找不到 SpelEvaluationException 方法答案

【问题标题】：SpelEvaluationException Method cannot be found找不到 SpelEvaluationException 方法
【发布时间】：2017-03-11 01:41:24
【问题描述】：

我正面临下一个问题，当我尝试使用 SpEL 将用户传递给服务方法时，

evaluate expression="commonService.userTest(user)" result="flowScope.user"

spring 抛出了以下异常：

org.springframework.expression.spel.SpelEvaluationException: EL1004E:(pos 14): Method call: Method userTest(com.x.domain.common.User) 在 com.sun.proxy.$Proxy114 type

但是当我传递纯文本而不是用户对象时，

evaluate expression="commonService.userTest('Hello')" result="flowScope.user"

没有错误。

@Entity
@Table(name = "users")
@Getter
@Setter
@NoArgsConstructor
@Slf4j
public class User extends BaseEntity implements UserDetails {

    @Column(unique = true)
    @NotEmpty
    private String username;

    @Column
    @NotEmpty
    @Size(min = 5)
    private String password;
}

@Service("commonService")
public class CommonServiceImpl implements CommonService {
    @Transactional(readOnly = true)
    @Override
    public User userTest(String name) {
        User user = createUser();
        user.setUsername(name);
        return user;
    }
    @Transactional(readOnly = true)
    @Override
    public User userTest(User user) {
        return user;
    }
}

【问题讨论】：

标签： java spring spring-mvc spring-el spelevaluationexception

【解决方案1】：

更新 #2 - 解决方法

删除 DevTools 依赖解决了问题，但应用此解决方案 Spring Boot Dev Tools & Web Flow don't play nice 但在 src/main/resources/META-INF/ 下创建 spring-devtools.properties 并使用以下行使其完全没有问题

