java.lang.NullPointerException에러

Question

&#64;Controller &#64;EnableAsync public class MailController { &#64;Autowired private MailService mailService; // 가상주소 http://localhost:8080/myweb2/sendMail get &#64;RequestMapping(value &#61; &#34;/member/sendMail&#34;, method &#61; RequestMethod.GET) public ModelAndView sendSimpleMail(&#64;RequestParam Map<String, String> receiverMap, HttpServletRequest request, HttpServletResponse response) throws Exception{ System.out.println(&#34;sendMail get&#34;); String viewName&#61;(String)request.getAttribute(&#34;viewName&#34;); ModelAndView mav &#61; new ModelAndView(viewName); System.out.println(&#34;viewName : &#34; &#43; viewName &#43; &#34;, mav : &#34; &#43; mav); // viewName과 mav가 값을 가져오지못합니다 ㅜ request.setCharacterEncoding(&#34;utf-8&#34;); response.setContentType(&#34;text/html;charset&#61;utf-8&#34;); HttpSession session &#61; request.getSession(); MemberBean members &#61;(MemberBean) session.getAttribute(&#34;mb&#34;); System.out.println(&#34;session : &#34; &#43; session &#43; &#34;, members : &#34; &#43; members); //session은 값을 가져오는데 members는 값을 가져오지못합니다 .. String id &#61; members.getId(); String name &#61; members.getName(); String email &#61; members.getEmail(); MemberBean membersBean &#61;(MemberBean) session.getAttribute(&#34;mb&#34;); System.out.println(&#34;membersBean : &#34; &#43; membersBean); mailService.sendMail(membersBean); return mav; } }// viewName과 mav가 값을 가져오지못합니다 ㅜ //session은 값을 가져오는데 members는 값을 가져오지못합니다 .. 아래는 콘솔에러코드입니다 ㅜ 심각: 경로 [/_200217myweb]의 컨텍스트 내의 서블릿 [appServlet]을(를) 위한 Servlet.service() 호출이, 근본 원인(root cause)과 함께, 예외 [Request processing failed; nested exception is java.lang.NullPointerException]을(를) 발생시켰습니다. java.lang.NullPointerException at com.itwillbs._200217controller.MailController.sendSimpleMail(MailController.java:42) at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method) at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62) at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43) at java.lang.reflect.Method.invoke(Method.java:498) at org.springframework.web.method.support.InvocableHandlerMethod.doInvoke(InvocableHandlerMethod.java:221) at org.springframework.web.method.support.InvocableHandlerMethod.invokeForRequest(InvocableHandlerMethod.java:137) at org.springframework.web.servlet.mvc.method.annotation.ServletInvocableHandlerMethod.invokeAndHandle(ServletInvocableHandlerMethod.java:110) at org.springframework.web.servlet.mvc.method.annotation.RequestMappingHandlerAdapter.invokeHandleMethod(RequestMappingHandlerAdapter.java:776) at org.springframework.web.servlet.mvc.method.annotation.RequestMappingHandlerAdapter.handleInternal(RequestMappingHandlerAdapter.java:705) at org.springframework.web.servlet.mvc.method.AbstractHandlerMethodAdapter.handle(AbstractHandlerMethodAdapter.java:85) at org.springframework.web.servlet.DispatcherServlet.doDispatch(DispatcherServlet.java:959) at org.springframework.web.servlet.DispatcherServlet.doService(DispatcherServlet.java:893) at org.springframework.web.servlet.FrameworkServlet.processRequest(FrameworkServlet.java:967) at org.springframework.web.servlet.FrameworkServlet.doGet(FrameworkServlet.java:858) at javax.servlet.http.HttpServlet.service(HttpServlet.java:634) at org.springframework.web.servlet.FrameworkServlet.service(FrameworkServlet.java:843) at javax.servlet.http.HttpServlet.service(HttpServlet.java:741) at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:231) at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:166) at org.apache.tomcat.websocket.server.WsFilter.doFilter(WsFilter.java:52) at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:193) at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:166) at org.springframework.web.filter.CharacterEncodingFilter.doFilterInternal(CharacterEncodingFilter.java:85) at org.springframework.web.filter.OncePerRequestFilter.doFilter(OncePerRequestFilter.java:107) at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:193) at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:166) at org.apache.catalina.core.StandardWrapperValve.invoke(StandardWrapperValve.java:199) at org.apache.catalina.core.StandardContextValve.invoke(StandardContextValve.java:96) at org.apache.catalina.authenticator.AuthenticatorBase.invoke(AuthenticatorBase.java:543) at org.apache.catalina.core.StandardHostValve.invoke(StandardHostValve.java:139) at org.apache.catalina.valves.ErrorReportValve.invoke(ErrorReportValve.java:81) at org.apache.catalina.valves.AbstractAccessLogValve.invoke(AbstractAccessLogValve.java:678) at org.apache.catalina.core.StandardEngineValve.invoke(StandardEngineValve.java:87) at org.apache.catalina.connector.CoyoteAdapter.service(CoyoteAdapter.java:343) at org.apache.coyote.http11.Http11Processor.service(Http11Processor.java:609) at org.apache.coyote.AbstractProcessorLight.process(AbstractProcessorLight.java:65) at org.apache.coyote.AbstractProtocol$ConnectionHandler.process(AbstractProtocol.java:810) at org.apache.tomcat.util.net.NioEndpoint$SocketProcessor.doRun(NioEndpoint.java:1623) at org.apache.tomcat.util.net.SocketProcessorBase.run(SocketProcessorBase.java:49) at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1149) at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:624) at org.apache.tomcat.util.threads.TaskThread$WrappingRunnable.run(TaskThread.java:61) at java.lang.Thread.run(Thread.java:748)MemberBean members &#61;(MemberBean) session.getAttribute(&#34;mb&#34;); 이렇게하면 값을 가져와야하는게아닌가요 ? ㅜ 왜 못가져오는지 이해가 잘 안되네요 ㅜㅜ

방관 · Answer

session 값이 null 인지, null이 아니라면 session.getAttribute(&#34;mb&#34;)이 null 인지 확인해보세요

케이트 · Answer

HttpSession session &#61; request.getSession(); MemberBean members &#61;(MemberBean) session.getAttribute(&#34;mb&#34;); 위의 코드로 입력해서 출력해보니 아래처럼 나와요.. session : org.apache.catalina.session.StandardSessionFacade&#64;1bd4c5ac, members : null 그럼 session 은 불러오는데 session.getAttribute(&#34;mb&#34;)는 null 이라 mb를 못가져오는거같아요 ㅜ 그런데 선언까지해준거같은데 왜안가져오는지 이해가안되네요 ㅜ

방관 · Answer

session.setAttribute(&#34;mb&#34;, true);이런식으로 값은 넣어주셨다는 말씀이시죠? 디버그 모드 통해서 값을 넣을 때 잘 들어가나 한번 보시고값을 뺄 때 선언된 세션에 mb가 존재하는지 확인해보시면 어디가 문제인지 확실히 알 수 있으실거같아요

케이트 · Answer

답변 감사합니다!

java.lang.NullPointerException에러

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