JsonMappingException：无法初始化代理 - 没有会话

Posted 2023-02-26

【中文标题】JsonMappingException：无法初始化代理 - 没有会话

【英文标题】：JsonMappingException: could not initialize proxy - no Session

【发布时间】：2015-01-13 11:18:53

【问题描述】：

我正在构建一个使用并返回 JSON 的 RESTful Web 服务。当我尝试通过服务层从数据库中获取 ESRBRating 对象时，我遇到了以下堆栈跟踪。但是，当我将 Spring Data JPA 存储库直接注入控制器并使用它按 ID 获取 ESRBRating 时，它工作正常。但是，当通过服务层调用时，它不起作用。我在下面提供了堆栈跟踪和代码。有人可以向我解释为什么在通过服务层而不是直接通过 Spring Data JPA 存储库时会发生这种情况吗？我该如何解决这个问题？

堆栈跟踪

Caused by: org.hibernate.LazyInitializationException: could not initialize proxy - no Session
    at org.hibernate.proxy.AbstractLazyInitializer.initialize(AbstractLazyInitializer.java:165)
    at org.hibernate.proxy.AbstractLazyInitializer.getImplementation(AbstractLazyInitializer.java:286)
    at org.hibernate.proxy.pojo.javassist.JavassistLazyInitializer.invoke(JavassistLazyInitializer.java:185)
    at net.jkratz.igdb.model.ESRBRating_$$_jvst319_0.getId(ESRBRating_$$_jvst319_0.java)
    at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
    at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:57)
    at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
    at java.lang.reflect.Method.invoke(Method.java:606)
    at com.fasterxml.jackson.databind.ser.BeanPropertyWriter.serializeAsField(BeanPropertyWriter.java:466)
    at com.fasterxml.jackson.databind.ser.std.BeanSerializerBase.serializeFields(BeanSerializerBase.java:639)
    ... 76 more

控制器

@RestController
@RequestMapping(produces = "application/json", value="/esrbrating")
public class ESRBRatingController 

    @Inject
    ESRBRatingService esrbRatingService;

    @Inject
    ESRBRatingRepository esrbRatingRepository;

    private Logger logger = LoggerFactory.getLogger(getClass());

    /**
     * Returns all ESRB ratings in database
     * 
     * @return List of ESRBRating objects
     * @see ESRBRating
     */
    @RequestMapping(value = "","/", method = RequestMethod.GET)
    public ResponseEntity<List<ESRBRating>> getESRBRatings() 
        List<ESRBRating> esrbRatings = esrbRatingService.getESRBRatings();
        return new ResponseEntity<>(esrbRatings, HttpStatus.OK);
    

    /**
     * Returns a single ESRB rating object if exists, otherwise returns HTTP status code 404
     *
     * @param id ID of the ESRB Rating
     * @return ESRB Rating when found
     * @see ESRBRating
     */
    @RequestMapping(value = "/id", method = RequestMethod.GET)
    public ResponseEntity<?> getUser(@PathVariable("id") Long id) 
        logger.debug("Attempting to fetch ESRB rating with ID: ", id);
        ESRBRating esrbRating = esrbRatingService.getESRBRating(id);
        //ESRBRating esrbRating = esrbRatingRepository.findOne(id);

        if (esrbRating == null) 
            return new ResponseEntity<>("ESRB Rating not found", HttpStatus.NOT_FOUND);
         else 
            return new ResponseEntity<>(esrbRating, HttpStatus.OK);
        
    

服务

@Service
@Transactional
public class ESRBRatingServiceImpl implements ESRBRatingService 

    @Value("#paging.games.maxPageSize")
    private static int DEFAULT_PAGE_SIZE;

    @Value("#paging.games.maxPageSize")
    private static int MAX_PAGE_SIZE;

    @Inject
    private ESRBRatingRepository esrbRatingRepository;

    @Override
    public List<ESRBRating> getESRBRatings() 
        List<ESRBRating> ratings =  esrbRatingRepository.findAll();
        return ratings;
    

    @Override
    public ESRBRating getESRBRating(Long id) 
        return esrbRatingRepository.getOne(id);
    

