java - 用户实体上的某些 REST 操作的 com.fasterxml.jackson.databind.exc.InvalidDefinitionException

Question

我有一些实体:用户、角色、权限。对于所有三个实体，我有三个操作，然后将它们公开为 REST api。 findOne()、findAll() 和 create()。问题是:
角色:所有三个操作都有效。
权限:所有三个操作都有效。
User:findOne() 和 create() 给出 com.fasterxml.jackson.databind.exc.InvalidDefinitionException。但是 findAll() 正常工作。下面是我的代码

用户.java

@Entity
// @JsonIgnoreProperties({"hibernateLazyInitializer", "handler"})
public class User implements Serializable {

    @Id
    @GeneratedValue(strategy = GenerationType.AUTO)
    @Column(name = "USER_ID")
    private Long userId;

    @EmailWithTld
    @Column(nullable = false, unique = true)
    private String email;

    @NotNull
    @Size(min = 2, max = 255)
    private String name;

    private Boolean locked;

    @NotNull
    @Size(max = 255)
    private String password;

    @ManyToMany(fetch = FetchType.EAGER)
    @JoinTable(name = "user_role", joinColumns = { @JoinColumn(name = "USER_ID") }, inverseJoinColumns = {
            @JoinColumn(name = "ROLE_ID") })
    private Set<Role> roles = new HashSet<>();    

    // constructor & getters/setters    
}    

角色.java

@Entity
public class Role implements Serializable {

  @Id
  @GeneratedValue(strategy = GenerationType.AUTO)
  @Column(name = "ROLE_ID")
  public Long roleId;

  @NotNull
  @Size(max = 255)
  public String name;

  @JsonIgnore
  @ManyToMany(mappedBy = "roles")
  private Set<User> users = new HashSet<>();

  @ManyToMany(cascade=CascadeType.ALL,fetch=FetchType.EAGER)
  @JoinTable(name="role_privilege", 
            joinColumns= {@JoinColumn(name="ROLE_ID")},
            inverseJoinColumns = {@JoinColumn(name="PRIV_ID")}          
  )
  private Set<Privilege> privileges = new HashSet<>();    

    // constructor & getters/setters     
}    

用户 Controller

@RestController
@RequestMapping("/users")
public class UserController {

    @Autowired
    private UserService userService;

    @RequestMapping(method = RequestMethod.GET)
    public List<User> findAll() {
        System.out.println(userService);
        List<User> users = userService.findAll();   
        return users;
    }

    @RequestMapping(value = "/{id}", method = RequestMethod.GET)
    public User findOne(@PathVariable("id") final Long userId) {
        return userService.findOne(userId);
    }

    @RequestMapping(method = RequestMethod.POST)
    @ResponseStatus(code = HttpStatus.CREATED)
    public void create( @RequestBody @Valid final User user) {
        userService.create(user);
    }
}   

用户服务:

@Service
@Transactional
public class UserService {

    @Autowired
    private UserJpaRepository userJpaRepository;

    public List<User> findAll(){
        return userJpaRepository.findAll();
    }

    public User findOne(Long userId) {
        User user = userJpaRepository.getOne(userId);
        if(user.getName() != null) {}
        return user;
    }

    public void create(User user) {
        userJpaRepository.save(user);
    }


}  

我查看了许多 StackOverFlow 线程，找到了使用 @JsonIgnoreProperties({"hibernateLazyInitializer", "handler"}) 的解决方案，它也适合我。但我的问题是:
1. 仅针对 User 实体的 findOne() 和 create() 操作导致此问题的原因。 2. 为什么其他实体不会出现此错误，即使它们具有完全相同的操作。
3. @JsonIgnoreProperties 使用安全吗？

当我尝试使用 REST 客户端使用 create() 或 findOne() 时，完整的堆栈跟踪:

com.fasterxml.jackson.databind.exc.InvalidDefinitionException: No serializer found for class org.hibernate.proxy.pojo.javassist.JavassistLazyInitializer and no properties discovered to create BeanSerializer (to avoid exception, disable SerializationFeature.FAIL_ON_EMPTY_BEANS) (through reference chain: com.learn.persistence.model.User_$$_jvstdd2_3["handler"])
    at com.fasterxml.jackson.databind.exc.InvalidDefinitionException.from(InvalidDefinitionException.java:77) ~[jackson-databind-2.9.5.jar:2.9.5]
    at com.fasterxml.jackson.databind.SerializerProvider.reportBadDefinition(SerializerProvider.java:1191) ~[jackson-databind-2.9.5.jar:2.9.5]
    at com.fasterxml.jackson.databind.DatabindContext.reportBadDefinition(DatabindContext.java:312) ~[jackson-databind-2.9.5.jar:2.9.5]
    at com.fasterxml.jackson.databind.ser.impl.UnknownSerializer.failForEmpty(UnknownSerializer.java:71) ~[jackson-databind-2.9.5.jar:2.9.5]
    at com.fasterxml.jackson.databind.ser.impl.UnknownSerializer.serialize(UnknownSerializer.java:33) ~[jackson-databind-2.9.5.jar:2.9.5]
    at com.fasterxml.jackson.databind.ser.BeanPropertyWriter.serializeAsField(BeanPropertyWriter.java:727) ~[jackson-databind-2.9.5.jar:2.9.5]
    at com.fasterxml.jackson.databind.ser.std.BeanSerializerBase.serializeFields(BeanSerializerBase.java:719) ~[jackson-databind-2.9.5.jar:2.9.5]
    at com.fasterxml.jackson.databind.ser.BeanSerializer.serialize(BeanSerializer.java:155) ~[jackson-databind-2.9.5.jar:2.9.5]
    at com.fasterxml.jackson.databind.ser.DefaultSerializerProvider._serialize(DefaultSerializerProvider.java:480) ~[jackson-databind-2.9.5.jar:2.9.5]
    at com.fasterxml.jackson.databind.ser.DefaultSerializerProvider.serializeValue(DefaultSerializerProvider.java:319) ~[jackson-databind-2.9.5.jar:2.9.5]
    at com.fasterxml.jackson.databind.ObjectWriter$Prefetch.serialize(ObjectWriter.java:1396) ~[jackson-databind-2.9.5.jar:2.9.5]
    at com.fasterxml.jackson.databind.ObjectWriter.writeValue(ObjectWriter.java:913) ~[jackson-databind-2.9.5.jar:2.9.5]
    at org.springframework.http.converter.json.AbstractJackson2HttpMessageConverter.writeInternal(AbstractJackson2HttpMessageConverter.java:286) ~[spring-web-5.0.6.RELEASE.jar:5.0.6.RELEASE]
    at org.springframework.http.converter.AbstractGenericHttpMessageConverter.write(AbstractGenericHttpMessageConverter.java:102) ~[spring-web-5.0.6.RELEASE.jar:5.0.6.RELEASE]
    at org.springframework.web.servlet.mvc.method.annotation.AbstractMessageConverterMethodProcessor.writeWithMessageConverters(AbstractMessageConverterMethodProcessor.java:272) ~[spring-webmvc-5.0.6.RELEASE.jar:5.0.6.RELEASE]
    at org.springframework.web.servlet.mvc.method.annotation.RequestResponseBodyMethodProcessor.handleReturnValue(RequestResponseBodyMethodProcessor.java:180) ~[spring-webmvc-5.0.6.RELEASE.jar:5.0.6.RELEASE]
    at org.springframework.web.method.support.HandlerMethodReturnValueHandlerComposite.handleReturnValue(HandlerMethodReturnValueHandlerComposite.java:82) ~[spring-web-5.0.6.RELEASE.jar:5.0.6.RELEASE]
    at org.springframework.web.servlet.mvc.method.annotation.ServletInvocableHandlerMethod.invokeAndHandle(ServletInvocableHandlerMethod.java:119) ~[spring-webmvc-5.0.6.RELEASE.jar:5.0.6.RELEASE]
    at org.springframework.web.servlet.mvc.method.annotation.RequestMappingHandlerAdapter.invokeHandlerMethod(RequestMappingHandlerAdapter.java:877) ~[spring-webmvc-5.0.6.RELEASE.jar:5.0.6.RELEASE]
