java.lang.IllegalStateException: UT010019: Response already commited

[2019-08-09 14:29:52:145] [WARN][org.springframework.web.servlet.mvc.support.DefaultHandlerExceptionResolver][XNIO-2 task-9] - org.springframework.web.servlet.mvc.support.DefaultHandlerExceptionResolver.doResolveException(DefaultHandlerExceptionResolver.java:234) - Failure while trying to resolve exception [org.springframework.web.HttpMediaTypeNotAcceptableException]
java.lang.IllegalStateException: UT010019: Response already commited
        at io.undertow.servlet.spec.HttpServletResponseImpl.sendError(HttpServletResponseImpl.java:131) ~[undertow-servlet-1.4.26.Final.jar:1.4.26.Final]
        at io.undertow.servlet.spec.HttpServletResponseImpl.sendError(HttpServletResponseImpl.java:178) ~[undertow-servlet-1.4.26.Final.jar:1.4.26.Final]
        at javax.servlet.http.HttpServletResponseWrapper.sendError(HttpServletResponseWrapper.java:167) ~[javax.servlet-api-3.1.0.jar:3.1.0]
        at com.alibaba.druid.support.http.WebStatFilter$StatHttpServletResponseWrapper.sendError(WebStatFilter.java:342) ~[druid-1.1.10.jar:1.1.10]
        at org.springframework.web.servlet.mvc.support.DefaultHandlerExceptionResolver.handleHttpMediaTypeNotAcceptable(DefaultHandlerExceptionResolver.java:304) ~[spring-webmvc-5.0.11.RELEASE.jar:5.0.11.RELEASE]
        at org.springframework.web.servlet.mvc.support.DefaultHandlerExceptionResolver.doResolveException(DefaultHandlerExceptionResolver.java:181) [spring-webmvc-5.0.11.RELEASE.jar:5.0.11.RELEASE]
        at org.springframework.web.servlet.handler.AbstractHandlerExceptionResolver.resolveException(AbstractHandlerExceptionResolver.java:136) [spring-webmvc-5.0.11.RELEASE.jar:5.0.11.RELEASE]
        at org.springframework.web.servlet.handler.HandlerExceptionResolverComposite.resolveException(HandlerExceptionResolverComposite.java:78) [spring-webmvc-5.0.11.RELEASE.jar:5.0.11.RELEASE]
        at org.springframework.web.servlet.DispatcherServlet.processHandlerException(DispatcherServlet.java:1255) [spring-webmvc-5.0.11.RELEASE.jar:5.0.11.RELEASE]
        at org.springframework.web.servlet.DispatcherServlet.processDispatchResult(DispatcherServlet.java:1062) [spring-webmvc-5.0.11.RELEASE.jar:5.0.11.RELEASE]
        at org.springframework.web.servlet.DispatcherServlet.doDispatch(DispatcherServlet.java:1008) [spring-webmvc-5.0.11.RELEASE.jar:5.0.11.RELEASE]
        at org.springframework.web.servlet.DispatcherServlet.doService(DispatcherServlet.java:925) [spring-webmvc-5.0.11.RELEASE.jar:5.0.11.RELEASE]
        at org.springframework.web.servlet.FrameworkServlet.processRequest(FrameworkServlet.java:981) [spring-webmvc-5.0.11.RELEASE.jar:5.0.11.RELEASE]
        at org.springframework.web.servlet.FrameworkServlet.doPost(FrameworkServlet.java:884) [spring-webmvc-5.0.11.RELEASE.jar:5.0.11.RELEASE]
        at javax.servlet.http.HttpServlet.service(HttpServlet.java:707) [javax.servlet-api-3.1.0.jar:3.1.0]
        at org.springframework.web.servlet.FrameworkServlet.service(FrameworkServlet.java:858) [spring-webmvc-5.0.11.RELEASE.jar:5.0.11.RELEASE]
        at javax.servlet.http.HttpServlet.service(HttpServlet.java:790) [javax.servlet-api-3.1.0.jar:3.1.0]
        at io.undertow.servlet.handlers.ServletHandler.handleRequest(ServletHandler.java:74) [undertow-servlet-1.4.26.Final.jar:1.4.26.Final]
        at io.undertow.servlet.handlers.FilterHandler$FilterChainImpl.doFilter(FilterHandler.java:129) [undertow-servlet-1.4.26.Final.jar:1.4.26.Final]
        at io.undertow.websockets.jsr.JsrWebSocketFilter.doFilter(JsrWebSocketFilter.java:173) [undertow-websockets-jsr-1.4.26.Final.jar:1.4.26.Final]