    @Override
    public ESRBRating saveESRBRating(ESRBRating esrbRating) 
        return esrbRatingRepository.saveAndFlush(esrbRating);
    

    @Override
    public boolean deleteESRBRating(Long id) 
        esrbRatingRepository.delete(id);
        return true;
    

存储库

package net.jkratz.igdb.repository;

import net.jkratz.igdb.model.ESRBRating;

import org.springframework.data.jpa.repository.JpaRepository;

public interface ESRBRatingRepository extends JpaRepository<ESRBRating, Long> 

型号

@Entity
@Table(name = "esrb_rating", schema = "igdb")
@JsonIgnoreProperties(ignoreUnknown = true)
public class ESRBRating implements Serializable 

    private static final long serialVersionUID = 1L;

    @Id
    @NotNull
    @GeneratedValue(strategy = GenerationType.AUTO)
    @Column(name = "id", nullable = false)
    private Long id;

    @NotNull
    @Size(min = 1, max = 255)
    @Column(name = "title", nullable = false, length = 255)
    private String title;

    @Size(max = 65535)
    @Column(length = 65535)
    private String description;

    @OneToMany(cascade = CascadeType.ALL, mappedBy = "esrbRating")
    private List<Game> games;

    public ESRBRating() 
    

    public ESRBRating(Long id, String title, String description) 
        this.id = id;
        this.title = title;
        this.description = description;
    

    public Long getId() 
        return id;
    

    public void setId(Long id) 
        this.id = id;
    

    public String getTitle() 
        return title;
    

    public void setTitle(String title) 
        this.title = title;
    

    public String getDescription() 
        return description;
    

    public void setDescription(String description) 
        this.description = description;
    

    @Override
    public boolean equals(Object o) 
        if (this == o) return true;
        if (o == null || getClass() != o.getClass()) return false;

        ESRBRating that = (ESRBRating) o;

        return Objects.equal(this.id, that.id) &&
                Objects.equal(this.title, that.title) &&
                Objects.equal(this.description, that.description);
    

    @Override
    public int hashCode() 
        return Objects.hashCode(id, title, description);
    

    @Override
    public String toString() 
        return Objects.toStringHelper(this)
                .add("id", id)
                .add("title", title)
                .add("description", description)
                .toString();
    

此控制器代码工作正常，直接通过存储库。

@RestController
@RequestMapping(produces = "application/json", value="/esrbrating")
public class ESRBRatingController 

@Inject
ESRBRatingService esrbRatingService;

@Inject
ESRBRatingRepository esrbRatingRepository;

private Logger logger = LoggerFactory.getLogger(getClass());

/**
 * Returns all ESRB ratings in database
 * 
 * @return List of ESRBRating objects
 * @see ESRBRating
 */
@RequestMapping(value = "","/", method = RequestMethod.GET)
public ResponseEntity<List<ESRBRating>> getESRBRatings() 
    List<ESRBRating> esrbRatings = esrbRatingService.getESRBRatings();
    return new ResponseEntity<>(esrbRatings, HttpStatus.OK);


/**
 * Returns a single ESRB rating object if exists, otherwise returns HTTP status code 404
 *
 * @param id ID of the ESRB Rating
 * @return ESRB Rating when found
 * @see ESRBRating
 */
@RequestMapping(value = "/id", method = RequestMethod.GET)
public ResponseEntity<?> getUser(@PathVariable("id") Long id) 
    logger.debug("Attempting to fetch ESRB rating with ID: ", id);
    ESRBRating esrbRating = esrbRatingRepository.findOne(id);

    if (esrbRating == null) 
        return new ResponseEntity<>("ESRB Rating not found", HttpStatus.NOT_FOUND);
     else 
        return new ResponseEntity<>(esrbRating, HttpStatus.OK);
    