    at org.springframework.web.servlet.mvc.method.annotation.RequestMappingHandlerAdapter.handleInternal(RequestMappingHandlerAdapter.java:783) ~[spring-webmvc-5.0.6.RELEASE.jar:5.0.6.RELEASE]
    at org.springframework.web.servlet.mvc.method.AbstractHandlerMethodAdapter.handle(AbstractHandlerMethodAdapter.java:87) ~[spring-webmvc-5.0.6.RELEASE.jar:5.0.6.RELEASE]
    at org.springframework.web.servlet.DispatcherServlet.doDispatch(DispatcherServlet.java:991) ~[spring-webmvc-5.0.6.RELEASE.jar:5.0.6.RELEASE]
    at org.springframework.web.servlet.DispatcherServlet.doService(DispatcherServlet.java:925) ~[spring-webmvc-5.0.6.RELEASE.jar:5.0.6.RELEASE]
    at org.springframework.web.servlet.FrameworkServlet.processRequest(FrameworkServlet.java:974) ~[spring-webmvc-5.0.6.RELEASE.jar:5.0.6.RELEASE]
    at org.springframework.web.servlet.FrameworkServlet.doGet(FrameworkServlet.java:866) ~[spring-webmvc-5.0.6.RELEASE.jar:5.0.6.RELEASE]
    at javax.servlet.http.HttpServlet.service(HttpServlet.java:635) ~[tomcat-embed-core-8.5.31.jar:8.5.31]
    at org.springframework.web.servlet.FrameworkServlet.service(FrameworkServlet.java:851) ~[spring-webmvc-5.0.6.RELEASE.jar:5.0.6.RELEASE]
    at javax.servlet.http.HttpServlet.service(HttpServlet.java:742) ~[tomcat-embed-core-8.5.31.jar:8.5.31]
    at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:231) ~[tomcat-embed-core-8.5.31.jar:8.5.31]
    at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:166) ~[tomcat-embed-core-8.5.31.jar:8.5.31]
    at org.apache.tomcat.websocket.server.WsFilter.doFilter(WsFilter.java:52) ~[tomcat-embed-websocket-8.5.31.jar:8.5.31]
    at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:193) ~[tomcat-embed-core-8.5.31.jar:8.5.31]
    at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:166) ~[tomcat-embed-core-8.5.31.jar:8.5.31]
    at org.springframework.security.web.FilterChainProxy$VirtualFilterChain.doFilter(FilterChainProxy.java:320) ~[spring-security-web-5.0.5.RELEASE.jar:5.0.5.RELEASE]
    at org.springframework.security.web.access.intercept.FilterSecurityInterceptor.invoke(FilterSecurityInterceptor.java:127) ~[spring-security-web-5.0.5.RELEASE.jar:5.0.5.RELEASE]
    at org.springframework.security.web.access.intercept.FilterSecurityInterceptor.doFilter(FilterSecurityInterceptor.java:91) ~[spring-security-web-5.0.5.RELEASE.jar:5.0.5.RELEASE]
    at org.springframework.security.web.FilterChainProxy$VirtualFilterChain.doFilter(FilterChainProxy.java:334) ~[spring-security-web-5.0.5.RELEASE.jar:5.0.5.RELEASE]
    at org.springframework.security.web.access.ExceptionTranslationFilter.doFilter(ExceptionTranslationFilter.java:119) ~[spring-security-web-5.0.5.RELEASE.jar:5.0.5.RELEASE]
    at org.springframework.security.web.FilterChainProxy$VirtualFilterChain.doFilter(FilterChainProxy.java:334) ~[spring-security-web-5.0.5.RELEASE.jar:5.0.5.RELEASE]
    at org.springframework.security.web.session.SessionManagementFilter.doFilter(SessionManagementFilter.java:137) ~[spring-security-web-5.0.5.RELEASE.jar:5.0.5.RELEASE]
    at org.springframework.security.web.FilterChainProxy$VirtualFilterChain.doFilter(FilterChainProxy.java:334) ~[spring-security-web-5.0.5.RELEASE.jar:5.0.5.RELEASE]
    at org.springframework.security.web.authentication.AnonymousAuthenticationFilter.doFilter(AnonymousAuthenticationFilter.java:111) ~[spring-security-web-5.0.5.RELEASE.jar:5.0.5.RELEASE]
    at org.springframework.security.web.FilterChainProxy$VirtualFilterChain.doFilter(FilterChainProxy.java:334) ~[spring-security-web-5.0.5.RELEASE.jar:5.0.5.RELEASE]