restart.include.spring=/.*\.jar

为什么我没有在链接中提到这一行：

restart.include.spring=/spring-.*\.jar

因为我遇到了这个异常

org.springframework.beans.factory.UnsatisfiedDependencyException: Error creating bean with name 'webFlowConfig': Unsatisfied dependency expressed through field 'webMvcConfig'; nested exception is org.springframework.beans.factory.UnsatisfiedDependencyException: Error creating bean with name 'webMvcConfig': Unsatisfied dependency expressed through field 'springTemplateEngine'; nested exception is org.springframework.beans.factory.UnsatisfiedDependencyException: Error creating bean with name 'org.springframework.boot.autoconfigure.thymeleaf.ThymeleafAutoConfiguration$ThymeleafDefaultConfiguration': Unsatisfied dependency expressed through constructor parameter 0; nested exception is org.springframework.beans.factory.BeanCreationException: Error creating bean with name 'defaultTemplateResolver' defined in class path resource [org/springframework/boot/autoconfigure/thymeleaf/ThymeleafAutoConfiguration$Thymeleaf3Configuration$DefaultTemplateResolverConfiguration.class]: Bean instantiation via factory method failed; nested exception is org.springframework.beans.BeanInstantiationException: Failed to instantiate [org.thymeleaf.spring4.templateresolver.SpringResourceTemplateResolver]: Factory method 'defaultTemplateResolver' threw exception; nested exception is java.lang.LinkageError: loader constraint violation: when resolving method "org.thymeleaf.spring4.templateresolver.SpringResourceTemplateResolver.setApplicationContext(Lorg/springframework/context/ApplicationContext;)V" the class loader (instance of org/springframework/boot/devtools/restart/classloader/RestartClassLoader) of the current class, org/springframework/boot/autoconfigure/thymeleaf/AbstractTemplateResolverConfiguration, and the class loader (instance of sun/misc/Launcher$AppClassLoader) for the method's defining class, org/thymeleaf/spring4/templateresolver/SpringResourceTemplateResolver, have different Class objects for the type org/springframework/context/ApplicationContext used in the signature
    at org.springframework.beans.factory.annotation.AutowiredAnnotationBeanPostProcessor$AutowiredFieldElement.inject(AutowiredAnnotationBeanPostProcessor.java:588) ~[spring-beans-4.3.10.RELEASE.jar:4.3.10.RELEASE]
    at org.springframework.beans.factory.annotation.InjectionMetadata.inject(InjectionMetadata.java:88) ~[spring-beans-4.3.10.RELEASE.jar:4.3.10.RELEASE]
    at org.springframework.beans.factory.annotation.AutowiredAnnotationBeanPostProcessor.postProcessPropertyValues(AutowiredAnnotationBeanPostProcessor.java:366) ~[spring-beans-4.3.10.RELEASE.jar:4.3.10.RELEASE]
    at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.populateBean(AbstractAutowireCapableBeanFactory.java:1264) ~[spring-beans-4.3.10.RELEASE.jar:4.3.10.RELEASE]
    at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.doCreateBean(AbstractAutowireCapableBeanFactory.java:553) ~[spring-beans-4.3.10.RELEASE.jar:4.3.10.RELEASE]
    at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.createBean(AbstractAutowireCapableBeanFactory.java:483) ~[spring-beans-4.3.10.RELEASE.jar:4.3.10.RELEASE]
    at org.springframework.beans.factory.support.AbstractBeanFactory$1.getObject(AbstractBeanFactory.java:306) ~[spring-beans-4.3.10.RELEASE.jar:4.3.10.RELEASE]
    at org.springframework.beans.factory.support.DefaultSingletonBeanRegistry.getSingleton(DefaultSingletonBeanRegistry.java:230) ~[spring-beans-4.3.10.RELEASE.jar:4.3.10.RELEASE]
    at org.springframework.beans.factory.support.AbstractBeanFactory.doGetBean(AbstractBeanFactory.java:302) ~[spring-beans-4.3.10.RELEASE.jar:4.3.10.RELEASE]
    at org.springframework.beans.factory.support.AbstractBeanFactory.getBean(AbstractBeanFactory.java:197) ~[spring-beans-4.3.10.RELEASE.jar:4.3.10.RELEASE]
    at org.springframework.beans.factory.support.DefaultListableBeanFactory.preInstantiateSingletons(DefaultListableBeanFactory.java:761) ~[spring-beans-4.3.10.RELEASE.jar:4.3.10.RELEASE]
