Java 在这种情况下，为什么Tomcat无法从WEB-INF/lib加载类？
我的应用程序使用Java 在这种情况下，为什么Tomcat无法从WEB-INF/lib加载类？,java,spring-security,jackson,classloader,tomcat8,Java,Spring Security,Jackson,Classloader,Tomcat8,我的应用程序使用jjwt生成jwt令牌。jjwt反过来使用jackson。我的WEB-INF/lib文件夹包含jackson-core-2.8.10.jar，我已验证该文件夹包含JsonProcessingException类文件。但当我到达代码中的特定点时，我得到： java.lang.NoClassDefFoundError:com/fasterxml/jackson/core/JsonProcessingException 更奇怪的是，当我的朋友在Windows（我使用的是Linux）上以
jjwtjackson-core-2.8.10.jarJsonProcessingExceptionString jwt_token = Jwts.builder()
.setClaims(claims)
.signWith(SignatureAlgorithm.HS512, environment.getRequiredProperty("jwt.secret.key"))
.compact();
2017-10-26 05:23:22.110 ERROR 7422 --- [nio-8080-exec-2] o.s.boot.web.support.ErrorPageFilter : Forwarding to error page from request [/token] due to exception [com/fasterxml/jackson/core/JsonProcessingException]
java.lang.NoClassDefFoundError: com/fasterxml/jackson/core/JsonProcessingException
at io.jsonwebtoken.Jwts.builder(Jwts.java:116) ~[jjwt-0.8.0.jar:0.8.0]
at com.myapp.rest.security.JwtGenerator.generate(JwtGenerator.java:58) ~[classes/:na]
at com.myapp.rest.controller.JwtTokenController.generateJwt(JwtTokenController.java:40) ~[classes/:na]
at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method) ~[na:1.8.0_151]
at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62) ~[na:1.8.0_151]
at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43) ~[na:1.8.0_151]
at java.lang.reflect.Method.invoke(Method.java:498) ~[na:1.8.0_151]
at org.springframework.web.method.support.InvocableHandlerMethod.doInvoke(InvocableHandlerMethod.java:205) ~[spring-web-4.3.12.RELEASE.jar:4.3.12.RELEASE]
at org.springframework.web.method.support.InvocableHandlerMethod.invokeForRequest(InvocableHandlerMethod.java:133) ~[spring-web-4.3.12.RELEASE.jar:4.3.12.RELEASE]
at org.springframework.web.servlet.mvc.method.annotation.ServletInvocableHandlerMethod.invokeAndHandle(ServletInvocableHandlerMethod.java:97) ~[spring-webmvc-4.3.12.RELEASE.jar:4.3.12.RELEASE]
at org.springframework.web.servlet.mvc.method.annotation.RequestMappingHandlerAdapter.invokeHandlerMethod(RequestMappingHandlerAdapter.java:827) ~[spring-webmvc-4.3.12.RELEASE.jar:4.3.12.RELEASE]
at org.springframework.web.servlet.mvc.method.annotation.RequestMappingHandlerAdapter.handleInternal(RequestMappingHandlerAdapter.java:738) ~[spring-webmvc-4.3.12.RELEASE.jar:4.3.12.RELEASE]
at org.springframework.web.servlet.mvc.method.AbstractHandlerMethodAdapter.handle(AbstractHandlerMethodAdapter.java:85) ~[spring-webmvc-4.3.12.RELEASE.jar:4.3.12.RELEASE]
at org.springframework.web.servlet.DispatcherServlet.doDispatch(DispatcherServlet.java:967) ~[spring-webmvc-4.3.12.RELEASE.jar:4.3.12.RELEASE]
at org.springframework.web.servlet.DispatcherServlet.doService(DispatcherServlet.java:901) ~[spring-webmvc-4.3.12.RELEASE.jar:4.3.12.RELEASE]
at org.springframework.web.servlet.FrameworkServlet.processRequest(FrameworkServlet.java:970) ~[spring-webmvc-4.3.12.RELEASE.jar:4.3.12.RELEASE]
at org.springframework.web.servlet.FrameworkServlet.doPost(FrameworkServlet.java:872) ~[spring-webmvc-4.3.12.RELEASE.jar:4.3.12.RELEASE]
at javax.servlet.http.HttpServlet.service(HttpServlet.java:661) ~[servlet-api.jar:na]
at org.springframework.web.servlet.FrameworkServlet.service(FrameworkServlet.java:846) ~[spring-webmvc-4.3.12.RELEASE.jar:4.3.12.RELEASE]
at javax.servlet.http.HttpServlet.service(HttpServlet.java:742) ~[servlet-api.jar:na]
at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:231) [catalina.jar:8.5.23]
