Spring 模板分析时出错，无法使用

这个问题本可以有更好的格式，你可以提供更多的细节。无论如何，欢迎来到SO，我知道这是你在这里的第一篇帖子

所以，看起来您有一些在服务器上呈现的模板页面

此模板页面有一个字段

name

，该字段用SPeL表达式“填充”。因此，创建此模板的程序员假定此“名称”可从“呈现上下文”中获得

现在，当您运行流时，出现了一些错误（例如，可能spring security不允许请求继续），但流的基本编写方式是：一方面，当

name

被放到上下文中时，它不会到达该点，另一方面，流处理模板。因此，您有一个错误，它实际上显示在stacktrace中：

2021-03-13 12:05:55.552 ERROR 8932 --- [io-8080-exec-10] org.thymeleaf.TemplateEngine             : [THYMELEAF][http-nio-8080-exec-10] Exception processing template "th_index": An error happened during template parsing (template: "templates/th_index.html")

org.thymeleaf.exceptions.TemplateInputException: An error happened during template parsing (template: "templates/th_index.html")
    at org.thymeleaf.templateparser.markup.AbstractMarkupTemplateParser.parse(AbstractMarkupTemplateParser.java:241) ~[thymeleaf-3.0.12.RELEASE.jar:3.0.12.RELEASE]
    at org.thymeleaf.templateparser.markup.AbstractMarkupTemplateParser.parseStandalone(AbstractMarkupTemplateParser.java:100) ~[thymeleaf-3.0.12.RELEASE.jar:3.0.12.RELEASE]
    at org.thymeleaf.engine.TemplateManager.parseAndProcess(TemplateManager.java:666) ~[thymeleaf-3.0.12.RELEASE.jar:3.0.12.RELEASE]
    at org.thymeleaf.TemplateEngine.process(TemplateEngine.java:1098) [thymeleaf-3.0.12.RELEASE.jar:3.0.12.RELEASE]
    at org.thymeleaf.TemplateEngine.process(TemplateEngine.java:1072) [thymeleaf-3.0.12.RELEASE.jar:3.0.12.RELEASE]
    at org.thymeleaf.spring5.view.ThymeleafView.renderFragment(ThymeleafView.java:366) [thymeleaf-spring5-3.0.12.RELEASE.jar:3.0.12.RELEASE]
    at org.thymeleaf.spring5.view.ThymeleafView.render(ThymeleafView.java:190) [thymeleaf-spring5-3.0.12.RELEASE.jar:3.0.12.RELEASE]
    at org.springframework.web.servlet.DispatcherServlet.render(DispatcherServlet.java:1393) [spring-webmvc-5.3.4.jar:5.3.4]
    at org.springframework.web.servlet.DispatcherServlet.processDispatchResult(DispatcherServlet.java:1138) [spring-webmvc-5.3.4.jar:5.3.4]
    at org.springframework.web.servlet.DispatcherServlet.doDispatch(DispatcherServlet.java:1077) [spring-webmvc-5.3.4.jar:5.3.4]
    at org.springframework.web.servlet.DispatcherServlet.doService(DispatcherServlet.java:962) [spring-webmvc-5.3.4.jar:5.3.4]
    at org.springframework.web.servlet.FrameworkServlet.processRequest(FrameworkServlet.java:1006) [spring-webmvc-5.3.4.jar:5.3.4]
    at org.springframework.web.servlet.FrameworkServlet.doGet(FrameworkServlet.java:898) [spring-webmvc-5.3.4.jar:5.3.4]
    at javax.servlet.http.HttpServlet.service(HttpServlet.java:626) [tomcat-embed-core-9.0.43.jar:4.0.FR]
    at org.springframework.web.servlet.FrameworkServlet.service(FrameworkServlet.java:883) [spring-webmvc-5.3.4.jar:5.3.4]
    at javax.servlet.http.HttpServlet.service(HttpServlet.java:733) [tomcat-embed-core-9.0.43.jar:4.0.FR]
    at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:227) [tomcat-embed-core-9.0.43.jar:9.0.43]
    at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:162) [tomcat-embed-core-9.0.43.jar:9.0.43]
    at org.apache.tomcat.websocket.server.WsFilter.doFilter(WsFilter.java:53) [tomcat-embed-websocket-9.0.43.jar:9.0.43]