    at org.springframework.context.support.AbstractApplicationContext.finishBeanFactoryInitialization(AbstractApplicationContext.java:867) ~[spring-context-4.3.10.RELEASE.jar:4.3.10.RELEASE]
    at org.springframework.context.support.AbstractApplicationContext.refresh(AbstractApplicationContext.java:543) ~[spring-context-4.3.10.RELEASE.jar:4.3.10.RELEASE]
    at org.springframework.boot.context.embedded.EmbeddedWebApplicationContext.refresh(EmbeddedWebApplicationContext.java:122) ~[spring-boot-1.5.6.RELEASE.jar:1.5.6.RELEASE]
    at org.springframework.boot.SpringApplication.refresh(SpringApplication.java:693) [spring-boot-1.5.6.RELEASE.jar:1.5.6.RELEASE]
    at org.springframework.boot.SpringApplication.refreshContext(SpringApplication.java:360) [spring-boot-1.5.6.RELEASE.jar:1.5.6.RELEASE]
    at org.springframework.boot.SpringApplication.run(SpringApplication.java:303) [spring-boot-1.5.6.RELEASE.jar:1.5.6.RELEASE]
    at org.springframework.boot.SpringApplication.run(SpringApplication.java:1118) [spring-boot-1.5.6.RELEASE.jar:1.5.6.RELEASE]
    at org.springframework.boot.SpringApplication.run(SpringApplication.java:1107) [spring-boot-1.5.6.RELEASE.jar:1.5.6.RELEASE]
    at medicallab.MedicallabApplication.main(MedicallabApplication.java:10) [classes/:na]
    at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method) ~[na:1.8.0_121]
    at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62) ~[na:1.8.0_121]
    at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43) ~[na:1.8.0_121]
    at java.lang.reflect.Method.invoke(Method.java:498) ~[na:1.8.0_121]
    at org.springframework.boot.devtools.restart.RestartLauncher.run(RestartLauncher.java:49) [spring-boot-devtools-1.5.6.RELEASE.jar:1.5.6.RELEASE]
Caused by: org.springframework.beans.factory.UnsatisfiedDependencyException: Error creating bean with name 'webMvcConfig': Unsatisfied dependency expressed through field 'springTemplateEngine'; nested exception is org.springframework.beans.factory.UnsatisfiedDependencyException: Error creating bean with name 'org.springframework.boot.autoconfigure.thymeleaf.ThymeleafAutoConfiguration$ThymeleafDefaultConfiguration': Unsatisfied dependency expressed through constructor parameter 0; nested exception is org.springframework.beans.factory.BeanCreationException: Error creating bean with name 'defaultTemplateResolver' defined in class path resource [org/springframework/boot/autoconfigure/thymeleaf/ThymeleafAutoConfiguration$Thymeleaf3Configuration$DefaultTemplateResolverConfiguration.class]: Bean instantiation via factory method failed; nested exception is org.springframework.beans.BeanInstantiationException: Failed to instantiate [org.thymeleaf.spring4.templateresolver.SpringResourceTemplateResolver]: Factory method 'defaultTemplateResolver' threw exception; nested exception is java.lang.LinkageError: loader constraint violation: when resolving method "org.thymeleaf.spring4.templateresolver.SpringResourceTemplateResolver.setApplicationContext(Lorg/springframework/context/ApplicationContext;)V" the class loader (instance of org/springframework/boot/devtools/restart/classloader/RestartClassLoader) of the current class, org/springframework/boot/autoconfigure/thymeleaf/AbstractTemplateResolverConfiguration, and the class loader (instance of sun/misc/Launcher$AppClassLoader) for the method's defining class, org/thymeleaf/spring4/templateresolver/SpringResourceTemplateResolver, have different Class objects for the type org/springframework/context/ApplicationContext used in the signature
    at org.springframework.beans.factory.annotation.AutowiredAnnotationBeanPostProcessor$AutowiredFieldElement.inject(AutowiredAnnotationBeanPostProcessor.java:588) ~[spring-beans-4.3.10.RELEASE.jar:4.3.10.RELEASE]
    at org.springframework.beans.factory.annotation.InjectionMetadata.inject(InjectionMetadata.java:88) ~[spring-beans-4.3.10.RELEASE.jar:4.3.10.RELEASE]
    at org.springframework.beans.factory.annotation.AutowiredAnnotationBeanPostProcessor.postProcessPropertyValues(AutowiredAnnotationBeanPostProcessor.java:366) ~[spring-beans-4.3.10.RELEASE.jar:4.3.10.RELEASE]