        at io.undertow.servlet.core.ManagedFilter.doFilter(ManagedFilter.java:61) [undertow-servlet-1.4.26.Final.jar:1.4.26.Final]
        at io.undertow.servlet.handlers.FilterHandler$FilterChainImpl.doFilter(FilterHandler.java:131) [undertow-servlet-1.4.26.Final.jar:1.4.26.Final]
        at com.alibaba.druid.support.http.WebStatFilter.doFilter(WebStatFilter.java:123) [druid-1.1.10.jar:1.1.10]
        at io.undertow.servlet.core.ManagedFilter.doFilter(ManagedFilter.java:61) [undertow-servlet-1.4.26.Final.jar:1.4.26.Final]
        at io.undertow.servlet.handlers.FilterHandler$FilterChainImpl.doFilter(FilterHandler.java:131) [undertow-servlet-1.4.26.Final.jar:1.4.26.Final]
        at org.springframework.boot.actuate.web.trace.servlet.HttpTraceFilter.doFilterInternal(HttpTraceFilter.java:90) [spring-boot-actuator-2.0.7.RELEASE.jar:2.0.7.RELEASE]
        at org.springframework.web.filter.OncePerRequestFilter.doFilter(OncePerRequestFilter.java:107) [spring-web-5.0.11.RELEASE.jar:5.0.11.RELEASE]
        at io.undertow.servlet.core.ManagedFilter.doFilter(ManagedFilter.java:61) [undertow-servlet-1.4.26.Final.jar:1.4.26.Final]
        at io.undertow.servlet.handlers.FilterHandler$FilterChainImpl.doFilter(FilterHandler.java:131) [undertow-servlet-1.4.26.Final.jar:1.4.26.Final]
        at org.springframework.boot.actuate.metrics.web.servlet.WebMvcMetricsFilter.filterAndRecordMetrics(WebMvcMetricsFilter.java:117) [spring-boot-actuator-2.0.7.RELEASE.jar:2.0.7.RELEASE]
        at org.springframework.boot.actuate.metrics.web.servlet.WebMvcMetricsFilter.doFilterInternal(WebMvcMetricsFilter.java:106) [spring-boot-actuator-2.0.7.RELEASE.jar:2.0.7.RELEASE]
        at org.springframework.web.filter.OncePerRequestFilter.doFilter(OncePerRequestFilter.java:107) [spring-web-5.0.11.RELEASE.jar:5.0.11.RELEASE]
        at io.undertow.servlet.core.ManagedFilter.doFilter(ManagedFilter.java:61) [undertow-servlet-1.4.26.Final.jar:1.4.26.Final]
        at io.undertow.servlet.handlers.FilterHandler$FilterChainImpl.doFilter(FilterHandler.java:131) [undertow-servlet-1.4.26.Final.jar:1.4.26.Final]
        at org.springframework.web.filter.CharacterEncodingFilter.doFilterInternal(CharacterEncodingFilter.java:200) [spring-web-5.0.11.RELEASE.jar:5.0.11.RELEASE]
        at org.springframework.web.filter.OncePerRequestFilter.doFilter(OncePerRequestFilter.java:107) [spring-web-5.0.11.RELEASE.jar:5.0.11.RELEASE]
        at io.undertow.servlet.core.ManagedFilter.doFilter(ManagedFilter.java:61) [undertow-servlet-1.4.26.Final.jar:1.4.26.Final]
        at io.undertow.servlet.handlers.FilterHandler$FilterChainImpl.doFilter(FilterHandler.java:131) [undertow-servlet-1.4.26.Final.jar:1.4.26.Final]
        at io.undertow.servlet.handlers.FilterHandler.handleRequest(FilterHandler.java:84) [undertow-servlet-1.4.26.Final.jar:1.4.26.Final]
        at io.undertow.servlet.handlers.security.ServletSecurityRoleHandler.handleRequest(ServletSecurityRoleHandler.java:62) [undertow-servlet-1.4.26.Final.jar:1.4.26.Final]
        at io.undertow.servlet.handlers.ServletChain$1.handleRequest(ServletChain.java:65) [undertow-servlet-1.4.26.Final.jar:1.4.26.Final]
        at io.undertow.servlet.handlers.ServletDispatchingHandler.handleRequest(ServletDispatchingHandler.java:36) [undertow-servlet-1.4.26.Final.jar:1.4.26.Final]
        at io.undertow.servlet.handlers.security.SSLInformationAssociationHandler.handleRequest(SSLInformationAssociationHandler.java:132) [undertow-servlet-1.4.26.Final.jar:1.4.26.Final]
