评估 SpringEL 表达式的异常

【问题标题】：Exception evaluating SpringEL expression评估 SpringEL 表达式的异常
【发布时间】：2015-09-02 16:25:36
【问题描述】：

我正在尝试将 thymeleaf 与 spring 一起使用，但在解析以下 header.html 片段时遇到问题：

<!DOCTYPE html>
<html>
<head>
</head>
  <body>
    <div class="navbar navbar-inverse navbar-fixed-top" th:fragment="header">
      <div class="container">
        <div class="navbar-header">
          <button type="button" class="navbar-toggle" data-toggle="collapse" data-target=".nav-collapse">
            <span class="icon-bar"></span>
            <span class="icon-bar"></span>
            <span class="icon-bar"></span>
          </button>
          <a class="navbar-brand" href="#">My project</a>
        </div>
        <div class="navbar-collapse collapse">
          <ul class="nav navbar-nav">
            <li class="active"><a href="#" th:href="@{/}">Home</a></li>
            <li><a href="#" th:href="@{/message}">Messages</a></li>
            <li><a href="#" th:href="@{/task}">Tasks</a></li>
          </ul>
          <ul class="nav navbar-nav navbar-right">
            <li th:if="${#authorization.expression('!isAuthenticated()')}">
              <a href="/signin" th:href="@{/signin}">Sign in</a>
            </li>
            <li th:if="${#authorization.expression('isAuthenticated()')}">
              <a href="/logout" th:href="@{/logout}">Logout</a>
            </li>
          </ul>
        </div>
      </div>
    </div>
  </body>
</html>

尝试解析片段和表达式时返回异常。例外是：

HTTP Status 500 - Request processing failed; nested exception is org.thymeleaf.exceptions.TemplateProcessingException: Exception evaluating SpringEL expression: "#authorization.expression('!isAuthenticated()')" (fragments/header:25)


message Request processing failed; nested exception is org.thymeleaf.exceptions.TemplateProcessingException: Exception evaluating SpringEL expression: "#authorization.expression('!isAuthenticated()')" (fragments/header:25)

description The server encountered an internal error that prevented it from fulfilling this request.