更新：

我听从了 Randall Harleigh 的建议，并使用 @JsonIgnore 设置了反向集合。但是现在我得到了一个完全不同的堆栈跟踪。现在看来 Jackson / Spring 不知道如何序列化 ESRBRating。关于这个有什么建议吗？

org.springframework.http.converter.HttpMessageNotWritableException: Could not write content: 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: net.jkratz.igdb.model.ESRBRating_$$_jvstb5c_0["handler"]); nested exception is com.fasterxml.jackson.databind.JsonMappingException: No serializer found for class org.hibernate.proxy.pojo.javassist.JavassistLazyInitializer and no properties discovered to create BeanSerializer (to avoid exception, disable SerializationFeature.FAIL_ON_EMPTY_BEANS) ) (through reference chain: net.jkratz.igdb.model.ESRBRating_$$_jvstb5c_0["handler"])
    at org.springframework.http.converter.json.AbstractJackson2HttpMessageConverter.writeInternal(AbstractJackson2HttpMessageConverter.java:238)
    at org.springframework.http.converter.AbstractHttpMessageConverter.write(AbstractHttpMessageConverter.java:208)
    at org.springframework.web.servlet.mvc.method.annotation.AbstractMessageConverterMethodProcessor.writeWithMessageConverters(AbstractMessageConverterMethodProcessor.java:158)
    at org.springframework.web.servlet.mvc.method.annotation.HttpEntityMethodProcessor.handleReturnValue(HttpEntityMethodProcessor.java:138)
    at org.springframework.web.method.support.HandlerMethodReturnValueHandlerComposite.handleReturnValue(HandlerMethodReturnValueHandlerComposite.java:71)
    at org.springframework.web.servlet.mvc.method.annotation.ServletInvocableHandlerMethod.invokeAndHandle(ServletInvocableHandlerMethod.java:122)
    at org.springframework.web.servlet.mvc.method.annotation.RequestMappingHandlerAdapter.invokeHandleMethod(RequestMappingHandlerAdapter.java:781)
    at org.springframework.web.servlet.mvc.method.annotation.RequestMappingHandlerAdapter.handleInternal(RequestMappingHandlerAdapter.java:721)
    at org.springframework.web.servlet.mvc.method.AbstractHandlerMethodAdapter.handle(AbstractHandlerMethodAdapter.java:83)
    at org.springframework.web.servlet.DispatcherServlet.doDispatch(DispatcherServlet.java:943)
    at org.springframework.web.servlet.DispatcherServlet.doService(DispatcherServlet.java:877)
    at org.springframework.web.servlet.FrameworkServlet.processRequest(FrameworkServlet.java:966)
    at org.springframework.web.servlet.FrameworkServlet.doGet(FrameworkServlet.java:857)
    at javax.servlet.http.HttpServlet.service(HttpServlet.java:620)
    at org.springframework.web.servlet.FrameworkServlet.service(FrameworkServlet.java:842)
    at javax.servlet.http.HttpServlet.service(HttpServlet.java:727)
    at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:303)
    at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:208)
    at org.springframework.web.filter.HiddenHttpMethodFilter.doFilterInternal(HiddenHttpMethodFilter.java:77)
    at org.springframework.web.filter.OncePerRequestFilter.doFilter(OncePerRequestFilter.java:107)
    at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:241)
    at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:208)
    at org.apache.tomcat.websocket.server.WsFilter.doFilter(WsFilter.java:52)
    at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:241)
    at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:208)
    at org.springframework.security.web.FilterChainProxy$VirtualFilterChain.doFilter(FilterChainProxy.java:330)
    at org.springframework.security.web.access.intercept.FilterSecurityInterceptor.invoke(FilterSecurityInterceptor.java:118)
    at org.springframework.security.web.access.intercept.FilterSecurityInterceptor.doFilter(FilterSecurityInterceptor.java:84)
    at org.springframework.security.web.FilterChainProxy$VirtualFilterChain.doFilter(FilterChainProxy.java:342)
    at org.springframework.security.web.access.ExceptionTranslationFilter.doFilter(ExceptionTranslationFilter.java:113)
    at org.springframework.security.web.FilterChainProxy$VirtualFilterChain.doFilter(FilterChainProxy.java:342)
    at org.springframework.security.web.session.SessionManagementFilter.doFilter(SessionManagementFilter.java:103)
    at org.springframework.security.web.FilterChainProxy$VirtualFilterChain.doFilter(FilterChainProxy.java:342)
    at org.springframework.security.web.authentication.AnonymousAuthenticationFilter.doFilter(AnonymousAuthenticationFilter.java:113)
    at org.springframework.security.web.FilterChainProxy$VirtualFilterChain.doFilter(FilterChainProxy.java:342)
    at org.springframework.security.web.servletapi.SecurityContextHolderAwareRequestFilter.doFilter(SecurityContextHolderAwareRequestFilter.java:154)
    at org.springframework.security.web.FilterChainProxy$VirtualFilterChain.doFilter(FilterChainProxy.java:342)
