空指針異常彈簧

Question

我都從 Spring 啟動應用程序中收到以下錯誤。 這是我的 Controller 類的代碼（控制器中的其他服務正常工作）：

@GetMapping(value="/productListConResponseEntity", produces = MediaType.APPLICATION_JSON_VALUE)
public ResponseEntity<?> productListConResponseEntity(HttpServletRequest req) {
    SampleMessage status = new SampleMessage();
    ProductDTOOut productDTOOut = null;

    try {
        productDTOOut = productService.productListConResponseEntity();
    }catch(Exception e) {
        status.setStatus(Constant.ko);
        status.setMessage(e.getMessage() != null?e.getMessage():e.toString());
    }       
    **-->> ProductController.java:108** new ResponseEntity<ProductDTOOut>(productDTOOut, productDTOOut.getStatus().getHttpStatus(req));
}



WARNING: An illegal reflective access operation has occurred
WARNING: Illegal reflective access by org.springframework.cglib.core.ReflectUtils (file:/C:/Users/Utente/eclipse-workspace/.metadata/.plugins/org.eclipse.wst.server.core/tmp0/wtpwebapps/ProdottiMicroservices/WEB-INF/lib/spring-core-5.2.2.RELEASE.jar) to method java.lang.ClassLoader.defineClass(java.lang.String,byte[],int,int,java.security.ProtectionDomain)
WARNING: Please consider reporting this to the maintainers of org.springframework.cglib.core.ReflectUtils
WARNING: Use --illegal-access=warn to enable warnings of further illegal reflective access operations
WARNING: All illegal access operations will be denied in a future release
2020-03-29 16:58:23.757 ERROR 11596 --- [nio-8082-exec-4] o.s.b.w.servlet.support.ErrorPageFilter  : Forwarding to error page from request [/productListConResponseEntity] due to exception [null]

java.lang.NullPointerException: null
    at com.products.controller.ProductController.productListConResponseEntity(ProductController.java:108) 

--> 重要的控制台消息結束 <--

~[classes/:0.0.1-SNAPSHOT] at java.base/jdk.internal.reflect.NativeMethodAccessorImpl.invoke0(Native Method) ~[na:na] at java.base/jdk.internal.reflect.NativeMethodAccessorImpl.invoke( NativeMethodAccessorImpl.java:62) ~[na:na] 在 java.base/jdk.internal.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43) ~[na:na] 在 java.base/java.lang.reflect。 Method.invoke(Method.java:564) ~[na:na] 在 org.springframework.web.method.support.InvocableHandlerMethod.doInvoke(InvocableHandlerMethod.java:190) ~[spring-web-5.2.2.RELEASE.jar :5.2.2.RELEASE] 在 org.springframework.web.method.support.InvocableHandlerMethod.invokeForRequest(InvocableHandlerMethod.java:138) ~[spring-web-5.2.2.RELEASE.jar:5.2.2.RELEASE] 在 org .springframework.web.servlet.mvc.method.annotation.ServletInvocableHandlerMethod.invokeAndHandle(ServletInvocableHandlerMethod.java:106) ~[spring-webmvc-5.2.2.RELEASE.jar:5.2.2.RELEASE] 在 org.springframework.web。 servlet.mvc.method.annotation.RequestMappingHandlerA dapter.invokeHandlerMethod(RequestMappingHandlerAdapter.java:888) ~[spring-webmvc-5.2.2.RELEASE.jar:5.2.2.RELEASE] 在 org.springframework.web.servlet.mvc.method.annotation.RequestMappingHandlerAdapter.handleInternal(RequestMappingHandlerAdapter) .java:793) ~[spring-webmvc-5.2.2.RELEASE.jar:5.2.2.RELEASE] 在 org.springframework.web.servlet.mvc.method.AbstractHandlerMethodAdapter.handle(AbstractHandlerMethodAdapter.java:87) ~[ spring-webmvc-5.2.2.RELEASE.jar:5.2.2.RELEASE] 在 org.springframework.web.servlet.DispatcherServlet.doDispatch(DispatcherServlet.java:1040) ~[spring-webmvc-5.2.2.RELEASE.jar :5.2.2.RELEASE] 在 org.springframework.web.servlet.DispatcherServlet.doService(DispatcherServlet.java:943) ~[spring-webmvc-5.2.2.RELEASE.jar:5.2.2.RELEASE] 在 org.springframework .web.servlet.FrameworkServlet.processRequest(FrameworkServlet.java:1006) ~[spring-webmvc-5.2.2.RELEASE.jar:5.2.2.RELEASE] 在 org.springframework.web.servlet.FrameworkServlet.doGet(FrameworkServlet. java:898) ~[spring-webmvc- 5.2.2.RELEASE.jar:5.2.2.RELEASE]