    at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.populateBean(AbstractAutowireCapableBeanFactory.java:1264) ~[spring-beans-4.3.10.RELEASE.jar:4.3.10.RELEASE]
    at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.doCreateBean(AbstractAutowireCapableBeanFactory.java:553) ~[spring-beans-4.3.10.RELEASE.jar:4.3.10.RELEASE]
    at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.createBean(AbstractAutowireCapableBeanFactory.java:483) ~[spring-beans-4.3.10.RELEASE.jar:4.3.10.RELEASE]
    at org.springframework.beans.factory.support.AbstractBeanFactory$1.getObject(AbstractBeanFactory.java:306) ~[spring-beans-4.3.10.RELEASE.jar:4.3.10.RELEASE]
    at org.springframework.beans.factory.support.DefaultSingletonBeanRegistry.getSingleton(DefaultSingletonBeanRegistry.java:230) ~[spring-beans-4.3.10.RELEASE.jar:4.3.10.RELEASE]
    at org.springframework.beans.factory.support.AbstractBeanFactory.doGetBean(AbstractBeanFactory.java:302) ~[spring-beans-4.3.10.RELEASE.jar:4.3.10.RELEASE]
    at org.springframework.beans.factory.support.AbstractBeanFactory.getBean(AbstractBeanFactory.java:202) ~[spring-beans-4.3.10.RELEASE.jar:4.3.10.RELEASE]
    at org.springframework.beans.factory.config.DependencyDescriptor.resolveCandidate(DependencyDescriptor.java:208) ~[spring-beans-4.3.10.RELEASE.jar:4.3.10.RELEASE]
    at org.springframework.beans.factory.support.DefaultListableBeanFactory.doResolveDependency(DefaultListableBeanFactory.java:1138) ~[spring-beans-4.3.10.RELEASE.jar:4.3.10.RELEASE]
    at org.springframework.beans.factory.support.DefaultListableBeanFactory.resolveDependency(DefaultListableBeanFactory.java:1066) ~[spring-beans-4.3.10.RELEASE.jar:4.3.10.RELEASE]
    at org.springframework.beans.factory.annotation.AutowiredAnnotationBeanPostProcessor$AutowiredFieldElement.inject(AutowiredAnnotationBeanPostProcessor.java:585) ~[spring-beans-4.3.10.RELEASE.jar:4.3.10.RELEASE]
    ... 24 common frames omitted
Caused by: org.springframework.beans.factory.UnsatisfiedDependencyException: Error creating bean with name 'org.springframework.boot.autoconfigure.thymeleaf.ThymeleafAutoConfiguration$ThymeleafDefaultConfiguration': Unsatisfied dependency expressed through constructor parameter 0; nested exception is org.springframework.beans.factory.BeanCreationException: Error creating bean with name 'defaultTemplateResolver' defined in class path resource [org/springframework/boot/autoconfigure/thymeleaf/ThymeleafAutoConfiguration$Thymeleaf3Configuration$DefaultTemplateResolverConfiguration.class]: Bean instantiation via factory method failed; nested exception is org.springframework.beans.BeanInstantiationException: Failed to instantiate [org.thymeleaf.spring4.templateresolver.SpringResourceTemplateResolver]: Factory method 'defaultTemplateResolver' threw exception; nested exception is java.lang.LinkageError: loader constraint violation: when resolving method "org.thymeleaf.spring4.templateresolver.SpringResourceTemplateResolver.setApplicationContext(Lorg/springframework/context/ApplicationContext;)V" the class loader (instance of org/springframework/boot/devtools/restart/classloader/RestartClassLoader) of the current class, org/springframework/boot/autoconfigure/thymeleaf/AbstractTemplateResolverConfiguration, and the class loader (instance of sun/misc/Launcher$AppClassLoader) for the method's defining class, org/thymeleaf/spring4/templateresolver/SpringResourceTemplateResolver, have different Class objects for the type org/springframework/context/ApplicationContext used in the signature
    at org.springframework.beans.factory.support.ConstructorResolver.createArgumentArray(ConstructorResolver.java:749) ~[spring-beans-4.3.10.RELEASE.jar:4.3.10.RELEASE]
    at org.springframework.beans.factory.support.ConstructorResolver.autowireConstructor(ConstructorResolver.java:189) ~[spring-beans-4.3.10.RELEASE.jar:4.3.10.RELEASE]