    at org.springframework.security.web.savedrequest.RequestCacheAwareFilter.doFilter(RequestCacheAwareFilter.java:45)
    at org.springframework.security.web.FilterChainProxy$VirtualFilterChain.doFilter(FilterChainProxy.java:342)
    at org.springframework.security.web.authentication.www.BasicAuthenticationFilter.doFilter(BasicAuthenticationFilter.java:150)
    at org.springframework.security.web.FilterChainProxy$VirtualFilterChain.doFilter(FilterChainProxy.java:342)
    at org.springframework.security.web.authentication.ui.DefaultLoginPageGeneratingFilter.doFilter(DefaultLoginPageGeneratingFilter.java:155)
    at org.springframework.security.web.FilterChainProxy$VirtualFilterChain.doFilter(FilterChainProxy.java:342)
    at org.springframework.security.web.authentication.AbstractAuthenticationProcessingFilter.doFilter(AbstractAuthenticationProcessingFilter.java:199)
    at org.springframework.security.web.FilterChainProxy$VirtualFilterChain.doFilter(FilterChainProxy.java:342)
    at org.springframework.security.web.authentication.logout.LogoutFilter.doFilter(LogoutFilter.java:110)
    at org.springframework.security.web.FilterChainProxy$VirtualFilterChain.doFilter(FilterChainProxy.java:342)
    at org.springframework.security.web.context.request.async.WebAsyncManagerIntegrationFilter.doFilterInternal(WebAsyncManagerIntegrationFilter.java:50)
    at org.springframework.web.filter.OncePerRequestFilter.doFilter(OncePerRequestFilter.java:107)
    at org.springframework.security.web.FilterChainProxy$VirtualFilterChain.doFilter(FilterChainProxy.java:342)
    at org.springframework.security.web.context.SecurityContextPersistenceFilter.doFilter(SecurityContextPersistenceFilter.java:87)
    at org.springframework.security.web.FilterChainProxy$VirtualFilterChain.doFilter(FilterChainProxy.java:342)
    at org.springframework.security.web.FilterChainProxy.doFilterInternal(FilterChainProxy.java:192)
    at org.springframework.security.web.FilterChainProxy.doFilter(FilterChainProxy.java:160)
    at org.springframework.web.filter.DelegatingFilterProxy.invokeDelegate(DelegatingFilterProxy.java:344)
    at org.springframework.web.filter.DelegatingFilterProxy.doFilter(DelegatingFilterProxy.java:261)
    at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:241)
    at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:208)
    at org.apache.catalina.core.StandardWrapperValve.invoke(StandardWrapperValve.java:220)
    at org.apache.catalina.core.StandardContextValve.invoke(StandardContextValve.java:122)
    at org.apache.catalina.authenticator.AuthenticatorBase.invoke(AuthenticatorBase.java:501)
    at org.apache.catalina.core.StandardHostValve.invoke(StandardHostValve.java:171)
    at org.apache.catalina.valves.ErrorReportValve.invoke(ErrorReportValve.java:102)
    at org.apache.catalina.valves.AccessLogValve.invoke(AccessLogValve.java:950)
    at org.apache.catalina.core.StandardEngineValve.invoke(StandardEngineValve.java:116)
    at org.apache.catalina.connector.CoyoteAdapter.service(CoyoteAdapter.java:408)
    at org.apache.coyote.http11.AbstractHttp11Processor.process(AbstractHttp11Processor.java:1040)
    at org.apache.coyote.AbstractProtocol$AbstractConnectionHandler.process(AbstractProtocol.java:607)
    at org.apache.tomcat.util.net.JIoEndpoint$SocketProcessor.run(JIoEndpoint.java:314)
    at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1145)
    at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:615)
    at org.apache.tomcat.util.threads.TaskThread$WrappingRunnable.run(TaskThread.java:61)
    at java.lang.Thread.run(Thread.java:745)
Caused by: com.fasterxml.jackson.databind.JsonMappingException: 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: net.jkratz.igdb.model.ESRBRating_$$_jvstb5c_0["handler"])
    at com.fasterxml.jackson.databind.ser.impl.UnknownSerializer.failForEmpty(UnknownSerializer.java:59)
    at com.fasterxml.jackson.databind.ser.impl.UnknownSerializer.serialize(UnknownSerializer.java:26)
    at com.fasterxml.jackson.databind.ser.BeanPropertyWriter.serializeAsField(BeanPropertyWriter.java:505)
    at com.fasterxml.jackson.databind.ser.std.BeanSerializerBase.serializeFields(BeanSerializerBase.java:639)
    at com.fasterxml.jackson.databind.ser.BeanSerializer.serialize(BeanSerializer.java:152)
    at com.fasterxml.jackson.databind.ser.DefaultSerializerProvider.serializeValue(DefaultSerializerProvider.java:114)
    at com.fasterxml.jackson.databind.ObjectMapper.writeValue(ObjectMapper.java:1887)
    at org.springframework.http.converter.json.AbstractJackson2HttpMessageConverter.writeInternal(AbstractJackson2HttpMessageConverter.java:231)
    ... 72 more