        at javax.servlet.http.HttpServlet.service(HttpServlet.java:634) ~[servlet-api.jar:na]
        at org.springframework.web.servlet.FrameworkServlet.service(FrameworkServlet.java:883) ~[spring-webmvc-5.2.2.RELEASE.jar:5.2.2.RELEASE]
        at javax.servlet.http.HttpServlet.service(HttpServlet.java:741) ~[servlet-api.jar:na]
        at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:231) ~[catalina.jar:8.5.53]
        at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:166) ~[catalina.jar:8.5.53]
        at org.apache.tomcat.websocket.server.WsFilter.doFilter(WsFilter.java:52) ~[tomcat-websocket.jar:8.5.53]
        at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:193) ~[catalina.jar:8.5.53]
        at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:166) ~[catalina.jar:8.5.53]
        at org.springframework.web.filter.RequestContextFilter.doFilterInternal(RequestContextFilter.java:100) ~[spring-web-5.2.2.RELEASE.jar:5.2.2.RELEASE]
        at org.springframework.web.filter.OncePerRequestFilter.doFilter(OncePerRequestFilter.java:119) ~[spring-web-5.2.2.RELEASE.jar:5.2.2.RELEASE]
        at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:193) ~[catalina.jar:8.5.53]
        at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:166) ~[catalina.jar:8.5.53]
        at org.springframework.web.filter.FormContentFilter.doFilterInternal(FormContentFilter.java:93) ~[spring-web-5.2.2.RELEASE.jar:5.2.2.RELEASE]
        at org.springframework.web.filter.OncePerRequestFilter.doFilter(OncePerRequestFilter.java:119) ~[spring-web-5.2.2.RELEASE.jar:5.2.2.RELEASE]
        at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:193) ~[catalina.jar:8.5.53]
        at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:166) ~[catalina.jar:8.5.53]
        at org.springframework.boot.web.servlet.support.ErrorPageFilter.doFilter(ErrorPageFilter.java:128) ~[spring-boot-2.2.2.RELEASE.jar:2.2.2.RELEASE]
        at org.springframework.boot.web.servlet.support.ErrorPageFilter.access$000(ErrorPageFilter.java:66) ~[spring-boot-2.2.2.RELEASE.jar:2.2.2.RELEASE]
        at org.springframework.boot.web.servlet.support.ErrorPageFilter$1.doFilterInternal(ErrorPageFilter.java:103) ~[spring-boot-2.2.2.RELEASE.jar:2.2.2.RELEASE]
        at org.springframework.web.filter.OncePerRequestFilter.doFilter(OncePerRequestFilter.java:119) ~[spring-web-5.2.2.RELEASE.jar:5.2.2.RELEASE]
        at org.springframework.boot.web.servlet.support.ErrorPageFilter.doFilter(ErrorPageFilter.java:121) ~[spring-boot-2.2.2.RELEASE.jar:2.2.2.RELEASE]
        at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:193) ~[catalina.jar:8.5.53]
        at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:166) ~[catalina.jar:8.5.53]
        at org.springframework.web.filter.CharacterEncodingFilter.doFilterInternal(CharacterEncodingFilter.java:201) ~[spring-web-5.2.2.RELEASE.jar:5.2.2.RELEASE]
        at org.springframework.web.filter.OncePerRequestFilter.doFilter(OncePerRequestFilter.java:119) ~[spring-web-5.2.2.RELEASE.jar:5.2.2.RELEASE]
        at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:193) ~[catalina.jar:8.5.53]
        at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:166) ~[catalina.jar:8.5.53]
        at org.apache.catalina.core.StandardWrapperValve.invoke(StandardWrapperValve.java:199) ~[catalina.jar:8.5.53]
        at org.apache.catalina.core.StandardContextValve.invoke(StandardContextValve.java:96) ~[catalina.jar:8.5.53]
        at org.apache.catalina.authenticator.AuthenticatorBase.invoke(AuthenticatorBase.java:543) ~[catalina.jar:8.5.53]
        at org.apache.catalina.core.StandardHostValve.invoke(StandardHostValve.java:139) ~[catalina.jar:8.5.53]
        at org.apache.catalina.valves.ErrorReportValve.invoke(ErrorReportValve.java:81) ~[catalina.jar:8.5.53]
        at org.apache.catalina.valves.AbstractAccessLogValve.invoke(AbstractAccessLogValve.java:688) ~[catalina.jar:8.5.53]
        at org.apache.catalina.core.StandardEngineValve.invoke(StandardEngineValve.java:87) ~[catalina.jar:8.5.53]
        at org.apache.catalina.connector.CoyoteAdapter.service(CoyoteAdapter.java:343) ~[catalina.jar:8.5.53]
        at org.apache.coyote.http11.Http11Processor.service(Http11Processor.java:615) ~[tomcat-coyote.jar:8.5.53]
        at org.apache.coyote.AbstractProcessorLight.process(AbstractProcessorLight.java:65) ~[tomcat-coyote.jar:8.5.53]
        at org.apache.coyote.AbstractProtocol$ConnectionHandler.process(AbstractProtocol.java:818) ~[tomcat-coyote.jar:8.5.53]
        at org.apache.tomcat.util.net.NioEndpoint$SocketProcessor.doRun(NioEndpoint.java:1623) ~[tomcat-coyote.jar:8.5.53]
        at org.apache.tomcat.util.net.SocketProcessorBase.run(SocketProcessorBase.java:49) ~[tomcat-coyote.jar:8.5.53]
        at java.base/java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1130) ~[na:na]
        at java.base/java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:630) ~[na:na]
        at org.apache.tomcat.util.threads.TaskThread$WrappingRunnable.run(TaskThread.java:61) ~[tomcat-util.jar:8.5.53]
        at java.base/java.lang.Thread.run(Thread.java:832) ~[na:na]

有人可以幫我嗎？

謝謝你的建議，埃利亞斯。

Answer 1

productDTOOut = productService.productListConResponseEntity();

在退出捕獲部分 productDTOOut null 后拋出異常，因此 productDTOOut.getStatus() 為您提供一個空指針。

new ResponseEntity<ProductDTOOut>(productDTOOut, productDTOOut.getStatus().getHttpStatus(req));