    at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.autowireConstructor(AbstractAutowireCapableBeanFactory.java:1193) ~[spring-beans-4.3.10.RELEASE.jar:4.3.10.RELEASE]
    at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.createBeanInstance(AbstractAutowireCapableBeanFactory.java:1095) ~[spring-beans-4.3.10.RELEASE.jar:4.3.10.RELEASE]
    at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.doCreateBean(AbstractAutowireCapableBeanFactory.java:513) ~[spring-beans-4.3.10.RELEASE.jar:4.3.10.RELEASE]
    at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.createBean(AbstractAutowireCapableBeanFactory.java:483) ~[spring-beans-4.3.10.RELEASE.jar:4.3.10.RELEASE]
    at org.springframework.beans.factory.support.AbstractBeanFactory$1.getObject(AbstractBeanFactory.java:306) ~[spring-beans-4.3.10.RELEASE.jar:4.3.10.RELEASE]
    at org.springframework.beans.factory.support.DefaultSingletonBeanRegistry.getSingleton(DefaultSingletonBeanRegistry.java:230) ~[spring-beans-4.3.10.RELEASE.jar:4.3.10.RELEASE]
    at org.springframework.beans.factory.support.AbstractBeanFactory.doGetBean(AbstractBeanFactory.java:302) ~[spring-beans-4.3.10.RELEASE.jar:4.3.10.RELEASE]
    at org.springframework.beans.factory.support.AbstractBeanFactory.getBean(AbstractBeanFactory.java:197) ~[spring-beans-4.3.10.RELEASE.jar:4.3.10.RELEASE]
    at org.springframework.beans.factory.support.ConstructorResolver.instantiateUsingFactoryMethod(ConstructorResolver.java:372) ~[spring-beans-4.3.10.RELEASE.jar:4.3.10.RELEASE]
    at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.instantiateUsingFactoryMethod(AbstractAutowireCapableBeanFactory.java:1173) ~[spring-beans-4.3.10.RELEASE.jar:4.3.10.RELEASE]
    at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.createBeanInstance(AbstractAutowireCapableBeanFactory.java:1067) ~[spring-beans-4.3.10.RELEASE.jar:4.3.10.RELEASE]
    at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.doCreateBean(AbstractAutowireCapableBeanFactory.java:513) ~[spring-beans-4.3.10.RELEASE.jar:4.3.10.RELEASE]
    at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.createBean(AbstractAutowireCapableBeanFactory.java:483) ~[spring-beans-4.3.10.RELEASE.jar:4.3.10.RELEASE]
    at org.springframework.beans.factory.support.AbstractBeanFactory$1.getObject(AbstractBeanFactory.java:306) ~[spring-beans-4.3.10.RELEASE.jar:4.3.10.RELEASE]
    at org.springframework.beans.factory.support.DefaultSingletonBeanRegistry.getSingleton(DefaultSingletonBeanRegistry.java:230) ~[spring-beans-4.3.10.RELEASE.jar:4.3.10.RELEASE]
    at org.springframework.beans.factory.support.AbstractBeanFactory.doGetBean(AbstractBeanFactory.java:302) ~[spring-beans-4.3.10.RELEASE.jar:4.3.10.RELEASE]
    at org.springframework.beans.factory.support.AbstractBeanFactory.getBean(AbstractBeanFactory.java:202) ~[spring-beans-4.3.10.RELEASE.jar:4.3.10.RELEASE]
    at org.springframework.beans.factory.config.DependencyDescriptor.resolveCandidate(DependencyDescriptor.java:208) ~[spring-beans-4.3.10.RELEASE.jar:4.3.10.RELEASE]
    at org.springframework.beans.factory.support.DefaultListableBeanFactory.doResolveDependency(DefaultListableBeanFactory.java:1138) ~[spring-beans-4.3.10.RELEASE.jar:4.3.10.RELEASE]
    at org.springframework.beans.factory.support.DefaultListableBeanFactory.resolveDependency(DefaultListableBeanFactory.java:1066) ~[spring-beans-4.3.10.RELEASE.jar:4.3.10.RELEASE]
    at org.springframework.beans.factory.annotation.AutowiredAnnotationBeanPostProcessor$AutowiredFieldElement.inject(AutowiredAnnotationBeanPostProcessor.java:585) ~[spring-beans-4.3.10.RELEASE.jar:4.3.10.RELEASE]
    ... 37 common frames omitted
