json - 使用 Spring Boot 和 Hibernate 的 Jackson - 使用 @JsonIdentityInfo 从 Id 创建对象

Question

我正在使用 Spring 和 Hibernate。以下是我的通知实体。

Notice.java

package com.college.model;

import java.util.Date;
import java.util.Set;

import javax.persistence.Column;
import javax.persistence.Entity;
import javax.persistence.EntityListeners;
import javax.persistence.FetchType;
import javax.persistence.GeneratedValue;
import javax.persistence.GenerationType;
import javax.persistence.Id;
import javax.persistence.JoinColumn;
import javax.persistence.ManyToOne;
import javax.persistence.OneToMany;
import javax.persistence.Temporal;
import javax.persistence.TemporalType;

import org.springframework.data.annotation.CreatedBy;
import org.springframework.data.annotation.CreatedDate;
import org.springframework.data.annotation.LastModifiedBy;
import org.springframework.data.annotation.LastModifiedDate;
import org.springframework.data.jpa.domain.support.AuditingEntityListener;

import com.fasterxml.jackson.annotation.JsonIdentityInfo;
import com.fasterxml.jackson.annotation.JsonIdentityReference;
import com.fasterxml.jackson.annotation.ObjectIdGenerators;

@Entity
@EntityListeners(AuditingEntityListener.class)
@JsonIdentityInfo(generator=ObjectIdGenerators.PropertyGenerator.class, property="id")
public class Notice {

    @Id
    @GeneratedValue(strategy = GenerationType.AUTO)
    private Long id;

    @CreatedDate
    @Column(name="DATE_CREATED")
    @Temporal(TemporalType.TIMESTAMP)
    private Date createdDate;

    @LastModifiedDate 
    @Column(name="LAST_UPDATED")
    @Temporal(TemporalType.TIMESTAMP)
    private Date lastModifiedDate;


    @CreatedBy
    @ManyToOne(fetch = FetchType.LAZY)
    @JoinColumn(name="CREATED_BY")
    private User createdBy;

    @LastModifiedBy
    @ManyToOne(fetch = FetchType.LAZY)
    @JoinColumn(name="LAST_MODIFIED_BY")
    private User lastModifiedBy;

    private String title;

    private String description;

    @ManyToOne
    @JoinColumn(name = "DEPT_ID")
    private Department department;

    public Long getId() {
        return id;
    }

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

    public Date getCreatedDate() {
        return createdDate;
    }

    public void setCreatedDate(Date createdDate) {
        this.createdDate = createdDate;
    }

    public Date getLastModifiedDate() {
        return lastModifiedDate;
    }

    public void setLastModifiedDate(Date lastModifiedDate) {
        this.lastModifiedDate = lastModifiedDate;
    }

    public User getCreatedBy() {
        return createdBy;
    }

    public void setCreatedBy(User createdBy) {
        this.createdBy = createdBy;
    }

    public User getLastModifiedBy() {
        return lastModifiedBy;
    }

    public void setLastModifiedBy(User lastModifiedBy) {
        this.lastModifiedBy = lastModifiedBy;
    }

    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 Department getDepartment() {
        return department;
    }

    public void setDepartment(Department department) {
        this.department = department;
    }   

}

可以看到，Notice属于Department，具有ManyToOne关系。当我尝试通过发布 json 创建通知时，它给出了以下异常:

异常:

org.springframework.http.converter.HttpMessageNotReadableException: Could not read document: Unresolved forward references for: Object id [1] (for com.college.model.Department) at [Source: java.io.PushbackInputStream@1b71179f; line: 1, column: 13].; nested exception is com.fasterxml.jackson.databind.deser.UnresolvedForwardReference: Unresolved forward references for: Object id [1] (for com.college.model.Department) at [Source: java.io.PushbackInputStream@1b71179f; line: 1, column: 13].
    at org.springframework.http.converter.json.AbstractJackson2HttpMessageConverter.readJavaType(AbstractJackson2HttpMessageConverter.java:225) ~[spring-web-4.2.5.RELEASE.jar:4.2.5.RELEASE]
    at org.springframework.http.converter.json.AbstractJackson2HttpMessageConverter.read(AbstractJackson2HttpMessageConverter.java:209) ~[spring-web-4.2.5.RELEASE.jar:4.2.5.RELEASE]
    at org.springframework.web.servlet.mvc.method.annotation.AbstractMessageConverterMethodArgumentResolver.readWithMessageConverters(AbstractMessageConverterMethodArgumentResolver.java:197) ~[spring-webmvc-4.2.5.RELEASE.jar:4.2.5.RELEASE]
    at org.springframework.web.servlet.mvc.method.annotation.RequestResponseBodyMethodProcessor.readWithMessageConverters(RequestResponseBodyMethodProcessor.java:147) ~[spring-webmvc-4.2.5.RELEASE.jar:4.2.5.RELEASE]
    at org.springframework.web.servlet.mvc.method.annotation.RequestResponseBodyMethodProcessor.resolveArgument(RequestResponseBodyMethodProcessor.java:125) ~[spring-webmvc-4.2.5.RELEASE.jar:4.2.5.RELEASE]
    at org.springframework.web.method.support.HandlerMethodArgumentResolverComposite.resolveArgument(HandlerMethodArgumentResolverComposite.java:99) ~[spring-web-4.2.5.RELEASE.jar:4.2.5.RELEASE]
    at org.springframework.web.method.support.InvocableHandlerMethod.getMethodArgumentValues(InvocableHandlerMethod.java:161) [spring-web-4.2.5.RELEASE.jar:4.2.5.RELEASE]
    at org.springframework.web.method.support.InvocableHandlerMethod.invokeForRequest(InvocableHandlerMethod.java:128) [spring-web-4.2.5.RELEASE.jar:4.2.5.RELEASE]
    at org.springframework.web.servlet.mvc.method.annotation.ServletInvocableHandlerMethod.invokeAndHandle(ServletInvocableHandlerMethod.java:110) [spring-webmvc-4.2.5.RELEASE.jar:4.2.5.RELEASE]
    at org.springframework.web.servlet.mvc.method.annotation.RequestMappingHandlerAdapter.invokeHandlerMethod(RequestMappingHandlerAdapter.java:817) [spring-webmvc-4.2.5.RELEASE.jar:4.2.5.RELEASE]
    at org.springframework.web.servlet.mvc.method.annotation.RequestMappingHandlerAdapter.handleInternal(RequestMappingHandlerAdapter.java:731) [spring-webmvc-4.2.5.RELEASE.jar:4.2.5.RELEASE]
    at org.springframework.web.servlet.mvc.method.AbstractHandlerMethodAdapter.handle(AbstractHandlerMethodAdapter.java:85) [spring-webmvc-4.2.5.RELEASE.jar:4.2.5.RELEASE]
    at org.springframework.web.servlet.DispatcherServlet.doDispatch(DispatcherServlet.java:959) [spring-webmvc-4.2.5.RELEASE.jar:4.2.5.RELEASE]
    at org.springframework.web.servlet.DispatcherServlet.doService(DispatcherServlet.java:893) [spring-webmvc-4.2.5.RELEASE.jar:4.2.5.RELEASE]
    at org.springframework.web.servlet.FrameworkServlet.processRequest(FrameworkServlet.java:968) [spring-webmvc-4.2.5.RELEASE.jar:4.2.5.RELEASE]