exception

org.springframework.web.util.NestedServletException: Request processing failed; nested exception is org.thymeleaf.exceptions.TemplateProcessingException: Exception evaluating SpringEL expression: "#authorization.expression('!isAuthenticated()')" (fragments/header:25)
    org.springframework.web.servlet.FrameworkServlet.processRequest(FrameworkServlet.java:978)
    org.springframework.web.servlet.FrameworkServlet.doGet(FrameworkServlet.java:857)
    javax.servlet.http.HttpServlet.service(HttpServlet.java:622)
    org.springframework.web.servlet.FrameworkServlet.service(FrameworkServlet.java:842)
    javax.servlet.http.HttpServlet.service(HttpServlet.java:729)
    org.apache.tomcat.websocket.server.WsFilter.doFilter(WsFilter.java:52)
    org.springframework.security.web.FilterChainProxy$VirtualFilterChain.doFilter(FilterChainProxy.java:316)
    org.springframework.security.web.access.intercept.FilterSecurityInterceptor.invoke(FilterSecurityInterceptor.java:126)
    org.springframework.security.web.access.intercept.FilterSecurityInterceptor.doFilter(FilterSecurityInterceptor.java:90)
    org.springframework.security.web.FilterChainProxy$VirtualFilterChain.doFilter(FilterChainProxy.java:330)
    org.springframework.security.web.access.ExceptionTranslationFilter.doFilter(ExceptionTranslationFilter.java:114)
    org.springframework.security.web.FilterChainProxy$VirtualFilterChain.doFilter(FilterChainProxy.java:330)
    org.springframework.security.web.session.SessionManagementFilter.doFilter(SessionManagementFilter.java:122)
    org.springframework.security.web.FilterChainProxy$VirtualFilterChain.doFilter(FilterChainProxy.java:330)
    org.springframework.security.web.authentication.AnonymousAuthenticationFilter.doFilter(AnonymousAuthenticationFilter.java:111)
    org.springframework.security.web.FilterChainProxy$VirtualFilterChain.doFilter(FilterChainProxy.java:330)
    org.springframework.security.web.servletapi.SecurityContextHolderAwareRequestFilter.doFilter(SecurityContextHolderAwareRequestFilter.java:169)
    org.springframework.security.web.FilterChainProxy$VirtualFilterChain.doFilter(FilterChainProxy.java:330)
    org.springframework.security.web.savedrequest.RequestCacheAwareFilter.doFilter(RequestCacheAwareFilter.java:48)
    org.springframework.security.web.FilterChainProxy$VirtualFilterChain.doFilter(FilterChainProxy.java:330)
    org.springframework.security.web.authentication.AbstractAuthenticationProcessingFilter.doFilter(AbstractAuthenticationProcessingFilter.java:205)
    org.springframework.security.web.FilterChainProxy$VirtualFilterChain.doFilter(FilterChainProxy.java:330)
    org.springframework.security.web.authentication.logout.LogoutFilter.doFilter(LogoutFilter.java:120)
    org.springframework.security.web.FilterChainProxy$VirtualFilterChain.doFilter(FilterChainProxy.java:330)
    org.springframework.security.web.csrf.CsrfFilter.doFilterInternal(CsrfFilter.java:96)
    org.springframework.web.filter.OncePerRequestFilter.doFilter(OncePerRequestFilter.java:107)
    org.springframework.security.web.FilterChainProxy$VirtualFilterChain.doFilter(FilterChainProxy.java:330)
    org.springframework.security.web.header.HeaderWriterFilter.doFilterInternal(HeaderWriterFilter.java:64)
    org.springframework.web.filter.OncePerRequestFilter.doFilter(OncePerRequestFilter.java:107)
    org.springframework.security.web.FilterChainProxy$VirtualFilterChain.doFilter(FilterChainProxy.java:330)
    org.springframework.security.web.context.request.async.WebAsyncManagerIntegrationFilter.doFilterInternal(WebAsyncManagerIntegrationFilter.java:53)
    org.springframework.web.filter.OncePerRequestFilter.doFilter(OncePerRequestFilter.java:107)
    org.springframework.security.web.FilterChainProxy$VirtualFilterChain.doFilter(FilterChainProxy.java:330)
    org.springframework.security.web.context.SecurityContextPersistenceFilter.doFilter(SecurityContextPersistenceFilter.java:91)
    org.springframework.security.web.FilterChainProxy$VirtualFilterChain.doFilter(FilterChainProxy.java:330)
    org.springframework.security.web.FilterChainProxy.doFilterInternal(FilterChainProxy.java:213)
    org.springframework.security.web.FilterChainProxy.doFilter(FilterChainProxy.java:176)
    org.springframework.web.filter.DelegatingFilterProxy.invokeDelegate(DelegatingFilterProxy.java:344)
    org.springframework.web.filter.DelegatingFilterProxy.doFilter(DelegatingFilterProxy.java:261)
root cause