更新 2：

我最终将 @Proxy(lazy = false) 放在 ESRBRating 类上，现在它可以正常工作了。不过我很好奇这会对性能产生什么样的影响？

@Entity
@Table(name = "esrb_rating", schema = "igdb")
@JsonIgnoreProperties(ignoreUnknown = false)
@Proxy(lazy = false)
public class ESRBRating implements Serializable 

    private static final long serialVersionUID = 1L;

    @Id
    @NotNull
    @GeneratedValue(strategy = GenerationType.AUTO)
    @Column(name = "id", nullable = false)
    private Long id;

    @NotNull
    @Size(min = 1, max = 255)
    @Column(name = "title", nullable = false, length = 255)
    private String title;

    @Size(max = 65535)
    @Column(length = 65535)
    private String description;

    @OneToMany(cascade = CascadeType.ALL, mappedBy = "esrbRating")
    private List<Game> games;

    public ESRBRating() 
    

    public ESRBRating(Long id, String title, String description) 
        this.id = id;
        this.title = title;
        this.description = description;
    

    public Long getId() 
        return id;
    

    public void setId(Long id) 
        this.id = id;
    

    public String getTitle() 
        return title;
    

    public void setTitle(String title) 
        this.title = title;
    

    public String getDescription() 
        return description;
    

    public void setDescription(String description) 
        this.description = description;
    


    @JsonIgnore
    public List<Game> getGames() 
        return games;
    

    public void setGames(List<Game> games) 
        this.games = games;
    

    @Override
    public boolean equals(Object o) 
        if (this == o) return true;
        if (o == null || getClass() != o.getClass()) return false;

        ESRBRating that = (ESRBRating) o;

        return Objects.equal(this.id, that.id) &&
                Objects.equal(this.title, that.title) &&
                Objects.equal(this.description, that.description);
    

    @Override
    public int hashCode() 
        return Objects.hashCode(id, title, description);
    

    @Override
    public String toString() 
        return Objects.toStringHelper(this)
                .add("id", id)
                .add("title", title)
                .add("description", description)
                .toString();
    

这里要求的是游戏类

@Entity
@Table(name = "game", schema = "igdb",
        indexes = @Index(name = "idx_game_title", columnList = ("title"), unique = false),
                @Index(name = "idx_game_developer", columnList = ("developer"), unique = false),
                @Index(name = "idx_game_publisher", columnList = ("publisher"), unique = false))
@JsonIgnoreProperties(ignoreUnknown = true)
public class Game implements Serializable 

    private static final long serialVersionUID = 1L;

    @Id
    @NotNull
    @GeneratedValue(strategy = GenerationType.AUTO)
    @Column(name = "id", nullable = false)
    private Long id;