    at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:189) [tomcat-embed-core-9.0.43.jar:9.0.43]
    at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:162) [tomcat-embed-core-9.0.43.jar:9.0.43]
    at org.springframework.security.web.FilterChainProxy$VirtualFilterChain.doFilter(FilterChainProxy.java:327) [spring-security-web-5.4.5.jar:5.4.5]
    at org.springframework.security.web.access.intercept.FilterSecurityInterceptor.invoke(FilterSecurityInterceptor.java:115) [spring-security-web-5.4.5.jar:5.4.5]
    at org.springframework.security.web.access.intercept.FilterSecurityInterceptor.doFilter(FilterSecurityInterceptor.java:81) [spring-security-web-5.4.5.jar:5.4.5]
    at org.springframework.security.web.FilterChainProxy$VirtualFilterChain.doFilter(FilterChainProxy.java:336) [spring-security-web-5.4.5.jar:5.4.5]
    at org.springframework.security.web.access.ExceptionTranslationFilter.doFilter(ExceptionTranslationFilter.java:119) [spring-security-web-5.4.5.jar:5.4.5]
    at org.springframework.security.web.access.ExceptionTranslationFilter.doFilter(ExceptionTranslationFilter.java:113) [spring-security-web-5.4.5.jar:5.4.5]
    at org.springframework.security.web.FilterChainProxy$VirtualFilterChain.doFilter(FilterChainProxy.java:336) [spring-security-web-5.4.5.jar:5.4.5]
    at org.springframework.security.web.session.SessionManagementFilter.doFilter(SessionManagementFilter.java:126) [spring-security-web-5.4.5.jar:5.4.5]
    at org.springframework.security.web.session.SessionManagementFilter.doFilter(SessionManagementFilter.java:81) [spring-security-web-5.4.5.jar:5.4.5]
    at org.springframework.security.web.FilterChainProxy$VirtualFilterChain.doFilter(FilterChainProxy.java:336) [spring-security-web-5.4.5.jar:5.4.5]
    at org.springframework.security.web.authentication.AnonymousAuthenticationFilter.doFilter(AnonymousAuthenticationFilter.java:105) [spring-security-web-5.4.5.jar:5.4.5]
    at org.springframework.security.web.FilterChainProxy$VirtualFilterChain.doFilter(FilterChainProxy.java:336) [spring-security-web-5.4.5.jar:5.4.5]
    at org.springframework.security.web.servletapi.SecurityContextHolderAwareRequestFilter.doFilter(SecurityContextHolderAwareRequestFilter.java:149) [spring-security-web-5.4.5.jar:5.4.5]
    at org.springframework.security.web.FilterChainProxy$VirtualFilterChain.doFilter(FilterChainProxy.java:336) [spring-security-web-5.4.5.jar:5.4.5]
    at org.springframework.security.web.savedrequest.RequestCacheAwareFilter.doFilter(RequestCacheAwareFilter.java:63) [spring-security-web-5.4.5.jar:5.4.5]
    at org.springframework.security.web.FilterChainProxy$VirtualFilterChain.doFilter(FilterChainProxy.java:336) [spring-security-web-5.4.5.jar:5.4.5]
    at org.springframework.security.web.authentication.AbstractAuthenticationProcessingFilter.doFilter(AbstractAuthenticationProcessingFilter.java:218) [spring-security-web-5.4.5.jar:5.4.5]
    at org.springframework.security.web.authentication.AbstractAuthenticationProcessingFilter.doFilter(AbstractAuthenticationProcessingFilter.java:212) [spring-security-web-5.4.5.jar:5.4.5]