org.thymeleaf.exceptions.TemplateProcessingException: Exception evaluating SpringEL expression: "#authorization.expression('!isAuthenticated()')" (fragments/header:25)
    org.thymeleaf.spring4.expression.SpelVariableExpressionEvaluator.evaluate(SpelVariableExpressionEvaluator.java:161)
    org.thymeleaf.standard.expression.VariableExpression.executeVariable(VariableExpression.java:154)
    org.thymeleaf.standard.expression.SimpleExpression.executeSimple(SimpleExpression.java:59)
    org.thymeleaf.standard.expression.Expression.execute(Expression.java:103)
    org.thymeleaf.standard.expression.Expression.execute(Expression.java:133)
    org.thymeleaf.standard.expression.Expression.execute(Expression.java:120)
    org.thymeleaf.standard.processor.attr.AbstractStandardConditionalVisibilityAttrProcessor.isVisible(AbstractStandardConditionalVisibilityAttrProcessor.java:66)
    org.thymeleaf.processor.attr.AbstractConditionalVisibilityAttrProcessor.processAttribute(AbstractConditionalVisibilityAttrProcessor.java:59)
    org.thymeleaf.processor.attr.AbstractAttrProcessor.doProcess(AbstractAttrProcessor.java:87)
    org.thymeleaf.processor.AbstractProcessor.process(AbstractProcessor.java:212)
    org.thymeleaf.dom.Node.applyNextProcessor(Node.java:1017)
    org.thymeleaf.dom.Node.processNode(Node.java:972)
    org.thymeleaf.dom.NestableNode.computeNextChild(NestableNode.java:695)
    org.thymeleaf.dom.NestableNode.doAdditionalProcess(NestableNode.java:668)
    org.thymeleaf.dom.Node.processNode(Node.java:990)
    org.thymeleaf.dom.NestableNode.computeNextChild(NestableNode.java:695)
    org.thymeleaf.dom.NestableNode.doAdditionalProcess(NestableNode.java:668)
    org.thymeleaf.dom.Node.processNode(Node.java:990)
    org.thymeleaf.dom.NestableNode.computeNextChild(NestableNode.java:695)
    org.thymeleaf.dom.NestableNode.doAdditionalProcess(NestableNode.java:668)
    org.thymeleaf.dom.Node.processNode(Node.java:990)
    org.thymeleaf.dom.NestableNode.computeNextChild(NestableNode.java:695)
    org.thymeleaf.dom.NestableNode.doAdditionalProcess(NestableNode.java:668)
    org.thymeleaf.dom.Node.processNode(Node.java:990)
    org.thymeleaf.dom.NestableNode.computeNextChild(NestableNode.java:695)
    org.thymeleaf.dom.NestableNode.doAdditionalProcess(NestableNode.java:668)
    org.thymeleaf.dom.Node.processNode(Node.java:990)
    org.thymeleaf.dom.NestableNode.computeNextChild(NestableNode.java:695)
    org.thymeleaf.dom.NestableNode.doAdditionalProcess(NestableNode.java:668)
    org.thymeleaf.dom.Node.processNode(Node.java:990)
    org.thymeleaf.dom.NestableNode.computeNextChild(NestableNode.java:695)
    org.thymeleaf.dom.NestableNode.doAdditionalProcess(NestableNode.java:668)
    org.thymeleaf.dom.Node.processNode(Node.java:990)
    org.thymeleaf.dom.Document.process(Document.java:93)
    org.thymeleaf.TemplateEngine.process(TemplateEngine.java:1155)
    org.thymeleaf.TemplateEngine.process(TemplateEngine.java:1060)
    org.thymeleaf.TemplateEngine.process(TemplateEngine.java:1011)
    org.thymeleaf.spring4.view.ThymeleafView.renderFragment(ThymeleafView.java:335)
    org.thymeleaf.spring4.view.ThymeleafView.render(ThymeleafView.java:190)
    org.springframework.web.servlet.DispatcherServlet.render(DispatcherServlet.java:1244)
    org.springframework.web.servlet.DispatcherServlet.processDispatchResult(DispatcherServlet.java:1027)
    org.springframework.web.servlet.DispatcherServlet.doDispatch(DispatcherServlet.java:971)
    org.springframework.web.servlet.DispatcherServlet.doService(DispatcherServlet.java:893)
    org.springframework.web.servlet.FrameworkServlet.processRequest(FrameworkServlet.java:966)
    org.springframework.web.servlet.FrameworkServlet.doGet(FrameworkServlet.java:857)
    javax.servlet.http.HttpServlet.service(HttpServlet.java:622)
    org.springframework.web.servlet.FrameworkServlet.service(FrameworkServlet.java:842)