    at org.springframework.security.web.servletapi.SecurityContextHolderAwareRequestFilter.doFilter(SecurityContextHolderAwareRequestFilter.java:170) ~[spring-security-web-5.0.5.RELEASE.jar:5.0.5.RELEASE]
    at org.springframework.security.web.FilterChainProxy$VirtualFilterChain.doFilter(FilterChainProxy.java:334) ~[spring-security-web-5.0.5.RELEASE.jar:5.0.5.RELEASE]
    at org.springframework.security.web.savedrequest.RequestCacheAwareFilter.doFilter(RequestCacheAwareFilter.java:63) ~[spring-security-web-5.0.5.RELEASE.jar:5.0.5.RELEASE]
    at org.springframework.security.web.FilterChainProxy$VirtualFilterChain.doFilter(FilterChainProxy.java:334) ~[spring-security-web-5.0.5.RELEASE.jar:5.0.5.RELEASE]
    at org.springframework.security.web.authentication.www.BasicAuthenticationFilter.doFilterInternal(BasicAuthenticationFilter.java:215) ~[spring-security-web-5.0.5.RELEASE.jar:5.0.5.RELEASE]
    at org.springframework.web.filter.OncePerRequestFilter.doFilter(OncePerRequestFilter.java:107) ~[spring-web-5.0.6.RELEASE.jar:5.0.6.RELEASE]
    at org.springframework.security.web.FilterChainProxy$VirtualFilterChain.doFilter(FilterChainProxy.java:334) ~[spring-security-web-5.0.5.RELEASE.jar:5.0.5.RELEASE]
    at org.springframework.security.web.authentication.logout.LogoutFilter.doFilter(LogoutFilter.java:116) ~[spring-security-web-5.0.5.RELEASE.jar:5.0.5.RELEASE]
    at org.springframework.security.web.FilterChainProxy$VirtualFilterChain.doFilter(FilterChainProxy.java:334) ~[spring-security-web-5.0.5.RELEASE.jar:5.0.5.RELEASE]
    at org.springframework.security.web.csrf.CsrfFilter.doFilterInternal(CsrfFilter.java:100) ~[spring-security-web-5.0.5.RELEASE.jar:5.0.5.RELEASE]
    at org.springframework.web.filter.OncePerRequestFilter.doFilter(OncePerRequestFilter.java:107) ~[spring-web-5.0.6.RELEASE.jar:5.0.6.RELEASE]
    at org.springframework.security.web.FilterChainProxy$VirtualFilterChain.doFilter(FilterChainProxy.java:334) ~[spring-security-web-5.0.5.RELEASE.jar:5.0.5.RELEASE]
    at org.springframework.security.web.header.HeaderWriterFilter.doFilterInternal(HeaderWriterFilter.java:66) ~[spring-security-web-5.0.5.RELEASE.jar:5.0.5.RELEASE]
    at org.springframework.web.filter.OncePerRequestFilter.doFilter(OncePerRequestFilter.java:107) ~[spring-web-5.0.6.RELEASE.jar:5.0.6.RELEASE]
    at org.springframework.security.web.FilterChainProxy$VirtualFilterChain.doFilter(FilterChainProxy.java:334) ~[spring-security-web-5.0.5.RELEASE.jar:5.0.5.RELEASE]
    at org.springframework.security.web.context.SecurityContextPersistenceFilter.doFilter(SecurityContextPersistenceFilter.java:105) ~[spring-security-web-5.0.5.RELEASE.jar:5.0.5.RELEASE]
    at org.springframework.security.web.FilterChainProxy$VirtualFilterChain.doFilter(FilterChainProxy.java:334) ~[spring-security-web-5.0.5.RELEASE.jar:5.0.5.RELEASE]
    at org.springframework.security.web.context.request.async.WebAsyncManagerIntegrationFilter.doFilterInternal(WebAsyncManagerIntegrationFilter.java:56) ~[spring-security-web-5.0.5.RELEASE.jar:5.0.5.RELEASE]
    at org.springframework.web.filter.OncePerRequestFilter.doFilter(OncePerRequestFilter.java:107) ~[spring-web-5.0.6.RELEASE.jar:5.0.6.RELEASE]
    at org.springframework.security.web.FilterChainProxy$VirtualFilterChain.doFilter(FilterChainProxy.java:334) ~[spring-security-web-5.0.5.RELEASE.jar:5.0.5.RELEASE]
