[MySQL] DAO와 MySQL 연동 에러(Mac, Intellij)

에러 발생

미니 프로젝트로 JSP를 이용하여 만든 미니 프로젝트에 mysql을 연동하는데 계속 아래와 같은 에러 메세지와 함께 오류가 발생했다.

java.lang.ClassNotFoundException: com.mysql.jdbc.Driver
	at org.apache.catalina.loader.WebappClassLoaderBase.loadClass(WebappClassLoaderBase.java:1412)
	at org.apache.catalina.loader.WebappClassLoaderBase.loadClass(WebappClassLoaderBase.java:1220)
	at java.lang.Class.forName0(Native Method)
	at java.lang.Class.forName(Class.java:264)
	at member.MemberDAO.<init>(MemberDAO.java:20)
	at org.apache.jsp.joinAction_jsp._jspService(joinAction_jsp.java:170)
	at org.apache.jasper.runtime.HttpJspBase.service(HttpJspBase.java:70)
	at javax.servlet.http.HttpServlet.service(HttpServlet.java:623)
	at org.apache.jasper.servlet.JspServletWrapper.service(JspServletWrapper.java:466)
	at org.apache.jasper.servlet.JspServlet.serviceJspFile(JspServlet.java:379)
	at org.apache.jasper.servlet.JspServlet.service(JspServlet.java:327)
	at javax.servlet.http.HttpServlet.service(HttpServlet.java:623)
	at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:209)
	at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:153)
	at org.apache.tomcat.websocket.server.WsFilter.doFilter(WsFilter.java:51)
	at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:178)
	at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:153)
	at org.apache.catalina.core.StandardWrapperValve.invoke(StandardWrapperValve.java:168)
	at org.apache.catalina.core.StandardContextValve.invoke(StandardContextValve.java:90)
	at org.apache.catalina.authenticator.AuthenticatorBase.invoke(AuthenticatorBase.java:481)
	at org.apache.catalina.core.StandardHostValve.invoke(StandardHostValve.java:130)
	at org.apache.catalina.valves.ErrorReportValve.invoke(ErrorReportValve.java:93)
	at org.apache.catalina.valves.AbstractAccessLogValve.invoke(AbstractAccessLogValve.java:670)
	at org.apache.catalina.core.StandardEngineValve.invoke(StandardEngineValve.java:74)
	at org.apache.catalina.connector.CoyoteAdapter.service(CoyoteAdapter.java:343)
	at org.apache.coyote.http11.Http11Processor.service(Http11Processor.java:390)
	at org.apache.coyote.AbstractProcessorLight.process(AbstractProcessorLight.java:63)
	at org.apache.coyote.AbstractProtocol$ConnectionHandler.process(AbstractProtocol.java:926)
	at org.apache.tomcat.util.net.NioEndpoint$SocketProcessor.doRun(NioEndpoint.java:1790)
	at org.apache.tomcat.util.net.SocketProcessorBase.run(SocketProcessorBase.java:52)
	at org.apache.tomcat.util.threads.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1191)
	at org.apache.tomcat.util.threads.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:659)
	at org.apache.tomcat.util.threads.TaskThread$WrappingRunnable.run(TaskThread.java:61)
	at java.lang.Thread.run(Thread.java:748)
java.lang.NullPointerException
	at member.MemberDAO.join(MemberDAO.java:49)
	at org.apache.jsp.joinAction_jsp._jspService(joinAction_jsp.java:171)
	at org.apache.jasper.runtime.HttpJspBase.service(HttpJspBase.java:70)
	at javax.servlet.http.HttpServlet.service(HttpServlet.java:623)
	at org.apache.jasper.servlet.JspServletWrapper.service(JspServletWrapper.java:466)
	at org.apache.jasper.servlet.JspServlet.serviceJspFile(JspServlet.java:379)
	at org.apache.jasper.servlet.JspServlet.service(JspServlet.java:327)
	at javax.servlet.http.HttpServlet.service(HttpServlet.java:623)
	at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:209)
	at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:153)
	at org.apache.tomcat.websocket.server.WsFilter.doFilter(WsFilter.java:51)
	at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:178)
	at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:153)
	at org.apache.catalina.core.StandardWrapperValve.invoke(StandardWrapperValve.java:168)
	at org.apache.catalina.core.StandardContextValve.invoke(StandardContextValve.java:90)
	at org.apache.catalina.authenticator.AuthenticatorBase.invoke(AuthenticatorBase.java:481)
	at org.apache.catalina.core.StandardHostValve.invoke(StandardHostValve.java:130)
	at org.apache.catalina.valves.ErrorReportValve.invoke(ErrorReportValve.java:93)
	at org.apache.catalina.valves.AbstractAccessLogValve.invoke(AbstractAccessLogValve.java:670)
	at org.apache.catalina.core.StandardEngineValve.invoke(StandardEngineValve.java:74)
	at org.apache.catalina.connector.CoyoteAdapter.service(CoyoteAdapter.java:343)
	at org.apache.coyote.http11.Http11Processor.service(Http11Processor.java:390)
	at org.apache.coyote.AbstractProcessorLight.process(AbstractProcessorLight.java:63)
	at org.apache.coyote.AbstractProtocol$ConnectionHandler.process(AbstractProtocol.java:926)
	at org.apache.tomcat.util.net.NioEndpoint$SocketProcessor.doRun(NioEndpoint.java:1790)
	at org.apache.tomcat.util.net.SocketProcessorBase.run(SocketProcessorBase.java:52)
	at org.apache.tomcat.util.threads.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1191)
	at org.apache.tomcat.util.threads.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:659)
	at org.apache.tomcat.util.threads.TaskThread$WrappingRunnable.run(TaskThread.java:61)
	at java.lang.Thread.run(Thread.java:748)
14-Sep-2023 16:21:54.947 정보 [Catalina-utility-1] org.apache.catalina.startup.HostConfig.deployDirectory 웹 애플리케이션 디렉토리 [/Users/prao/Desktop/DEV.PRAO/STUDY/TOMCAT/apache-tomcat-9.0.80/webapps/manager]을(를) 배치합니다.
14-Sep-2023 16:21:54.989 정보 [Catalina-utility-1] org.apache.catalina.startup.HostConfig.deployDirectory 웹 애플리케이션 디렉토리 [/Users/prao/Desktop/DEV.PRAO/STUDY/TOMCAT/apache-tomcat-9.0.80/webapps/manager]에 대한 배치가 [41] 밀리초에 완료되었습니다.

정확한 원인은 무엇인지 모르겠으나 com.mysql.jdbc.Driver에 연결이 제대로 되지 않았다는 것은 확실하다.

 

원인

mysql-connector-j-8.1.0.jar 파일을 WEB-INF에 넣어뒀는데,

connector가 제대로 동작하게 하려면 WEB-INF/lib 에 넣어야 하는 것이었다.

따라서 lib 디렉토리를 만들어주고 connector의 위치를 옮기니 제대로 동작하였다.

 

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참고자료

https://velog.io/@hans4257/jsp-MySQL-%EC%97%B0%EB%8F%99-%EC%98%A4%EB%A5%98java.lang.ClassNotFoundException-com.mysql.jdbc.Driver

[jsp] MySQL 연동 오류(java.lang.ClassNotFoundException: com.mysql.jdbc.Driver)