    javax.servlet.http.HttpServlet.service(HttpServlet.java:729)
    org.apache.tomcat.websocket.server.WsFilter.doFilter(WsFilter.java:52)
    org.springframework.security.web.FilterChainProxy$VirtualFilterChain.doFilter(FilterChainProxy.java:316)
    org.springframework.security.web.access.intercept.FilterSecurityInterceptor.invoke(FilterSecurityInterceptor.java:126)
    org.springframework.security.web.access.intercept.FilterSecurityInterceptor.doFilter(FilterSecurityInterceptor.java:90)
    org.springframework.security.web.FilterChainProxy$VirtualFilterChain.doFilter(FilterChainProxy.java:330)
    org.springframework.security.web.access.ExceptionTranslationFilter.doFilter(ExceptionTranslationFilter.java:114)
    org.springframework.security.web.FilterChainProxy$VirtualFilterChain.doFilter(FilterChainProxy.java:330)
    org.springframework.security.web.session.SessionManagementFilter.doFilter(SessionManagementFilter.java:122)
    org.springframework.security.web.FilterChainProxy$VirtualFilterChain.doFilter(FilterChainProxy.java:330)
    org.springframework.security.web.authentication.AnonymousAuthenticationFilter.doFilter(AnonymousAuthenticationFilter.java:111)
    org.springframework.security.web.FilterChainProxy$VirtualFilterChain.doFilter(FilterChainProxy.java:330)
    org.springframework.security.web.servletapi.SecurityContextHolderAwareRequestFilter.doFilter(SecurityContextHolderAwareRequestFilter.java:169)
    org.springframework.security.web.FilterChainProxy$VirtualFilterChain.doFilter(FilterChainProxy.java:330)
    org.springframework.security.web.savedrequest.RequestCacheAwareFilter.doFilter(RequestCacheAwareFilter.java:48)
    org.springframework.security.web.FilterChainProxy$VirtualFilterChain.doFilter(FilterChainProxy.java:330)
    org.springframework.security.web.authentication.AbstractAuthenticationProcessingFilter.doFilter(AbstractAuthenticationProcessingFilter.java:205)
    org.springframework.security.web.FilterChainProxy$VirtualFilterChain.doFilter(FilterChainProxy.java:330)
    org.springframework.security.web.authentication.logout.LogoutFilter.doFilter(LogoutFilter.java:120)
    org.springframework.security.web.FilterChainProxy$VirtualFilterChain.doFilter(FilterChainProxy.java:330)
    org.springframework.security.web.csrf.CsrfFilter.doFilterInternal(CsrfFilter.java:96)
    org.springframework.web.filter.OncePerRequestFilter.doFilter(OncePerRequestFilter.java:107)
    org.springframework.security.web.FilterChainProxy$VirtualFilterChain.doFilter(FilterChainProxy.java:330)
    org.springframework.security.web.header.HeaderWriterFilter.doFilterInternal(HeaderWriterFilter.java:64)
    org.springframework.web.filter.OncePerRequestFilter.doFilter(OncePerRequestFilter.java:107)
    org.springframework.security.web.FilterChainProxy$VirtualFilterChain.doFilter(FilterChainProxy.java:330)
    org.springframework.security.web.context.request.async.WebAsyncManagerIntegrationFilter.doFilterInternal(WebAsyncManagerIntegrationFilter.java:53)
    org.springframework.web.filter.OncePerRequestFilter.doFilter(OncePerRequestFilter.java:107)
    org.springframework.security.web.FilterChainProxy$VirtualFilterChain.doFilter(FilterChainProxy.java:330)
    org.springframework.security.web.context.SecurityContextPersistenceFilter.doFilter(SecurityContextPersistenceFilter.java:91)
    org.springframework.security.web.FilterChainProxy$VirtualFilterChain.doFilter(FilterChainProxy.java:330)
    org.springframework.security.web.FilterChainProxy.doFilterInternal(FilterChainProxy.java:213)
    org.springframework.security.web.FilterChainProxy.doFilter(FilterChainProxy.java:176)
    org.springframework.web.filter.DelegatingFilterProxy.invokeDelegate(DelegatingFilterProxy.java:344)
    org.springframework.web.filter.DelegatingFilterProxy.doFilter(DelegatingFilterProxy.java:261)
root cause

