localhost-startStop-1] org.apache.catalina.loader.WebappClassLoaderBase.clearReferencesThreads The web application [ROOT] 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(ReferenceQueue.java:143)
com.mysql.jdbc.AbandonedConnectionCleanupThread.run(AbandonedConnectionCleanupThread.java:64)
java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1142)
java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:617)
java.lang.Thread.run(Thread.java:745)
2、问题原因
tomcat启动奔溃，同时释放了jdbc连接。
3、解决方案
这种异常造成的原因千奇百怪，并没有统一的处理方案。我主要两个原因：
1.spring-context.xml中引入的bean,没有被成功加载。
2.Mapper.xml出现错误，导致parse失败，比如，generate时，mapper内容重复，或dto,dao等位置不对。