    @NotNull
    @Size(min = 1, max = 255)
    @Column(name = "title", nullable = false, length = 255)
    private String title;

    @Size(max = 65535)
    @Column(name = "description", length = 65535)
    private String description;

    @Size(max = 255)
    @Column(name = "developer", length = 255)
    private String developer;

    @Size(max = 255)
    @Column(name = "publisher", length = 255)
    private String publisher;

    @NotNull
    @Size(max = 4)
    @Column(name = "players", nullable = false)
    private short players;

    @NotNull
    @Column(name = "cooperative", nullable = false)
    private boolean cooperative;

    @NotNull
    @Column(name = "release_date", nullable = false)
    @Temporal(TemporalType.DATE)
    private Date releaseDate;

    @Size(max = 255)
    @Column(name = "image", length = 255)
    private String image;

    @JoinColumn(name = "esrb_rating_id", referencedColumnName = "id", nullable = false)
    @ManyToOne(optional = false, fetch = FetchType.EAGER)
    private ESRBRating esrbRating;   

    @OneToMany(cascade = CascadeType.ALL, mappedBy = "game")
    private List<GamePlatformMap> gamePlatformMap;

    @OneToMany(cascade = CascadeType.ALL, mappedBy = "game")
    private List<GameGenreMap> gameGenreMap;

    public Game() 

    

    public Game(Long id, String title, String description, String developer,
            String publisher, short players, boolean cooperative,
            Date releaseDate, String image, ESRBRating esrbRating) 
        super();
        this.id = id;
        this.title = title;
        this.description = description;
        this.developer = developer;
        this.publisher = publisher;
        this.players = players;
        this.cooperative = cooperative;
        this.releaseDate = releaseDate;
        this.image = image;
        this.esrbRating = esrbRating;
    

    public Long getId() 
        return id;
    

    public void setId(Long id) 
        this.id = id;
    

    public String getTitle() 
        return title;
    

    public void setTitle(String title) 
        this.title = title;
    

    public String getDescription() 
        return description;
    

    public void setDescription(String description) 
        this.description = description;
    

    public String getDeveloper() 
        return developer;
    

    public void setDeveloper(String developer) 
        this.developer = developer;
    

    public String getPublisher() 
        return publisher;
    

    public void setPublisher(String publisher) 
        this.publisher = publisher;
    

    public short getPlayers() 
        return players;
    

    public void setPlayers(short players) 
        this.players = players;
    

    public boolean isCooperative() 
        return cooperative;
    

    public void setCooperative(boolean cooperative) 
        this.cooperative = cooperative;
    

    public Date getReleaseDate() 
        return releaseDate;
    

    public void setReleaseDate(Date releaseDate) 
        this.releaseDate = releaseDate;
    

    public String getImage() 
        return image;
    

    public void setImage(String image) 
        this.image = image;
    

    public ESRBRating getEsrbRating() 
        return esrbRating;
    

    public void setEsrbRating(ESRBRating esrbRating) 
        this.esrbRating = esrbRating;
    

    @JsonIgnore
    public List<GamePlatformMap> getGamePlatformMap() 
        return gamePlatformMap;
    

    public void setGamePlatformMap(List<GamePlatformMap> gamePlatformMap) 
        this.gamePlatformMap = gamePlatformMap;
    

    @JsonIgnore
    public List<GameGenreMap> getGameGenreMap() 
        return gameGenreMap;
    

    public void setGameGenreMap(List<GameGenreMap> gameGenreMap) 
        this.gameGenreMap = gameGenreMap;
    

    @Override
    public boolean equals(Object o) 
        if (this == o) return true;
        if (o == null || getClass() != o.getClass()) return false;

        Game that = (Game) o;

        return Objects.equal(this.id, that.id) &&
                Objects.equal(this.title, that.title) &&
                Objects.equal(this.description, that.description) &&
                Objects.equal(this.developer, that.developer) &&
                Objects.equal(this.publisher, that.publisher) &&
                Objects.equal(this.players, that.players) &&
                Objects.equal(this.cooperative, that.cooperative) &&
                Objects.equal(this.releaseDate, that.releaseDate) &&
                Objects.equal(this.image, that.image) &&
                Objects.equal(this.esrbRating, that.esrbRating);
    