org.springframework.expression.spel.SpelEvaluationException: EL1011E:(pos 15): Method call: Attempted to call method expression(java.lang.String) on null context object
    org.springframework.expression.spel.ast.MethodReference.throwIfNotNullSafe(MethodReference.java:144)
    org.springframework.expression.spel.ast.MethodReference.getValueRef(MethodReference.java:73)
    org.springframework.expression.spel.ast.CompoundExpression.getValueRef(CompoundExpression.java:66)
    org.springframework.expression.spel.ast.CompoundExpression.getValueInternal(CompoundExpression.java:87)
    org.springframework.expression.spel.ast.SpelNodeImpl.getValue(SpelNodeImpl.java:120)
    org.springframework.expression.spel.standard.SpelExpression.getValue(SpelExpression.java:267)
    org.thymeleaf.spring4.expression.SpelVariableExpressionEvaluator.evaluate(SpelVariableExpressionEvaluator.java:139)
    org.thymeleaf.standard.expression.VariableExpression.executeVariable(VariableExpression.java:154)
    org.thymeleaf.standard.expression.SimpleExpression.executeSimple(SimpleExpression.java:59)
    org.thymeleaf.standard.expression.Expression.execute(Expression.java:103)
    org.thymeleaf.standard.expression.Expression.execute(Expression.java:133)
    org.thymeleaf.standard.expression.Expression.execute(Expression.java:120)
    org.thymeleaf.standard.processor.attr.AbstractStandardConditionalVisibilityAttrProcessor.isVisible(AbstractStandardConditionalVisibilityAttrProcessor.java:66)
    org.thymeleaf.processor.attr.AbstractConditionalVisibilityAttrProcessor.processAttribute(AbstractConditionalVisibilityAttrProcessor.java:59)
    org.thymeleaf.processor.attr.AbstractAttrProcessor.doProcess(AbstractAttrProcessor.java:87)
    org.thymeleaf.processor.AbstractProcessor.process(AbstractProcessor.java:212)
    org.thymeleaf.dom.Node.applyNextProcessor(Node.java:1017)
    org.thymeleaf.dom.Node.processNode(Node.java:972)
    org.thymeleaf.dom.NestableNode.computeNextChild(NestableNode.java:695)
    org.thymeleaf.dom.NestableNode.doAdditionalProcess(NestableNode.java:668)
    org.thymeleaf.dom.Node.processNode(Node.java:990)
    org.thymeleaf.dom.NestableNode.computeNextChild(NestableNode.java:695)
    org.thymeleaf.dom.NestableNode.doAdditionalProcess(NestableNode.java:668)
    org.thymeleaf.dom.Node.processNode(Node.java:990)
    org.thymeleaf.dom.NestableNode.computeNextChild(NestableNode.java:695)
    org.thymeleaf.dom.NestableNode.doAdditionalProcess(NestableNode.java:668)
    org.thymeleaf.dom.Node.processNode(Node.java:990)
    org.thymeleaf.dom.NestableNode.computeNextChild(NestableNode.java:695)
    org.thymeleaf.dom.NestableNode.doAdditionalProcess(NestableNode.java:668)
    org.thymeleaf.dom.Node.processNode(Node.java:990)
    org.thymeleaf.dom.NestableNode.computeNextChild(NestableNode.java:695)
    org.thymeleaf.dom.NestableNode.doAdditionalProcess(NestableNode.java:668)
    org.thymeleaf.dom.Node.processNode(Node.java:990)
    org.thymeleaf.dom.NestableNode.computeNextChild(NestableNode.java:695)
    org.thymeleaf.dom.NestableNode.doAdditionalProcess(NestableNode.java:668)
    org.thymeleaf.dom.Node.processNode(Node.java:990)
    org.thymeleaf.dom.NestableNode.computeNextChild(NestableNode.java:695)
    org.thymeleaf.dom.NestableNode.doAdditionalProcess(NestableNode.java:668)
    org.thymeleaf.dom.Node.processNode(Node.java:990)
    org.thymeleaf.dom.Document.process(Document.java:93)
    org.thymeleaf.TemplateEngine.process(TemplateEngine.java:1155)
    org.thymeleaf.TemplateEngine.process(TemplateEngine.java:1060)
    org.thymeleaf.TemplateEngine.process(TemplateEngine.java:1011)
    org.thymeleaf.spring4.view.ThymeleafView.renderFragment(ThymeleafView.java:335)
    org.thymeleaf.spring4.view.ThymeleafView.render(ThymeleafView.java:190)
    org.springframework.web.servlet.DispatcherServlet.render(DispatcherServlet.java:1244)
    org.springframework.web.servlet.DispatcherServlet.processDispatchResult(DispatcherServlet.java:1027)
    org.springframework.web.servlet.DispatcherServlet.doDispatch(DispatcherServlet.java:971)
    org.springframework.web.servlet.DispatcherServlet.doService(DispatcherServlet.java:893)