    at org.springframework.security.web.FilterChainProxy$VirtualFilterChain.doFilter(FilterChainProxy.java:336) [spring-security-web-5.4.5.jar:5.4.5]
    at org.springframework.security.web.authentication.logout.LogoutFilter.doFilter(LogoutFilter.java:103) [spring-security-web-5.4.5.jar:5.4.5]
    at org.springframework.security.web.authentication.logout.LogoutFilter.doFilter(LogoutFilter.java:89) [spring-security-web-5.4.5.jar:5.4.5]
    at org.springframework.security.web.FilterChainProxy$VirtualFilterChain.doFilter(FilterChainProxy.java:336) [spring-security-web-5.4.5.jar:5.4.5]
    at org.springframework.security.web.header.HeaderWriterFilter.doHeadersAfter(HeaderWriterFilter.java:90) [spring-security-web-5.4.5.jar:5.4.5]
    at org.springframework.security.web.header.HeaderWriterFilter.doFilterInternal(HeaderWriterFilter.java:75) [spring-security-web-5.4.5.jar:5.4.5]
    at org.springframework.web.filter.OncePerRequestFilter.doFilter(OncePerRequestFilter.java:119) [spring-web-5.3.4.jar:5.3.4]
    at org.springframework.security.web.FilterChainProxy$VirtualFilterChain.doFilter(FilterChainProxy.java:336) [spring-security-web-5.4.5.jar:5.4.5]
    at org.springframework.security.web.context.SecurityContextPersistenceFilter.doFilter(SecurityContextPersistenceFilter.java:110) [spring-security-web-5.4.5.jar:5.4.5]
    at org.springframework.security.web.context.SecurityContextPersistenceFilter.doFilter(SecurityContextPersistenceFilter.java:80) [spring-security-web-5.4.5.jar:5.4.5]
    at org.springframework.security.web.FilterChainProxy$VirtualFilterChain.doFilter(FilterChainProxy.java:336) [spring-security-web-5.4.5.jar:5.4.5]
    at org.springframework.security.web.context.request.async.WebAsyncManagerIntegrationFilter.doFilterInternal(WebAsyncManagerIntegrationFilter.java:55) [spring-security-web-5.4.5.jar:5.4.5]
    at org.springframework.web.filter.OncePerRequestFilter.doFilter(OncePerRequestFilter.java:119) [spring-web-5.3.4.jar:5.3.4]
    at org.springframework.security.web.FilterChainProxy$VirtualFilterChain.doFilter(FilterChainProxy.java:336) [spring-security-web-5.4.5.jar:5.4.5]
    at org.springframework.security.web.FilterChainProxy.doFilterInternal(FilterChainProxy.java:211) [spring-security-web-5.4.5.jar:5.4.5]
    at org.springframework.security.web.FilterChainProxy.doFilter(FilterChainProxy.java:183) [spring-security-web-5.4.5.jar:5.4.5]
    at org.springframework.web.filter.DelegatingFilterProxy.invokeDelegate(DelegatingFilterProxy.java:358) [spring-web-5.3.4.jar:5.3.4]
    at org.springframework.web.filter.DelegatingFilterProxy.doFilter(DelegatingFilterProxy.java:271) [spring-web-5.3.4.jar:5.3.4]
    at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:189) [tomcat-embed-core-9.0.43.jar:9.0.43]
    at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:162) [tomcat-embed-core-9.0.43.jar:9.0.43]
    at org.springframework.web.filter.RequestContextFilter.doFilterInternal(RequestContextFilter.java:100) [spring-web-5.3.4.jar:5.3.4]
    at org.springframework.web.filter.OncePerRequestFilter.doFilter(OncePerRequestFilter.java:119) [spring-web-5.3.4.jar:5.3.4]