    at org.springframework.web.servlet.FrameworkServlet.doPost(FrameworkServlet.java:870) [spring-webmvc-4.2.5.RELEASE.jar:4.2.5.RELEASE]
    at javax.servlet.http.HttpServlet.service(HttpServlet.java:707) [javax.servlet-api-3.1.0.jar:3.1.0]
    at org.springframework.web.servlet.FrameworkServlet.service(FrameworkServlet.java:844) [spring-webmvc-4.2.5.RELEASE.jar:4.2.5.RELEASE]
    at javax.servlet.http.HttpServlet.service(HttpServlet.java:790) [javax.servlet-api-3.1.0.jar:3.1.0]
    at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:292) [tomcat-embed-core-8.0.32.jar:8.0.32]
    at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:207) [tomcat-embed-core-8.0.32.jar:8.0.32]
    at org.apache.tomcat.websocket.server.WsFilter.doFilter(WsFilter.java:52) [tomcat-embed-websocket-8.0.32.jar:8.0.32]
    at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:240) [tomcat-embed-core-8.0.32.jar:8.0.32]
    at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:207) [tomcat-embed-core-8.0.32.jar:8.0.32]
    at org.springframework.boot.actuate.autoconfigure.EndpointWebMvcAutoConfiguration$ApplicationContextHeaderFilter.doFilterInternal(EndpointWebMvcAutoConfiguration.java:237) [spring-boot-actuator-1.3.3.RELEASE.jar:1.3.3.RELEASE]
    at org.springframework.web.filter.OncePerRequestFilter.doFilter(OncePerRequestFilter.java:107) [spring-web-4.2.5.RELEASE.jar:4.2.5.RELEASE]
    at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:240) [tomcat-embed-core-8.0.32.jar:8.0.32]
    at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:207) [tomcat-embed-core-8.0.32.jar:8.0.32]
    at org.springframework.boot.actuate.trace.WebRequestTraceFilter.doFilterInternal(WebRequestTraceFilter.java:112) [spring-boot-actuator-1.3.3.RELEASE.jar:1.3.3.RELEASE]
    at org.springframework.web.filter.OncePerRequestFilter.doFilter(OncePerRequestFilter.java:107) [spring-web-4.2.5.RELEASE.jar:4.2.5.RELEASE]
    at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:240) [tomcat-embed-core-8.0.32.jar:8.0.32]
    at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:207) [tomcat-embed-core-8.0.32.jar:8.0.32]
    at org.springframework.security.web.FilterChainProxy$VirtualFilterChain.doFilter(FilterChainProxy.java:316) [spring-security-web-4.0.3.RELEASE.jar:4.0.3.RELEASE]
    at org.springframework.security.web.access.intercept.FilterSecurityInterceptor.invoke(FilterSecurityInterceptor.java:126) [spring-security-web-4.0.3.RELEASE.jar:4.0.3.RELEASE]
    at org.springframework.security.web.access.intercept.FilterSecurityInterceptor.doFilter(FilterSecurityInterceptor.java:90) [spring-security-web-4.0.3.RELEASE.jar:4.0.3.RELEASE]
    at org.springframework.security.web.FilterChainProxy$VirtualFilterChain.doFilter(FilterChainProxy.java:330) [spring-security-web-4.0.3.RELEASE.jar:4.0.3.RELEASE]
    at org.springframework.security.web.access.ExceptionTranslationFilter.doFilter(ExceptionTranslationFilter.java:114) [spring-security-web-4.0.3.RELEASE.jar:4.0.3.RELEASE]
    at org.springframework.security.web.FilterChainProxy$VirtualFilterChain.doFilter(FilterChainProxy.java:330) [spring-security-web-4.0.3.RELEASE.jar:4.0.3.RELEASE]