    org.springframework.web.servlet.FrameworkServlet.processRequest(FrameworkServlet.java:966)
    org.springframework.web.servlet.FrameworkServlet.doGet(FrameworkServlet.java:857)
    javax.servlet.http.HttpServlet.service(HttpServlet.java:622)
    org.springframework.web.servlet.FrameworkServlet.service(FrameworkServlet.java:842)
    javax.servlet.http.HttpServlet.service(HttpServlet.java:729)
    org.apache.tomcat.websocket.server.WsFilter.doFilter(WsFilter.java:52)
    org.springframework.security.web.FilterChainProxy$VirtualFilterChain.doFilter(FilterChainProxy.java:316)
    org.springframework.security.web.access.intercept.FilterSecurityInterceptor.invoke(FilterSecurityInterceptor.java:126)
    org.springframework.security.web.access.intercept.FilterSecurityInterceptor.doFilter(FilterSecurityInterceptor.java:90)
    org.springframework.security.web.FilterChainProxy$VirtualFilterChain.doFilter(FilterChainProxy.java:330)
    org.springframework.security.web.access.ExceptionTranslationFilter.doFilter(ExceptionTranslationFilter.java:114)
    org.springframework.security.web.FilterChainProxy$VirtualFilterChain.doFilter(FilterChainProxy.java:330)
    org.springframework.security.web.session.SessionManagementFilter.doFilter(SessionManagementFilter.java:122)
    org.springframework.security.web.FilterChainProxy$VirtualFilterChain.doFilter(FilterChainProxy.java:330)
    org.springframework.security.web.authentication.AnonymousAuthenticationFilter.doFilter(AnonymousAuthenticationFilter.java:111)
    org.springframework.security.web.FilterChainProxy$VirtualFilterChain.doFilter(FilterChainProxy.java:330)
    org.springframework.security.web.servletapi.SecurityContextHolderAwareRequestFilter.doFilter(SecurityContextHolderAwareRequestFilter.java:169)
    org.springframework.security.web.FilterChainProxy$VirtualFilterChain.doFilter(FilterChainProxy.java:330)
    org.springframework.security.web.savedrequest.RequestCacheAwareFilter.doFilter(RequestCacheAwareFilter.java:48)
    org.springframework.security.web.FilterChainProxy$VirtualFilterChain.doFilter(FilterChainProxy.java:330)
    org.springframework.security.web.authentication.AbstractAuthenticationProcessingFilter.doFilter(AbstractAuthenticationProcessingFilter.java:205)
    org.springframework.security.web.FilterChainProxy$VirtualFilterChain.doFilter(FilterChainProxy.java:330)
    org.springframework.security.web.authentication.logout.LogoutFilter.doFilter(LogoutFilter.java:120)
    org.springframework.security.web.FilterChainProxy$VirtualFilterChain.doFilter(FilterChainProxy.java:330)
    org.springframework.security.web.csrf.CsrfFilter.doFilterInternal(CsrfFilter.java:96)
    org.springframework.web.filter.OncePerRequestFilter.doFilter(OncePerRequestFilter.java:107)
    org.springframework.security.web.FilterChainProxy$VirtualFilterChain.doFilter(FilterChainProxy.java:330)
    org.springframework.security.web.header.HeaderWriterFilter.doFilterInternal(HeaderWriterFilter.java:64)
    org.springframework.web.filter.OncePerRequestFilter.doFilter(OncePerRequestFilter.java:107)
    org.springframework.security.web.FilterChainProxy$VirtualFilterChain.doFilter(FilterChainProxy.java:330)
    org.springframework.security.web.context.request.async.WebAsyncManagerIntegrationFilter.doFilterInternal(WebAsyncManagerIntegrationFilter.java:53)
    org.springframework.web.filter.OncePerRequestFilter.doFilter(OncePerRequestFilter.java:107)
    org.springframework.security.web.FilterChainProxy$VirtualFilterChain.doFilter(FilterChainProxy.java:330)
    org.springframework.security.web.context.SecurityContextPersistenceFilter.doFilter(SecurityContextPersistenceFilter.java:91)
    org.springframework.security.web.FilterChainProxy$VirtualFilterChain.doFilter(FilterChainProxy.java:330)
    org.springframework.security.web.FilterChainProxy.doFilterInternal(FilterChainProxy.java:213)
    org.springframework.security.web.FilterChainProxy.doFilter(FilterChainProxy.java:176)
    org.springframework.web.filter.DelegatingFilterProxy.invokeDelegate(DelegatingFilterProxy.java:344)
    org.springframework.web.filter.DelegatingFilterProxy.doFilter(DelegatingFilterProxy.java:261)