at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:166) [catalina.jar:8.5.23]
at org.apache.tomcat.websocket.server.WsFilter.doFilter(WsFilter.java:52) ~[tomcat-websocket.jar:8.5.23]
at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:193) [catalina.jar:8.5.23]
at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:166) [catalina.jar:8.5.23]
at org.springframework.security.web.authentication.AbstractAuthenticationProcessingFilter.doFilter(AbstractAuthenticationProcessingFilter.java:200) ~[spring-security-web-4.2.3.RELEASE.jar:4.2.3.RELEASE]
at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:193) [catalina.jar:8.5.23]
at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:166) [catalina.jar:8.5.23]
at org.springframework.security.web.FilterChainProxy$VirtualFilterChain.doFilter(FilterChainProxy.java:317) ~[spring-security-web-4.2.3.RELEASE.jar:4.2.3.RELEASE]
at org.springframework.security.web.access.intercept.FilterSecurityInterceptor.invoke(FilterSecurityInterceptor.java:127) ~[spring-security-web-4.2.3.RELEASE.jar:4.2.3.RELEASE]
at org.springframework.security.web.access.intercept.FilterSecurityInterceptor.doFilter(FilterSecurityInterceptor.java:91) ~[spring-security-web-4.2.3.RELEASE.jar:4.2.3.RELEASE]
at org.springframework.security.web.FilterChainProxy$VirtualFilterChain.doFilter(FilterChainProxy.java:331) ~[spring-security-web-4.2.3.RELEASE.jar:4.2.3.RELEASE]
at org.springframework.security.web.access.ExceptionTranslationFilter.doFilter(ExceptionTranslationFilter.java:114) ~[spring-security-web-4.2.3.RELEASE.jar:4.2.3.RELEASE]
at org.springframework.security.web.FilterChainProxy$VirtualFilterChain.doFilter(FilterChainProxy.java:331) ~[spring-security-web-4.2.3.RELEASE.jar:4.2.3.RELEASE]
at org.springframework.security.web.session.SessionManagementFilter.doFilter(SessionManagementFilter.java:137) ~[spring-security-web-4.2.3.RELEASE.jar:4.2.3.RELEASE]
at org.springframework.security.web.FilterChainProxy$VirtualFilterChain.doFilter(FilterChainProxy.java:331) ~[spring-security-web-4.2.3.RELEASE.jar:4.2.3.RELEASE]
at org.springframework.security.web.authentication.AnonymousAuthenticationFilter.doFilter(AnonymousAuthenticationFilter.java:111) ~[spring-security-web-4.2.3.RELEASE.jar:4.2.3.RELEASE]
at org.springframework.security.web.FilterChainProxy$VirtualFilterChain.doFilter(FilterChainProxy.java:331) ~[spring-security-web-4.2.3.RELEASE.jar:4.2.3.RELEASE]
at org.springframework.security.web.servletapi.SecurityContextHolderAwareRequestFilter.doFilter(SecurityContextHolderAwareRequestFilter.java:170) ~[spring-security-web-4.2.3.RELEASE.jar:4.2.3.RELEASE]
at org.springframework.security.web.FilterChainProxy$VirtualFilterChain.doFilter(FilterChainProxy.java:331) ~[spring-security-web-4.2.3.RELEASE.jar:4.2.3.RELEASE]
at org.springframework.security.web.savedrequest.RequestCacheAwareFilter.doFilter(RequestCacheAwareFilter.java:63) ~[spring-security-web-4.2.3.RELEASE.jar:4.2.3.RELEASE]
at org.springframework.security.web.FilterChainProxy$VirtualFilterChain.doFilter(FilterChainProxy.java:331) ~[spring-security-web-4.2.3.RELEASE.jar:4.2.3.RELEASE]
at org.springframework.security.web.authentication.AbstractAuthenticationProcessingFilter.doFilter(AbstractAuthenticationProcessingFilter.java:200) ~[spring-security-web-4.2.3.RELEASE.jar:4.2.3.RELEASE]
at org.springframework.security.web.FilterChainProxy$VirtualFilterChain.doFilter(FilterChainProxy.java:331) ~[spring-security-web-4.2.3.RELEASE.jar:4.2.3.RELEASE]