    at org.springframework.security.web.session.SessionManagementFilter.doFilter(SessionManagementFilter.java:122) [spring-security-web-4.0.3.RELEASE.jar:4.0.3.RELEASE]
    at org.springframework.security.web.FilterChainProxy$VirtualFilterChain.doFilter(FilterChainProxy.java:330) [spring-security-web-4.0.3.RELEASE.jar:4.0.3.RELEASE]
    at org.springframework.security.web.authentication.AnonymousAuthenticationFilter.doFilter(AnonymousAuthenticationFilter.java:111) [spring-security-web-4.0.3.RELEASE.jar:4.0.3.RELEASE]
    at org.springframework.security.web.FilterChainProxy$VirtualFilterChain.doFilter(FilterChainProxy.java:330) [spring-security-web-4.0.3.RELEASE.jar:4.0.3.RELEASE]
    at org.springframework.security.web.servletapi.SecurityContextHolderAwareRequestFilter.doFilter(SecurityContextHolderAwareRequestFilter.java:169) [spring-security-web-4.0.3.RELEASE.jar:4.0.3.RELEASE]
    at org.springframework.security.web.FilterChainProxy$VirtualFilterChain.doFilter(FilterChainProxy.java:330) [spring-security-web-4.0.3.RELEASE.jar:4.0.3.RELEASE]
    at org.springframework.security.web.savedrequest.RequestCacheAwareFilter.doFilter(RequestCacheAwareFilter.java:48) [spring-security-web-4.0.3.RELEASE.jar:4.0.3.RELEASE]
    at org.springframework.security.web.FilterChainProxy$VirtualFilterChain.doFilter(FilterChainProxy.java:330) [spring-security-web-4.0.3.RELEASE.jar:4.0.3.RELEASE]
    at org.springframework.security.web.authentication.AbstractAuthenticationProcessingFilter.doFilter(AbstractAuthenticationProcessingFilter.java:205) [spring-security-web-4.0.3.RELEASE.jar:4.0.3.RELEASE]
    at org.springframework.security.web.FilterChainProxy$VirtualFilterChain.doFilter(FilterChainProxy.java:330) [spring-security-web-4.0.3.RELEASE.jar:4.0.3.RELEASE]
    at org.springframework.security.web.authentication.logout.LogoutFilter.doFilter(LogoutFilter.java:120) [spring-security-web-4.0.3.RELEASE.jar:4.0.3.RELEASE]
    at org.springframework.security.web.FilterChainProxy$VirtualFilterChain.doFilter(FilterChainProxy.java:330) [spring-security-web-4.0.3.RELEASE.jar:4.0.3.RELEASE]
    at com.college.config.SecurityConfiguration$1.doFilterInternal(SecurityConfiguration.java:134) [bin/:na]
    at org.springframework.web.filter.OncePerRequestFilter.doFilter(OncePerRequestFilter.java:107) [spring-web-4.2.5.RELEASE.jar:4.2.5.RELEASE]
    at org.springframework.security.web.FilterChainProxy$VirtualFilterChain.doFilter(FilterChainProxy.java:330) [spring-security-web-4.0.3.RELEASE.jar:4.0.3.RELEASE]
    at org.springframework.security.web.csrf.CsrfFilter.doFilterInternal(CsrfFilter.java:120) [spring-security-web-4.0.3.RELEASE.jar:4.0.3.RELEASE]
    at org.springframework.web.filter.OncePerRequestFilter.doFilter(OncePerRequestFilter.java:107) [spring-web-4.2.5.RELEASE.jar:4.2.5.RELEASE]
    at org.springframework.security.web.FilterChainProxy$VirtualFilterChain.doFilter(FilterChainProxy.java:330) [spring-security-web-4.0.3.RELEASE.jar:4.0.3.RELEASE]
    at org.springframework.security.web.header.HeaderWriterFilter.doFilterInternal(HeaderWriterFilter.java:64) [spring-security-web-4.0.3.RELEASE.jar:4.0.3.RELEASE]
    at org.springframework.web.filter.OncePerRequestFilter.doFilter(OncePerRequestFilter.java:107) [spring-web-4.2.5.RELEASE.jar:4.2.5.RELEASE]