Caused by: org.springframework.beans.factory.BeanCreationException: Error creating bean with name 'defaultTemplateResolver' defined in class path resource [org/springframework/boot/autoconfigure/thymeleaf/ThymeleafAutoConfiguration$Thymeleaf3Configuration$DefaultTemplateResolverConfiguration.class]: Bean instantiation via factory method failed; nested exception is org.springframework.beans.BeanInstantiationException: Failed to instantiate [org.thymeleaf.spring4.templateresolver.SpringResourceTemplateResolver]: Factory method 'defaultTemplateResolver' threw exception; nested exception is java.lang.LinkageError: loader constraint violation: when resolving method "org.thymeleaf.spring4.templateresolver.SpringResourceTemplateResolver.setApplicationContext(Lorg/springframework/context/ApplicationContext;)V" the class loader (instance of org/springframework/boot/devtools/restart/classloader/RestartClassLoader) of the current class, org/springframework/boot/autoconfigure/thymeleaf/AbstractTemplateResolverConfiguration, and the class loader (instance of sun/misc/Launcher$AppClassLoader) for the method's defining class, org/thymeleaf/spring4/templateresolver/SpringResourceTemplateResolver, have different Class objects for the type org/springframework/context/ApplicationContext used in the signature
    at org.springframework.beans.factory.support.ConstructorResolver.instantiateUsingFactoryMethod(ConstructorResolver.java:599) ~[spring-beans-4.3.10.RELEASE.jar:4.3.10.RELEASE]
    at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.instantiateUsingFactoryMethod(AbstractAutowireCapableBeanFactory.java:1173) ~[spring-beans-4.3.10.RELEASE.jar:4.3.10.RELEASE]
    at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.createBeanInstance(AbstractAutowireCapableBeanFactory.java:1067) ~[spring-beans-4.3.10.RELEASE.jar:4.3.10.RELEASE]
    at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.doCreateBean(AbstractAutowireCapableBeanFactory.java:513) ~[spring-beans-4.3.10.RELEASE.jar:4.3.10.RELEASE]
    at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.createBean(AbstractAutowireCapableBeanFactory.java:483) ~[spring-beans-4.3.10.RELEASE.jar:4.3.10.RELEASE]
    at org.springframework.beans.factory.support.AbstractBeanFactory$1.getObject(AbstractBeanFactory.java:306) ~[spring-beans-4.3.10.RELEASE.jar:4.3.10.RELEASE]
    at org.springframework.beans.factory.support.DefaultSingletonBeanRegistry.getSingleton(DefaultSingletonBeanRegistry.java:230) ~[spring-beans-4.3.10.RELEASE.jar:4.3.10.RELEASE]
    at org.springframework.beans.factory.support.AbstractBeanFactory.doGetBean(AbstractBeanFactory.java:302) ~[spring-beans-4.3.10.RELEASE.jar:4.3.10.RELEASE]
    at org.springframework.beans.factory.support.AbstractBeanFactory.getBean(AbstractBeanFactory.java:202) ~[spring-beans-4.3.10.RELEASE.jar:4.3.10.RELEASE]
    at org.springframework.beans.factory.config.DependencyDescriptor.resolveCandidate(DependencyDescriptor.java:208) ~[spring-beans-4.3.10.RELEASE.jar:4.3.10.RELEASE]
    at org.springframework.beans.factory.support.DefaultListableBeanFactory.addCandidateEntry(DefaultListableBeanFactory.java:1316) ~[spring-beans-4.3.10.RELEASE.jar:4.3.10.RELEASE]
    at org.springframework.beans.factory.support.DefaultListableBeanFactory.findAutowireCandidates(DefaultListableBeanFactory.java:1282) ~[spring-beans-4.3.10.RELEASE.jar:4.3.10.RELEASE]
    at org.springframework.beans.factory.support.DefaultListableBeanFactory.resolveMultipleBeans(DefaultListableBeanFactory.java:1180) ~[spring-beans-4.3.10.RELEASE.jar:4.3.10.RELEASE]
    at org.springframework.beans.factory.support.DefaultListableBeanFactory.doResolveDependency(DefaultListableBeanFactory.java:1096) ~[spring-beans-4.3.10.RELEASE.jar:4.3.10.RELEASE]
    at org.springframework.beans.factory.support.DefaultListableBeanFactory.resolveDependency(DefaultListableBeanFactory.java:1066) ~[spring-beans-4.3.10.RELEASE.jar:4.3.10.RELEASE]
    at org.springframework.beans.factory.support.ConstructorResolver.resolveAutowiredArgument(ConstructorResolver.java:835) ~[spring-beans-4.3.10.RELEASE.jar:4.3.10.RELEASE]
    at org.springframework.beans.factory.support.ConstructorResolver.createArgumentArray(ConstructorResolver.java:741) ~[spring-beans-4.3.10.RELEASE.jar:4.3.10.RELEASE]
    ... 59 common frames omitted