        at io.undertow.servlet.handlers.security.ServletAuthenticationCallHandler.handleRequest(ServletAuthenticationCallHandler.java:57) [undertow-servlet-1.4.26.Final.jar:1.4.26.Final]
        at io.undertow.server.handlers.PredicateHandler.handleRequest(PredicateHandler.java:43) [undertow-core-1.4.26.Final.jar:1.4.26.Final]
        at io.undertow.security.handlers.AbstractConfidentialityHandler.handleRequest(AbstractConfidentialityHandler.java:46) [undertow-core-1.4.26.Final.jar:1.4.26.Final]
        at io.undertow.servlet.handlers.security.ServletConfidentialityConstraintHandler.handleRequest(ServletConfidentialityConstraintHandler.java:64) [undertow-servlet-1.4.26.Final.jar:1.4.26.Final]
        at io.undertow.security.handlers.AuthenticationMechanismsHandler.handleRequest(AuthenticationMechanismsHandler.java:60) [undertow-core-1.4.26.Final.jar:1.4.26.Final]
        at io.undertow.servlet.handlers.security.CachedAuthenticatedSessionHandler.handleRequest(CachedAuthenticatedSessionHandler.java:77) [undertow-servlet-1.4.26.Final.jar:1.4.26.Final]
        at io.undertow.security.handlers.AbstractSecurityContextAssociationHandler.handleRequest(AbstractSecurityContextAssociationHandler.java:43) [undertow-core-1.4.26.Final.jar:1.4.26.Final]
        at io.undertow.server.handlers.PredicateHandler.handleRequest(PredicateHandler.java:43) [undertow-core-1.4.26.Final.jar:1.4.26.Final]
        at io.undertow.server.handlers.PredicateHandler.handleRequest(PredicateHandler.java:43) [undertow-core-1.4.26.Final.jar:1.4.26.Final]
        at io.undertow.servlet.handlers.ServletInitialHandler.handleFirstRequest(ServletInitialHandler.java:292) [undertow-servlet-1.4.26.Final.jar:1.4.26.Final]
        at io.undertow.servlet.handlers.ServletInitialHandler.access$100(ServletInitialHandler.java:81) [undertow-servlet-1.4.26.Final.jar:1.4.26.Final]
        at io.undertow.servlet.handlers.ServletInitialHandler$2.call(ServletInitialHandler.java:138) [undertow-servlet-1.4.26.Final.jar:1.4.26.Final]
        at io.undertow.servlet.handlers.ServletInitialHandler$2.call(ServletInitialHandler.java:135) [undertow-servlet-1.4.26.Final.jar:1.4.26.Final]
        at io.undertow.servlet.core.ServletRequestContextThreadSetupAction$1.call(ServletRequestContextThreadSetupAction.java:48) [undertow-servlet-1.4.26.Final.jar:1.4.26.Final]
        at io.undertow.servlet.core.ContextClassLoaderSetupAction$1.call(ContextClassLoaderSetupAction.java:43) [undertow-servlet-1.4.26.Final.jar:1.4.26.Final]
        at io.undertow.servlet.handlers.ServletInitialHandler.dispatchRequest(ServletInitialHandler.java:272) [undertow-servlet-1.4.26.Final.jar:1.4.26.Final]
        at io.undertow.servlet.handlers.ServletInitialHandler.access$000(ServletInitialHandler.java:81) [undertow-servlet-1.4.26.Final.jar:1.4.26.Final]
        at io.undertow.servlet.handlers.ServletInitialHandler$1.handleRequest(ServletInitialHandler.java:104) [undertow-servlet-1.4.26.Final.jar:1.4.26.Final]
        at io.undertow.server.Connectors.executeRootHandler(Connectors.java:336) [undertow-core-1.4.26.Final.jar:1.4.26.Final]
        at io.undertow.server.HttpServerExchange$1.run(HttpServerExchange.java:830) [undertow-core-1.4.26.Final.jar:1.4.26.Final]
        at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1149) [?:1.8.0_191]
        at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:624) [?:1.8.0_191]
        at java.lang.Thread.run(Thread.java:748) [?:1.8.0_191]

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产生这个原因:在写入文件时调用requestOutputStream.write()方法已将response发出,再在Controller中return时被认为是再发送一次,因而会报错,解决这个问题只需返回null即可。