    at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:189) [tomcat-embed-core-9.0.43.jar:9.0.43]
    at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:162) [tomcat-embed-core-9.0.43.jar:9.0.43]
    at org.springframework.web.filter.FormContentFilter.doFilterInternal(FormContentFilter.java:93) [spring-web-5.3.4.jar:5.3.4]
    at org.springframework.web.filter.OncePerRequestFilter.doFilter(OncePerRequestFilter.java:119) [spring-web-5.3.4.jar:5.3.4]
    at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:189) [tomcat-embed-core-9.0.43.jar:9.0.43]
    at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:162) [tomcat-embed-core-9.0.43.jar:9.0.43]
    at org.springframework.web.filter.CharacterEncodingFilter.doFilterInternal(CharacterEncodingFilter.java:201) [spring-web-5.3.4.jar:5.3.4]
    at org.springframework.web.filter.OncePerRequestFilter.doFilter(OncePerRequestFilter.java:119) [spring-web-5.3.4.jar:5.3.4]
    at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:189) [tomcat-embed-core-9.0.43.jar:9.0.43]
    at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:162) [tomcat-embed-core-9.0.43.jar:9.0.43]
    at org.apache.catalina.core.StandardWrapperValve.invoke(StandardWrapperValve.java:202) [tomcat-embed-core-9.0.43.jar:9.0.43]
    at org.apache.catalina.core.StandardContextValve.invoke(StandardContextValve.java:97) [tomcat-embed-core-9.0.43.jar:9.0.43]
    at org.apache.catalina.authenticator.AuthenticatorBase.invoke(AuthenticatorBase.java:542) [tomcat-embed-core-9.0.43.jar:9.0.43]
    at org.apache.catalina.core.StandardHostValve.invoke(StandardHostValve.java:143) [tomcat-embed-core-9.0.43.jar:9.0.43]
    at org.apache.catalina.valves.ErrorReportValve.invoke(ErrorReportValve.java:92) [tomcat-embed-core-9.0.43.jar:9.0.43]
    at org.apache.catalina.core.StandardEngineValve.invoke(StandardEngineValve.java:78) [tomcat-embed-core-9.0.43.jar:9.0.43]
    at org.apache.catalina.connector.CoyoteAdapter.service(CoyoteAdapter.java:346) [tomcat-embed-core-9.0.43.jar:9.0.43]
    at org.apache.coyote.http11.Http11Processor.service(Http11Processor.java:374) [tomcat-embed-core-9.0.43.jar:9.0.43]
    at org.apache.coyote.AbstractProcessorLight.process(AbstractProcessorLight.java:65) [tomcat-embed-core-9.0.43.jar:9.0.43]
    at org.apache.coyote.AbstractProtocol$ConnectionHandler.process(AbstractProtocol.java:887) [tomcat-embed-core-9.0.43.jar:9.0.43]
    at org.apache.tomcat.util.net.NioEndpoint$SocketProcessor.doRun(NioEndpoint.java:1684) [tomcat-embed-core-9.0.43.jar:9.0.43]
    at org.apache.tomcat.util.net.SocketProcessorBase.run(SocketProcessorBase.java:49) [tomcat-embed-core-9.0.43.jar:9.0.43]
    at java.util.concurrent.ThreadPoolExecutor.runWorker(Unknown Source) [na:1.8.0_261]
    at java.util.concurrent.ThreadPoolExecutor$Worker.run(Unknown Source) [na:1.8.0_261]
    at org.apache.tomcat.util.threads.TaskThread$WrappingRunnable.run(TaskThread.java:61) [tomcat-embed-core-9.0.43.jar:9.0.43]
    at java.lang.Thread.run(Unknown Source) [na:1.8.0_261]