Caused by: org.springframework.beans.BeanInstantiationException: Failed to instantiate [org.thymeleaf.spring4.templateresolver.SpringResourceTemplateResolver]: Factory method 'defaultTemplateResolver' threw exception; nested exception is java.lang.LinkageError: loader constraint violation: when resolving method "org.thymeleaf.spring4.templateresolver.SpringResourceTemplateResolver.setApplicationContext(Lorg/springframework/context/ApplicationContext;)V" the class loader (instance of org/springframework/boot/devtools/restart/classloader/RestartClassLoader) of the current class, org/springframework/boot/autoconfigure/thymeleaf/AbstractTemplateResolverConfiguration, and the class loader (instance of sun/misc/Launcher$AppClassLoader) for the method's defining class, org/thymeleaf/spring4/templateresolver/SpringResourceTemplateResolver, have different Class objects for the type org/springframework/context/ApplicationContext used in the signature
    at org.springframework.beans.factory.support.SimpleInstantiationStrategy.instantiate(SimpleInstantiationStrategy.java:189) ~[spring-beans-4.3.10.RELEASE.jar:4.3.10.RELEASE]
    at org.springframework.beans.factory.support.ConstructorResolver.instantiateUsingFactoryMethod(ConstructorResolver.java:588) ~[spring-beans-4.3.10.RELEASE.jar:4.3.10.RELEASE]
    ... 75 common frames omitted
Caused by: java.lang.LinkageError: loader constraint violation: when resolving method "org.thymeleaf.spring4.templateresolver.SpringResourceTemplateResolver.setApplicationContext(Lorg/springframework/context/ApplicationContext;)V" the class loader (instance of org/springframework/boot/devtools/restart/classloader/RestartClassLoader) of the current class, org/springframework/boot/autoconfigure/thymeleaf/AbstractTemplateResolverConfiguration, and the class loader (instance of sun/misc/Launcher$AppClassLoader) for the method's defining class, org/thymeleaf/spring4/templateresolver/SpringResourceTemplateResolver, have different Class objects for the type org/springframework/context/ApplicationContext used in the signature
    at org.springframework.boot.autoconfigure.thymeleaf.AbstractTemplateResolverConfiguration.defaultTemplateResolver(AbstractTemplateResolverConfiguration.java:70) ~[spring-boot-autoconfigure-1.5.6.RELEASE.jar:1.5.6.RELEASE]
    at org.springframework.boot.autoconfigure.thymeleaf.ThymeleafAutoConfiguration$Thymeleaf3Configuration$DefaultTemplateResolverConfiguration.defaultTemplateResolver(ThymeleafAutoConfiguration.java:140) ~[spring-boot-autoconfigure-1.5.6.RELEASE.jar:1.5.6.RELEASE]
    at org.springframework.boot.autoconfigure.thymeleaf.ThymeleafAutoConfiguration$Thymeleaf3Configuration$DefaultTemplateResolverConfiguration$$EnhancerBySpringCGLIB$$f2a7a126.CGLIB$defaultTemplateResolver$0(<generated>) ~[spring-boot-autoconfigure-1.5.6.RELEASE.jar:1.5.6.RELEASE]
    at org.springframework.boot.autoconfigure.thymeleaf.ThymeleafAutoConfiguration$Thymeleaf3Configuration$DefaultTemplateResolverConfiguration$$EnhancerBySpringCGLIB$$f2a7a126$$FastClassBySpringCGLIB$$7a53489b.invoke(<generated>) ~[spring-boot-autoconfigure-1.5.6.RELEASE.jar:1.5.6.RELEASE]
    at org.springframework.cglib.proxy.MethodProxy.invokeSuper(MethodProxy.java:228) ~[spring-core-4.3.10.RELEASE.jar:4.3.10.RELEASE]
    at org.springframework.context.annotation.ConfigurationClassEnhancer$BeanMethodInterceptor.intercept(ConfigurationClassEnhancer.java:358) ~[spring-context-4.3.10.RELEASE.jar:4.3.10.RELEASE]
    at org.springframework.boot.autoconfigure.thymeleaf.ThymeleafAutoConfiguration$Thymeleaf3Configuration$DefaultTemplateResolverConfiguration$$EnhancerBySpringCGLIB$$f2a7a126.defaultTemplateResolver(<generated>) ~[spring-boot-autoconfigure-1.5.6.RELEASE.jar:1.5.6.RELEASE]
    at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method) ~[na:1.8.0_121]
    at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62) ~[na:1.8.0_121]
    at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43) ~[na:1.8.0_121]
    at java.lang.reflect.Method.invoke(Method.java:498) ~[na:1.8.0_121]
    at org.springframework.beans.factory.support.SimpleInstantiationStrategy.instantiate(SimpleInstantiationStrategy.java:162) ~[spring-beans-4.3.10.RELEASE.jar:4.3.10.RELEA