    at org.springframework.security.web.FilterChainProxy$VirtualFilterChain.doFilter(FilterChainProxy.java:330) [spring-security-web-4.0.3.RELEASE.jar:4.0.3.RELEASE]
    at org.springframework.security.web.context.SecurityContextPersistenceFilter.doFilter(SecurityContextPersistenceFilter.java:91) [spring-security-web-4.0.3.RELEASE.jar:4.0.3.RELEASE]
    at org.springframework.security.web.FilterChainProxy$VirtualFilterChain.doFilter(FilterChainProxy.java:330) [spring-security-web-4.0.3.RELEASE.jar:4.0.3.RELEASE]
    at org.springframework.security.web.context.request.async.WebAsyncManagerIntegrationFilter.doFilterInternal(WebAsyncManagerIntegrationFilter.java:53) [spring-security-web-4.0.3.RELEASE.jar:4.0.3.RELEASE]
    at org.springframework.web.filter.OncePerRequestFilter.doFilter(OncePerRequestFilter.java:107) [spring-web-4.2.5.RELEASE.jar:4.2.5.RELEASE]
    at org.springframework.security.web.FilterChainProxy$VirtualFilterChain.doFilter(FilterChainProxy.java:330) [spring-security-web-4.0.3.RELEASE.jar:4.0.3.RELEASE]
    at org.springframework.security.web.FilterChainProxy.doFilterInternal(FilterChainProxy.java:213) [spring-security-web-4.0.3.RELEASE.jar:4.0.3.RELEASE]
    at org.springframework.security.web.FilterChainProxy.doFilter(FilterChainProxy.java:176) [spring-security-web-4.0.3.RELEASE.jar:4.0.3.RELEASE]
    at org.springframework.web.filter.DelegatingFilterProxy.invokeDelegate(DelegatingFilterProxy.java:346) [spring-web-4.2.5.RELEASE.jar:4.2.5.RELEASE]
    at org.springframework.web.filter.DelegatingFilterProxy.doFilter(DelegatingFilterProxy.java:262) [spring-web-4.2.5.RELEASE.jar:4.2.5.RELEASE]
    at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:240) [tomcat-embed-core-8.0.32.jar:8.0.32]
    at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:207) [tomcat-embed-core-8.0.32.jar:8.0.32]
    at org.springframework.web.filter.RequestContextFilter.doFilterInternal(RequestContextFilter.java:99) [spring-web-4.2.5.RELEASE.jar:4.2.5.RELEASE]
    at org.springframework.web.filter.OncePerRequestFilter.doFilter(OncePerRequestFilter.java:107) [spring-web-4.2.5.RELEASE.jar:4.2.5.RELEASE]
    at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:240) [tomcat-embed-core-8.0.32.jar:8.0.32]
    at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:207) [tomcat-embed-core-8.0.32.jar:8.0.32]
    at org.springframework.web.filter.CharacterEncodingFilter.doFilterInternal(CharacterEncodingFilter.java:121) [spring-web-4.2.5.RELEASE.jar:4.2.5.RELEASE]
    at org.springframework.web.filter.OncePerRequestFilter.doFilter(OncePerRequestFilter.java:107) [spring-web-4.2.5.RELEASE.jar:4.2.5.RELEASE]
    at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:240) [tomcat-embed-core-8.0.32.jar:8.0.32]
    at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:207) [tomcat-embed-core-8.0.32.jar:8.0.32]
    at org.springframework.boot.actuate.autoconfigure.MetricsFilter.doFilterInternal(MetricsFilter.java:103) [spring-boot-actuator-1.3.3.RELEASE.jar:1.3.3.RELEASE]
    at org.springframework.web.filter.OncePerRequestFilter.doFilter(OncePerRequestFilter.java:107) [spring-web-4.2.5.RELEASE.jar:4.2.5.RELEASE]
    at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:240) [tomcat-embed-core-8.0.32.jar:8.0.32]