at org.springframework.security.web.authentication.logout.LogoutFilter.doFilter(LogoutFilter.java:116) ~[spring-security-web-4.2.3.RELEASE.jar:4.2.3.RELEASE]
at org.springframework.security.web.FilterChainProxy$VirtualFilterChain.doFilter(FilterChainProxy.java:331) ~[spring-security-web-4.2.3.RELEASE.jar:4.2.3.RELEASE]
at org.springframework.web.filter.CorsFilter.doFilterInternal(CorsFilter.java:96) ~[spring-web-4.3.12.RELEASE.jar:4.3.12.RELEASE]
at org.springframework.web.filter.OncePerRequestFilter.doFilter(OncePerRequestFilter.java:107) [spring-web-4.3.12.RELEASE.jar:4.3.12.RELEASE]
at org.springframework.security.web.FilterChainProxy$VirtualFilterChain.doFilter(FilterChainProxy.java:331) ~[spring-security-web-4.2.3.RELEASE.jar:4.2.3.RELEASE]
at org.springframework.security.web.header.HeaderWriterFilter.doFilterInternal(HeaderWriterFilter.java:64) ~[spring-security-web-4.2.3.RELEASE.jar:4.2.3.RELEASE]
at org.springframework.web.filter.OncePerRequestFilter.doFilter(OncePerRequestFilter.java:107) [spring-web-4.3.12.RELEASE.jar:4.3.12.RELEASE]
at org.springframework.security.web.FilterChainProxy$VirtualFilterChain.doFilter(FilterChainProxy.java:331) ~[spring-security-web-4.2.3.RELEASE.jar:4.2.3.RELEASE]
at org.springframework.security.web.context.SecurityContextPersistenceFilter.doFilter(SecurityContextPersistenceFilter.java:105) ~[spring-security-web-4.2.3.RELEASE.jar:4.2.3.RELEASE]
at org.springframework.security.web.FilterChainProxy$VirtualFilterChain.doFilter(FilterChainProxy.java:331) ~[spring-security-web-4.2.3.RELEASE.jar:4.2.3.RELEASE]
at org.springframework.security.web.context.request.async.WebAsyncManagerIntegrationFilter.doFilterInternal(WebAsyncManagerIntegrationFilter.java:56) ~[spring-security-web-4.2.3.RELEASE.jar:4.2.3.RELEASE]
at org.springframework.web.filter.OncePerRequestFilter.doFilter(OncePerRequestFilter.java:107) [spring-web-4.3.12.RELEASE.jar:4.3.12.RELEASE]
at org.springframework.security.web.FilterChainProxy$VirtualFilterChain.doFilter(FilterChainProxy.java:331) ~[spring-security-web-4.2.3.RELEASE.jar:4.2.3.RELEASE]
at org.springframework.security.web.FilterChainProxy.doFilterInternal(FilterChainProxy.java:214) ~[spring-security-web-4.2.3.RELEASE.jar:4.2.3.RELEASE]
at org.springframework.security.web.FilterChainProxy.doFilter(FilterChainProxy.java:177) ~[spring-security-web-4.2.3.RELEASE.jar:4.2.3.RELEASE]
at org.springframework.web.filter.DelegatingFilterProxy.invokeDelegate(DelegatingFilterProxy.java:347) ~[spring-web-4.3.12.RELEASE.jar:4.3.12.RELEASE]
at org.springframework.web.filter.DelegatingFilterProxy.doFilter(DelegatingFilterProxy.java:263) ~[spring-web-4.3.12.RELEASE.jar:4.3.12.RELEASE]
at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:193) [catalina.jar:8.5.23]
at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:166) [catalina.jar:8.5.23]
at org.springframework.web.filter.CharacterEncodingFilter.doFilterInternal(CharacterEncodingFilter.java:197) ~[spring-web-4.3.12.RELEASE.jar:4.3.12.RELEASE]
at org.springframework.web.filter.OncePerRequestFilter.doFilter(OncePerRequestFilter.java:107) [spring-web-4.3.12.RELEASE.jar:4.3.12.RELEASE]
at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:193) [catalina.jar:8.5.23]
at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:166) [catalina.jar:8.5.23]
at org.springframework.boot.web.support.ErrorPageFilter.doFilter(ErrorPageFilter.java:115) [spring-boot-1.5.8.RELEASE.jar:1.5.8.RELEASE]