Caused by: org.attoparser.ParseException: Exception evaluating SpringEL expression: "#request.userPrincipal.name" (template: "/_header" - line 10, col 45)
    at org.attoparser.MarkupParser.parseDocument(MarkupParser.java:393) ~[attoparser-2.0.5.RELEASE.jar:2.0.5.RELEASE]
    at org.attoparser.MarkupParser.parse(MarkupParser.java:257) ~[attoparser-2.0.5.RELEASE.jar:2.0.5.RELEASE]
    at org.thymeleaf.templateparser.markup.AbstractMarkupTemplateParser.parse(AbstractMarkupTemplateParser.java:230) ~[thymeleaf-3.0.12.RELEASE.jar:3.0.12.RELEASE]
    ... 86 common frames omitted
Caused by: org.thymeleaf.exceptions.TemplateProcessingException: Exception evaluating SpringEL expression: "#request.userPrincipal.name" (template: "/_header" - line 10, col 45)
    at org.thymeleaf.spring5.expression.SPELVariableExpressionEvaluator.evaluate(SPELVariableExpressionEvaluator.java:292) ~[thymeleaf-spring5-3.0.12.RELEASE.jar:3.0.12.RELEASE]
    at org.thymeleaf.standard.expression.VariableExpression.executeVariableExpression(VariableExpression.java:166) ~[thymeleaf-3.0.12.RELEASE.jar:3.0.12.RELEASE]
    at org.thymeleaf.standard.expression.SimpleExpression.executeSimple(SimpleExpression.java:66) ~[thymeleaf-3.0.12.RELEASE.jar:3.0.12.RELEASE]
    at org.thymeleaf.standard.expression.Expression.execute(Expression.java:109) ~[thymeleaf-3.0.12.RELEASE.jar:3.0.12.RELEASE]
    at org.thymeleaf.standard.expression.Expression.execute(Expression.java:138) ~[thymeleaf-3.0.12.RELEASE.jar:3.0.12.RELEASE]
    at org.thymeleaf.standard.processor.StandardUtextTagProcessor.doProcess(StandardUtextTagProcessor.java:87) ~[thymeleaf-3.0.12.RELEASE.jar:3.0.12.RELEASE]
    at org.thymeleaf.processor.element.AbstractAttributeTagProcessor.doProcess(AbstractAttributeTagProcessor.java:74) ~[thymeleaf-3.0.12.RELEASE.jar:3.0.12.RELEASE]
    at org.thymeleaf.processor.element.AbstractElementTagProcessor.process(AbstractElementTagProcessor.java:95) ~[thymeleaf-3.0.12.RELEASE.jar:3.0.12.RELEASE]
    at org.thymeleaf.util.ProcessorConfigurationUtils$ElementTagProcessorWrapper.process(ProcessorConfigurationUtils.java:633) ~[thymeleaf-3.0.12.RELEASE.jar:3.0.12.RELEASE]
    at org.thymeleaf.engine.ProcessorTemplateHandler.handleOpenElement(ProcessorTemplateHandler.java:1314) ~[thymeleaf-3.0.12.RELEASE.jar:3.0.12.RELEASE]
    at org.thymeleaf.engine.OpenElementTag.beHandled(OpenElementTag.java:205) ~[thymeleaf-3.0.12.RELEASE.jar:3.0.12.RELEASE]
    at org.thymeleaf.engine.Model.process(Model.java:282) ~[thymeleaf-3.0.12.RELEASE.jar:3.0.12.RELEASE]
    at org.thymeleaf.engine.ProcessorTemplateHandler.handleOpenElement(ProcessorTemplateHandler.java:1587) ~[thymeleaf-3.0.12.RELEASE.jar:3.0.12.RELEASE]
    at org.thymeleaf.engine.TemplateHandlerAdapterMarkupHandler.handleOpenElementEnd(TemplateHandlerAdapterMarkupHandler.java:304) ~[thymeleaf-3.0.12.RELEASE.jar:3.0.12.RELEASE]
    at org.thymeleaf.templateparser.markup.InlinedOutputExpressionMarkupHandler$InlineMarkupAdapterPreProcessorHandler.handleOpenElementEnd(InlinedOutputExpressionMarkupHandler.java:278) ~[thymeleaf-3.0.12.RELEASE.jar:3.0.12.RELEASE]