    at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:207) [tomcat-embed-core-8.0.32.jar:8.0.32]
    at org.apache.catalina.core.StandardWrapperValve.invoke(StandardWrapperValve.java:212) [tomcat-embed-core-8.0.32.jar:8.0.32]
    at org.apache.catalina.core.StandardContextValve.invoke(StandardContextValve.java:106) [tomcat-embed-core-8.0.32.jar:8.0.32]
    at org.apache.catalina.authenticator.AuthenticatorBase.invoke(AuthenticatorBase.java:502) [tomcat-embed-core-8.0.32.jar:8.0.32]
    at org.apache.catalina.core.StandardHostValve.invoke(StandardHostValve.java:141) [tomcat-embed-core-8.0.32.jar:8.0.32]
    at org.apache.catalina.valves.ErrorReportValve.invoke(ErrorReportValve.java:79) [tomcat-embed-core-8.0.32.jar:8.0.32]
    at org.apache.catalina.core.StandardEngineValve.invoke(StandardEngineValve.java:88) [tomcat-embed-core-8.0.32.jar:8.0.32]
    at org.apache.catalina.connector.CoyoteAdapter.service(CoyoteAdapter.java:522) [tomcat-embed-core-8.0.32.jar:8.0.32]
    at org.apache.coyote.http11.AbstractHttp11Processor.process(AbstractHttp11Processor.java:1095) [tomcat-embed-core-8.0.32.jar:8.0.32]
    at org.apache.coyote.AbstractProtocol$AbstractConnectionHandler.process(AbstractProtocol.java:672) [tomcat-embed-core-8.0.32.jar:8.0.32]
    at org.apache.tomcat.util.net.NioEndpoint$SocketProcessor.doRun(NioEndpoint.java:1500) [tomcat-embed-core-8.0.32.jar:8.0.32]
    at org.apache.tomcat.util.net.NioEndpoint$SocketProcessor.run(NioEndpoint.java:1456) [tomcat-embed-core-8.0.32.jar:8.0.32]
    at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1142) [na:1.8.0_77]
    at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:617) [na:1.8.0_77]
    at org.apache.tomcat.util.threads.TaskThread$WrappingRunnable.run(TaskThread.java:61) [tomcat-embed-core-8.0.32.jar:8.0.32]
    at java.lang.Thread.run(Thread.java:745) [na:1.8.0_77]
Caused by: com.fasterxml.jackson.databind.deser.UnresolvedForwardReference: Unresolved forward references for: Object id [1] (for com.college.model.Department) at [Source: java.io.PushbackInputStream@1b71179f; line: 1, column: 13].
    at com.fasterxml.jackson.databind.deser.DefaultDeserializationContext.checkUnresolvedObjectId(DefaultDeserializationContext.java:154) ~[jackson-databind-2.6.5.jar:2.6.5]
    at com.fasterxml.jackson.databind.ObjectMapper._readMapAndClose(ObjectMapper.java:3738) ~[jackson-databind-2.6.5.jar:2.6.5]
    at com.fasterxml.jackson.databind.ObjectMapper.readValue(ObjectMapper.java:2810) ~[jackson-databind-2.6.5.jar:2.6.5]
    at org.springframework.http.converter.json.AbstractJackson2HttpMessageConverter.readJavaType(AbstractJackson2HttpMessageConverter.java:222) ~[spring-web-4.2.5.RELEASE.jar:4.2.5.RELEASE]
    ... 96 common frames omitted

发布的JSON如下:

JSON:

{
    "department": 1,
    "description": "<p>Test Desc</p>↵",
    "title": "Test"
}

这难道不应该根据提供的 ID 工作并创建部门吗？

从 this stackoverflow question 中，我发现使用 @JsonIdentityReference 我应该能够实现这一点。但是在以 id 作为参数的 setter 方法中，我们需要 Autowiring JPA 存储库以从数据库中获取部门。而在@entity 类中，它会产生问题。

如果有人遇到类似情况，请分享。

Answer 1

解决方法:

实现 com.fasterxml.jackson.annotation.ObjectIdResolver 并在您的实体上设置为解析器:

@JsonIdentityInfo(generator = ObjectIdGenerators.PropertyGenerator.class, property = "id", resolver = UserIdResolver.class)