SE]
... 76 common frames omitted

所以我现在必须包括所有的罐子。希望这可能对将来的某人有所帮助，但请参阅Update #1，因为这可能会在将来得到解决Spring DevTools classloader limitations，但这会导致 LiveReload 服务器无法运行.

更新 #1

这似乎是一个 DevTools 问题 (Customizing the restart classloader)，可能很快会修复 Spring DevTools classloader limitations。始于本期Spring Boot Dev Tools & Web Flow don't play nice

原答案

我多次遇到同样的问题，我做了一个测试，发现这是一种奇怪的行为。

public class SomeModel implements Serializable {
    private static final long serialVersionUID = -7967970066125990593L;
    ...
}

CustomFlowAction.java

package app.flow;

public class CustomFlowAction {

    // Note here the paramter is of type Object, just to use casting instead of using the object directly to test if I have the correct one
    public boolean someAction(Object obj, RequestContext context) {
        SomeModel someModel = (SomeModel) obj;
        return true
    }

    public SomeModel prepareSomeModel() {
        return new SomeModel();
    }
}

（流程示例1）some-flow.xml

这个例子使用了一个spring bean，它工作正常并且someAction方法返回true。

<flow ...>
  <view-state id="StateOne"  model="someModel">
    <transition on="next" to="StateTwo">
      <evaluate expression="customFlowAction.someAction(someModel, flowRequestContext)"></evaluate>
    </transition>
  </view-state>
</flow>

（流程示例2）some-flow.xml

此示例从 SomeModel 创建一个新对象并将其存储在 flowScope 中，然后在模板中使用它。

<flow ...>
  <on-start>
    <evaluate expression="submitRequestFlowAction.prepareSomeModel()" result="flowScope.someModel"></evaluate>
  </on-start>

  <view-state id="StateOne"  model="someModel">
    <transition on="next" to="StateTwo">
      <evaluate expression="customFlowAction.someAction(someModel, flowRequestContext)"></evaluate>
    </transition>
  </view-state>
</flow>

输出是：

java.lang.ClassCastException: app.flow.SomeModel cannot be cast to app.flow.SomeModel

有些人引导我发现问题可能涉及另一个类加载器，有人告诉我：

请注意，类加载器是类类型的一部分：A 类，由类加载器 CL1，与类加载器 CL2 加载的 A 类不同，即使 实际的 A.class 可能是同一个文件

希望这对你和其他像我一样遇到麻烦的人有帮助:)

【讨论】：

【解决方案2】：

我收到与从数据库中检索对象相关的错误。为了解决这个问题，我创建了一个服务类，它通过事务调用代理对象并解决了它。

@Transactional(readOnly = true)
public User findOneByCustomerPersonalEmail(String email) {
    User user = userRepository.findOneByCustomerPersonalEmail(email);
    user.getCustomer(); //this line fills the proxied object
    return user;
}

【讨论】：