    at org.thymeleaf.standard.inline.OutputExpressionInlinePreProcessorHandler.handleOpenElementEnd(OutputExpressionInlinePreProcessorHandler.java:186) ~[thymeleaf-3.0.12.RELEASE.jar:3.0.12.RELEASE]
    at org.thymeleaf.templateparser.markup.InlinedOutputExpressionMarkupHandler.handleOpenElementEnd(InlinedOutputExpressionMarkupHandler.java:124) ~[thymeleaf-3.0.12.RELEASE.jar:3.0.12.RELEASE]
    at org.attoparser.HtmlElement.handleOpenElementEnd(HtmlElement.java:109) ~[attoparser-2.0.5.RELEASE.jar:2.0.5.RELEASE]
    at org.attoparser.HtmlMarkupHandler.handleOpenElementEnd(HtmlMarkupHandler.java:297) ~[attoparser-2.0.5.RELEASE.jar:2.0.5.RELEASE]
    at org.attoparser.MarkupEventProcessorHandler.handleOpenElementEnd(MarkupEventProcessorHandler.java:402) ~[attoparser-2.0.5.RELEASE.jar:2.0.5.RELEASE]
    at org.attoparser.ParsingElementMarkupUtil.parseOpenElement(ParsingElementMarkupUtil.java:159) ~[attoparser-2.0.5.RELEASE.jar:2.0.5.RELEASE]
    at org.attoparser.MarkupParser.parseBuffer(MarkupParser.java:710) ~[attoparser-2.0.5.RELEASE.jar:2.0.5.RELEASE]
    at org.attoparser.MarkupParser.parseDocument(MarkupParser.java:301) ~[attoparser-2.0.5.RELEASE.jar:2.0.5.RELEASE]
    ... 88 common frames omitted
Caused by: org.springframework.expression.spel.SpelEvaluationException: EL1007E: Property or field 'name' cannot be found on null
    at org.springframework.expression.spel.ast.PropertyOrFieldReference.readProperty(PropertyOrFieldReference.java:213) ~[spring-expression-5.3.4.jar:5.3.4]
    at org.springframework.expression.spel.ast.PropertyOrFieldReference.getValueInternal(PropertyOrFieldReference.java:104) ~[spring-expression-5.3.4.jar:5.3.4]
    at org.springframework.expression.spel.ast.PropertyOrFieldReference.access$000(PropertyOrFieldReference.java:51) ~[spring-expression-5.3.4.jar:5.3.4]
    at org.springframework.expression.spel.ast.PropertyOrFieldReference$AccessorLValue.getValue(PropertyOrFieldReference.java:406) ~[spring-expression-5.3.4.jar:5.3.4]
    at org.springframework.expression.spel.ast.CompoundExpression.getValueInternal(CompoundExpression.java:92) ~[spring-expression-5.3.4.jar:5.3.4]
    at org.springframework.expression.spel.ast.SpelNodeImpl.getValue(SpelNodeImpl.java:112) ~[spring-expression-5.3.4.jar:5.3.4]
    at org.springframework.expression.spel.standard.SpelExpression.getValue(SpelExpression.java:337) ~[spring-expression-5.3.4.jar:5.3.4]
    at org.thymeleaf.spring5.expression.SPELVariableExpressionEvaluator.evaluate(SPELVariableExpressionEvaluator.java:265) ~[thymeleaf-spring5-3.0.12.RELEASE.jar:3.0.12.RELEASE]
    ... 110 common frames omitted

---

堆栈跟踪的重要部分包括：

EL1007E: Property or field 'name' cannot be found on null 

因此，问题在于您的

th_index.html

模板

进一步：

An error happened during template parsing (template: "templates/th_index.html")

以及：

我们可以由此推断，

userPrincipal

为

null

，因此，如果对象为

null

，Thymeleaf无法获取

name

属性的值

如果

userPrincipal

可以是

null

，那么您可以像这样修复此问题：

Property or field 'name' cannot be found on null

如果

userPrincipal

从来就不是

null

的意思，那么您需要弄清楚它为什么是

null

。（可能通过查看控制器或安全配置）

Property or field 'name' cannot be found on null

#request.userPrincipal?.name