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java.lang.NullPointerException: Cannot invoke "Package.Class.Method" because "this.Class" is null

해결 : 

윈도우10 환경에서 lsnrctl start 명령어 실행 시 에러내용

Unable to OpenSCManager: err=5

해결 : 

cmd(명령 프롬프트)창을 마우스 우클릭 하고 관리자 권한으로 실행한 뒤 lsnrctl start 실행

심각: Error configuring application listener of class [org.springframework.web.context.ContextLoaderListener]
java.lang.ClassNotFoundException: org.springframework.web.context.ContextLoaderListener
at org.apache.catalina.loader.WebappClassLoaderBase.loadClass(WebappClassLoaderBase.java:1360)
at org.apache.catalina.loader.WebappClassLoaderBase.loadClass(WebappClassLoaderBase.java:1182)
at org.apache.catalina.core.DefaultInstanceManager.loadClass(DefaultInstanceManager.java:546)
at org.apache.catalina.core.DefaultInstanceManager.loadClassMaybePrivileged(DefaultInstanceManager.java:527)
at org.apache.catalina.core.DefaultInstanceManager.newInstance(DefaultInstanceManager.java:150)
at org.apache.catalina.core.StandardContext.listenerStart(StandardContext.java:4621)
at org.apache.catalina.core.StandardContext.startInternal(StandardContext.java:5165)
at org.apache.catalina.util.LifecycleBase.start(LifecycleBase.java:150)
at org.apache.catalina.core.ContainerBase$StartChild.call(ContainerBase.java:1412)
at org.apache.catalina.core.ContainerBase$StartChild.call(ContainerBase.java:1402)
at java.util.concurrent.FutureTask.run(Unknown Source)
at java.util.concurrent.ThreadPoolExecutor.runWorker(Unknown Source)
at java.util.concurrent.ThreadPoolExecutor$Worker.run(Unknown Source)
at java.lang.Thread.run(Unknown Source)

해결 : 

Project > 우클릭 > properties > Deployment Assembly > Add > Java Build Path Entries > Finish

오류 사항 :

The type org.springframework.dao.support.DaoSupport cannot be resolved. It is indirectly referenced from required .class files

해결 방법 :

라이브러리의 문제이다.

spring.jar 라이브러리를 추가 해주면 됩니다.

위치는 /WEB-INF/lib에 추가해주면 됩니다.