    at org.springframework.security.web.FilterChainProxy.doFilterInternal(FilterChainProxy.java:215) ~[spring-security-web-5.0.5.RELEASE.jar:5.0.5.RELEASE]
    at org.springframework.security.web.FilterChainProxy.doFilter(FilterChainProxy.java:178) ~[spring-security-web-5.0.5.RELEASE.jar:5.0.5.RELEASE]
    at org.springframework.web.filter.DelegatingFilterProxy.invokeDelegate(DelegatingFilterProxy.java:357) ~[spring-web-5.0.6.RELEASE.jar:5.0.6.RELEASE]
    at org.springframework.web.filter.DelegatingFilterProxy.doFilter(DelegatingFilterProxy.java:270) ~[spring-web-5.0.6.RELEASE.jar:5.0.6.RELEASE]
    at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:193) ~[tomcat-embed-core-8.5.31.jar:8.5.31]
    at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:166) ~[tomcat-embed-core-8.5.31.jar:8.5.31]
    at org.springframework.web.filter.CharacterEncodingFilter.doFilterInternal(CharacterEncodingFilter.java:200) ~[spring-web-5.0.6.RELEASE.jar:5.0.6.RELEASE]
    at org.springframework.web.filter.OncePerRequestFilter.doFilter(OncePerRequestFilter.java:107) ~[spring-web-5.0.6.RELEASE.jar:5.0.6.RELEASE]
    at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:193) ~[tomcat-embed-core-8.5.31.jar:8.5.31]
    at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:166) ~[tomcat-embed-core-8.5.31.jar:8.5.31]
    at org.apache.catalina.core.StandardWrapperValve.invoke(StandardWrapperValve.java:198) ~[tomcat-embed-core-8.5.31.jar:8.5.31]
    at org.apache.catalina.core.StandardContextValve.invoke(StandardContextValve.java:96) [tomcat-embed-core-8.5.31.jar:8.5.31]
    at org.apache.catalina.authenticator.AuthenticatorBase.invoke(AuthenticatorBase.java:496) [tomcat-embed-core-8.5.31.jar:8.5.31]
    at org.apache.catalina.core.StandardHostValve.invoke(StandardHostValve.java:140) [tomcat-embed-core-8.5.31.jar:8.5.31]
    at org.apache.catalina.valves.ErrorReportValve.invoke(ErrorReportValve.java:81) [tomcat-embed-core-8.5.31.jar:8.5.31]
    at org.apache.catalina.core.StandardEngineValve.invoke(StandardEngineValve.java:87) [tomcat-embed-core-8.5.31.jar:8.5.31]
    at org.apache.catalina.connector.CoyoteAdapter.service(CoyoteAdapter.java:342) [tomcat-embed-core-8.5.31.jar:8.5.31]
    at org.apache.coyote.http11.Http11Processor.service(Http11Processor.java:803) [tomcat-embed-core-8.5.31.jar:8.5.31]
    at org.apache.coyote.AbstractProcessorLight.process(AbstractProcessorLight.java:66) [tomcat-embed-core-8.5.31.jar:8.5.31]
    at org.apache.coyote.AbstractProtocol$ConnectionHandler.process(AbstractProtocol.java:790) [tomcat-embed-core-8.5.31.jar:8.5.31]
    at org.apache.tomcat.util.net.NioEndpoint$SocketProcessor.doRun(NioEndpoint.java:1468) [tomcat-embed-core-8.5.31.jar:8.5.31]
    at org.apache.tomcat.util.net.SocketProcessorBase.run(SocketProcessorBase.java:49) [tomcat-embed-core-8.5.31.jar:8.5.31]
    at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1149) [na:1.8.0_152]
    at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:624) [na:1.8.0_152]
    at org.apache.tomcat.util.threads.TaskThread$WrappingRunnable.run(TaskThread.java:61) [tomcat-embed-core-8.5.31.jar:8.5.31]
    at java.lang.Thread.run(Thread.java:748) [na:1.8.0_152]

Answer 1

好的，我认为问题是由 Role 对象中用户集合的延迟加载引起的。当您尝试加载User对象时，您还会急切地加载与该对象关联的角色列表。通过这样做，您还可以加载每个角色的用户列表。问题是这个操作是惰性的，这意味着 Jackson 将在加载嵌套对象之前尝试序列化对象。您可以尝试将此 @ManyToMany(mappedBy = "roles") 设置为 Eager，然后重试。但正如本文中提到的:No serializer found for class org.hibernate.proxy.pojo.javassist.Javassist?这只是掩盖了问题。