at org.springframework.boot.web.support.ErrorPageFilter.access$000(ErrorPageFilter.java:59) [spring-boot-1.5.8.RELEASE.jar:1.5.8.RELEASE]
at org.springframework.boot.web.support.ErrorPageFilter$1.doFilterInternal(ErrorPageFilter.java:90) [spring-boot-1.5.8.RELEASE.jar:1.5.8.RELEASE]
at org.springframework.web.filter.OncePerRequestFilter.doFilter(OncePerRequestFilter.java:107) [spring-web-4.3.12.RELEASE.jar:4.3.12.RELEASE]
at org.springframework.boot.web.support.ErrorPageFilter.doFilter(ErrorPageFilter.java:108) [spring-boot-1.5.8.RELEASE.jar:1.5.8.RELEASE]
at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:193) [catalina.jar:8.5.23]
at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:166) [catalina.jar:8.5.23]
at org.apache.catalina.core.StandardWrapperValve.invoke(StandardWrapperValve.java:199) [catalina.jar:8.5.23]
at org.apache.catalina.core.StandardContextValve.invoke(StandardContextValve.java:96) [catalina.jar:8.5.23]
at org.apache.catalina.authenticator.AuthenticatorBase.invoke(AuthenticatorBase.java:478) [catalina.jar:8.5.23]
at org.apache.catalina.core.StandardHostValve.invoke(StandardHostValve.java:140) [catalina.jar:8.5.23]
at org.apache.catalina.valves.ErrorReportValve.invoke(ErrorReportValve.java:81) [catalina.jar:8.5.23]
at org.apache.catalina.valves.AbstractAccessLogValve.invoke(AbstractAccessLogValve.java:650) [catalina.jar:8.5.23]
at org.apache.catalina.core.StandardEngineValve.invoke(StandardEngineValve.java:87) [catalina.jar:8.5.23]
at org.apache.catalina.connector.CoyoteAdapter.service(CoyoteAdapter.java:342) [catalina.jar:8.5.23]
at org.apache.coyote.http11.Http11Processor.service(Http11Processor.java:803) [tomcat-coyote.jar:8.5.23]
at org.apache.coyote.AbstractProcessorLight.process(AbstractProcessorLight.java:66) [tomcat-coyote.jar:8.5.23]
at org.apache.coyote.AbstractProtocol$ConnectionHandler.process(AbstractProtocol.java:868) [tomcat-coyote.jar:8.5.23]
at org.apache.tomcat.util.net.NioEndpoint$SocketProcessor.doRun(NioEndpoint.java:1459) [tomcat-coyote.jar:8.5.23]
at org.apache.tomcat.util.net.SocketProcessorBase.run(SocketProcessorBase.java:49) [tomcat-coyote.jar:8.5.23]
at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1149) [na:1.8.0_151]
at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:624) [na:1.8.0_151]
at org.apache.tomcat.util.threads.TaskThread$WrappingRunnable.run(TaskThread.java:61) [tomcat-util.jar:8.5.23]
at java.lang.Thread.run(Thread.java:748) [na:1.8.0_151]
Caused by: java.lang.ClassNotFoundException: com.fasterxml.jackson.core.JsonProcessingException
at java.net.URLClassLoader.findClass(URLClassLoader.java:381) ~[na:1.8.0_151]
at java.lang.ClassLoader.loadClass(ClassLoader.java:424) ~[na:1.8.0_151]
at java.lang.ClassLoader.loadClass(ClassLoader.java:357) ~[na:1.8.0_151]
... 91 common frames omitted
我相信这不是权限问题，因为我也使用超级用户权限运行tomcat，但它仍然会带来问题。我已经重新安装了Tomcat。没用。我对此束手无策。我们的开发过程已经停滞了一个星期，因为我们无法达成一致。我在互联网上搜寻了几十个小时，试图找到一个解决方案，但似乎没有任何效果。任何帮助都将不胜感激。我自己找到了问题的答案。结果是jvm/ext文件夹中有一个jjwt 0.8 jar（我一定是很久以前偶然或有意放置的，没关系）因此，不是从WEB-INF/lib解析jjwt jar，而是在jvm/ext上解析。我以前注意到了这一点，但假设问题与此无关，因为我预期其他jar将在别处找到 事实证明，由于jjwt存在于jvm/ext文件夹中，类加载器在同一文件夹中查找它的依赖项，而没有在其他任何地方查找它，比如WEB-INF/lib
这可能是因为类装入器在层次结构中工作，不同的装入器在不同的级别上查看。此实例中的引导加载程序在jvm/ext中查找类文件。WEB/INF/lib负责加载程序是WebappX加载程序。总之，我删除了jvm/ext中的jar，一切又好了。这个答案为我省去了很多麻烦！我发现自己处于一种类似的情况：servlet的jar被放置在tomcat/lib目录中，但它需要放置在WEB-INF/lib文件夹中的依赖项，并且没有找到它们。当我将servlet移动到WEB-INF/lib时，问题就消失了。即使在阅读了文档之后，我也不能很准确地指出为什么这种依赖关系不能得到解决。。。无论如何，非常感谢您花时间记录您的发现，而不是把它留给自己@罗南：谢谢你的评论。我认为类加载行为真的很奇怪。我们的项目毫无进展，但很高兴看到它有一些积极的结果，因为这副作用持续了3年！