怎么了？我在 thymeleaf 的配置中遗漏了什么吗？

【问题讨论】：

    标签： spring exception authorization expression thymeleaf


    【解决方案1】：

    否定thymeleaf表达式的正确方法是在它前面添加单词not：

     th:if="not ${#authorization.expression('isAuthenticated()')}"

    或者作为另一个例子：

    th:if="${not #lists.isEmpty(pager)}"

    我相信这就是你要找的。​​p>

    【讨论】：

      【解决方案2】：

      问题是我没有在模板引擎中包含 SpringSecurity 方言：

      <bean id="templateEngine" class="org.thymeleaf.spring3.SpringTemplateEngine">
      ...
      <property name="additionalDialects">
        <set>
          <!-- Note the package would change to 'springsecurity3' if you are using that version -->
          <bean class="org.thymeleaf.extras.springsecurity4.dialect.SpringSecurityDialect"/>
        </set>
      </property>
      ...
</bean>

      改正后，一切正常。

      【讨论】：

        【解决方案3】：

        使用注释：

            @Configuration
    @EnableWebMvc
    public class WebMvcConfig extends WebMvcConfigurerAdapter {
    ...
        @Bean
        public SpringTemplateEngine templateEngine() {
            SpringTemplateEngine templateEngine = new SpringTemplateEngine();
            ...
            templateEngine.addDialect(new SpringSecurityDialect());
        return templateEngine;
}

        【讨论】：

          【解决方案4】：

          我也收到此错误“org.springframework.expression.spel.SpelEvaluationException: EL1007E: Property or field 'userPrincipal' cannot be found on null”

          我在 pom.xml 文件中添加了以下内容，错误得到了解决。 1.依赖

          <dependency>
        <groupId>org.thymeleaf.extras</groupId>
        <artifactId>thymeleaf-extras-springsecurity5</artifactId>
        <version>3.0.4.RELEASE</version>
    </dependency>

    </dependency>

          2。在标签下面添加：

          <thymeleaf.version>3.0.2.RELEASE</thymeleaf.version>
    <thymeleaf-layout-dialect.version>2.1.1</thymeleaf-layout-dialect.version>

          【讨论】：

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