    @Override
    public int hashCode() 
        return Objects.hashCode(id, title, description, developer, publisher, players,
                cooperative, releaseDate, image, esrbRating);
    

    @Override
    public String toString() 
        return Objects.toStringHelper(this)
                .add("id", id)
                .add("title", title)
                .add("description", description)
                .add("developer", developer)
                .add("publisher", publisher)
                .add("players", players)
                .add("cooperative", cooperative)
                .add("releaseDate", releaseDate)
                .add("image", image)
                .add("esrbRating", esrbRating)
                .toString();
    

【问题讨论】：

@Proxy(lazy = false) 谢谢。

@André Luís Tomaz Dionisio - 谢谢！你的建议就行了:)

类似于***.com/questions/21708339/…

【参考方案1】：

我遇到了同样的错误，但没有答案帮助我。

看来问题出在jpa.open-in-view=false。我已将其删除，现在一切正常。

【参考方案2】：

解决了 Spring Boot 2.3.0 通过添加到 gradle.build:

实现'com.fasterxml.jackson.datatype:jackson-datatype-hibernate5:2.11.3'

再声明一个 bean：

@Bean
public Module datatypeHibernateModule() 
    return new Hibernate5Module();

【参考方案3】：

@JsonIgnore 注释可能会解决您的问题，但它会导致您最初设置为 FetchType.LAZY 的特定字段被完全忽略。这里给出了一个更好的选择 https://***.com/a/21760361/3609067

【参考方案4】：

首先根据jackson-core版本下载jackson-datatype-hibernate4-2.2.3.jar或更高版本。然后在配置文件中使用此代码，您可以使用 fetch strategy LAZY 而不会出现任何错误。

import com.fasterxml.jackson.databind.ObjectMapper;
import com.fasterxml.jackson.datatype.hibernate4.Hibernate4Module;


public class ApplicationConfig extends WebMvcConfigurerAdapter

public MappingJackson2HttpMessageConverter jacksonMessageConverter()
    MappingJackson2HttpMessageConverter messageConverter = new  MappingJackson2HttpMessageConverter();

    ObjectMapper mapper = new ObjectMapper();
    //Registering Hibernate4Module to support lazy objects
    mapper.registerModule(new Hibernate4Module());

    messageConverter.setObjectMapper(mapper);
    return messageConverter;



@Override
public void configureMessageConverters(List<HttpMessageConverter<?>> converters) 
    //Here we add our custom-configured HttpMessageConverter
    converters.add(jacksonMessageConverter());
    super.configureMessageConverters(converters);

【参考方案5】：

这通常发生在您通过@Responsebody（或者在您的情况下通过@RestController）返回一个对象并且一个对象正在被序列化但在一个尚未被引用的LAZY集合中具有子级时。当你在你的控制器中时，不再有一个事务处于活动状态，这将有助于它们被获取（就像你在 @Service 中启动的那样）。您可以使您的获取策略 EAGER，在您的事务中通过引用引入您的集合，或者使您的 LAZY 集合为 JSON 瞬态。

【讨论】：

好的，所以@JsonIgnore 处理了未初始化的集合，但是现在我收到关于序列化的错误。关于我最新的堆栈跟踪的任何想法。我用详细信息更新了我的问题。

这通常是因为想要被序列化的类有私有字段而没有公共 getter 和 setter。这似乎不是这里的情况。还有——游戏在哪里？在我们尝试调试它之前遇到很多麻烦，只是为了笑，将@JsonSerialize 放在 ESRBRating 的类声明上。另外，请接受我对第一个问题的回答。

如果您使用的是后来的 Jackson，它将是 @JsonInclude(Include.NON_NULL)

我更新了我的问题。 JsonInclude 和 JsonSerialize 没有区别。不知何故，我又回到了奇怪的原始堆栈跟踪。我做了一些研究，发现@Proxy(lazy = false)。在我将它添加到 ESRBRating 类之后，它开始正常工作。但是我不确定这会对应用程序产生什么样的影响（性能、内存消耗等）