Question

我有一个我希望通过json rest调用公开的值对象。我在我的项目中有很多其他的休息调用工作得很好，但这1并不是出于某种原因。当我尝试将这个对象返回时 - 我得到一个例外，我不知道如何解决

值对象代码如下（减去访问者方法）

package com.test.domain.dao;

    import java.io.Serializable;
    import java.util.HashSet;
    import java.util.Set;

    import javax.persistence.Column;
    import javax.persistence.Entity;
    import javax.persistence.FetchType;
    import javax.persistence.GeneratedValue;
    import javax.persistence.GenerationType;
    import javax.persistence.Id;
    import javax.persistence.OneToMany;
    import javax.persistence.Table;

    import org.hibernate.annotations.Cascade;
    import org.hibernate.annotations.CascadeType;

    import com.fasterxml.jackson.annotation.JsonIgnore;

    @Entity
    @Table(name = "company")
    public class CompanyVO extends BaseDAOVO implements Serializable{


        /**
         * 
         */
        private static final long serialVersionUID = 4278014816235716721L;

        @Id
        @GeneratedValue(strategy = GenerationType.IDENTITY)
        @Column(name = "id", unique = true, nullable = false)
        private Integer id;

        @Column(name = "companyName", unique = true, nullable = false, length = 200)
        private String companyName;

        @Column(name = "companyLogo", unique = true, nullable = false, length = 10000)
        private String companyLogo;

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

        @OneToMany(fetch = FetchType.LAZY, mappedBy = "company")
        @Cascade({ CascadeType.DELETE, CascadeType.SAVE_UPDATE })
        @JsonIgnore
        private Set<UserVO> users = new HashSet<UserVO>(0);

    }

通过json返回公司对象的休息方法如下

/**
     * Method to get the company for a particular userId 
     * @param userId
     * @return
     */
    @RequestMapping(value = { GET_COMPANY_FOR_USER }, method = RequestMethod.GET)
    public CompanyVO getCompanyForUser(
            @PathVariable(value = RestConstants.USER_ID_PLACEHOLDER) Integer userId) {

        LOG.info("Entered getCompanyForUser method - userId:{}", userId);


        CompanyVO companyVO = companyServices.getCompanyForUser(userId);

        LOG.info("Exiting getCompanyForUser method");
        return companyVO;
    }

当我调用这个特殊的rest方法时，我在stacktrace中得到以下错误

[2015-03-02 11:12:30,229] [http-bio-8080-exec-8] [INFO] com.test.webapp.controllers.rest.CompanyRestController - Entered getCompanyForUser method - userId:1
[2015-03-02 11:12:30,248] [http-bio-8080-exec-8] [INFO] com.test.webapp.controllers.rest.CompanyRestController - Exiting getCompanyForUser method
[2015-03-02 11:12:30,267] [http-bio-8080-exec-8] [INFO] c.t.webapp.controllers.exceptions.GlobalExceptionHandlerController - Entered exception method: e:{}
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: com.test.domain.dao.CompanyVO_$$_jvstb99_6["handler"]); nested exception is com.fasterxml.jackson.databind.JsonMappingException: No serializer found for class org.hibernate.proxy.pojo.javassist.JavassistLazyInitializer and no properties discovered to create BeanSerializer (to avoid exception, disable SerializationFeature.FAIL_ON_EMPTY_BEANS) ) (through reference chain: com.test.domain.dao.CompanyVO_$$_jvstb99_6["handler"])
    at org.springframework.http.converter.json.AbstractJackson2HttpMessageConverter.writeInternal(AbstractJackson2HttpMessageConverter.java:238) ~[spring-web-4.1.4.RELEASE.jar:4.1.4.RELEASE]
    at org.springframework.http.converter.AbstractHttpMessageConverter.write(AbstractHttpMessageConverter.java:208) ~[spring-web-4.1.4.RELEASE.jar:4.1.4.RELEASE]
    at org.springframework.web.servlet.mvc.method.annotation.AbstractMessageConverterMethodProcessor.writeWithMessageConverters(AbstractMessageConverterMethodProcessor.java:161) ~[spring-webmvc-4.1.4.RELEASE.jar:4.1.4.RELEASE]
    at org.springframework.web.servlet.mvc.method.annotation.AbstractMessageConverterMethodProcessor.writeWithMessageConverters(AbstractMessageConverterMethodProcessor.java:101) ~[spring-webmvc-4.1.4.RELEASE.jar:4.1.4.RELEASE]
    at org.springframework.web.servlet.mvc.method.annotation.RequestResponseBodyMethodProcessor.handleReturnValue(RequestResponseBodyMethodProcessor.java:202) ~[spring-webmvc-4.1.4.RELEASE.jar:4.1.4.RELEASE]
    at org.springframework.web.method.support.HandlerMethodReturnValueHandlerComposite.handleReturnValue(HandlerMethodReturnValueHandlerComposite.java:71) ~[spring-web-4.1.4.RELEASE.jar:4.1.4.RELEASE]
    at org.springframework.web.servlet.mvc.method.annotation.ServletInvocableHandlerMethod.invokeAndHandle(ServletInvocableHandlerMethod.java:126) ~[spring-webmvc-4.1.4.RELEASE.jar:4.1.4.RELEASE]
    at org.springframework.web.servlet.mvc.method.annotation.RequestMappingHandlerAdapter.invokeHandleMethod(RequestMappingHandlerAdapter.java:777) ~[spring-webmvc-4.1.4.RELEASE.jar:4.1.4.RELEASE]
    at org.springframework.web.servlet.mvc.method.annotation.RequestMappingHandlerAdapter.handleInternal(RequestMappingHandlerAdapter.java:706) ~[spring-webmvc-4.1.4.RELEASE.jar:4.1.4.RELEASE]
    at org.springframework.web.servlet.mvc.method.AbstractHandlerMethodAdapter.handle(AbstractHandlerMethodAdapter.java:85) ~[spring-webmvc-4.1.4.RELEASE.jar:4.1.4.RELEASE]
    at org.springframework.web.servlet.DispatcherServlet.doDispatch(DispatcherServlet.java:943) ~[spring-webmvc-4.1.4.RELEASE.jar:4.1.4.RELEASE]
    at org.springframework.web.servlet.DispatcherServlet.doService(DispatcherServlet.java:877) ~[spring-webmvc-4.1.4.RELEASE.jar:4.1.4.RELEASE]
    at org.springframework.web.servlet.FrameworkServlet.processRequest(FrameworkServlet.java:966) [spring-webmvc-4.1.4.RELEASE.jar:4.1.4.RELEASE]
    at org.springframework.web.servlet.FrameworkServlet.doGet(FrameworkServlet.java:857) [spring-webmvc-4.1.4.RELEASE.jar:4.1.4.RELEASE]
    at javax.servlet.http.HttpServlet.service(HttpServlet.java:620) [servlet-api.jar:na]
    at org.springframework.web.servlet.FrameworkServlet.service(FrameworkServlet.java:842) [spring-webmvc-4.1.4.RELEASE.jar:4.1.4.RELEASE]
    at javax.servlet.http.HttpServlet.service(HttpServlet.java:727) [servlet-api.jar:na]
    at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:303) [catalina.jar:7.0.54]
    at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:208) [catalina.jar:7.0.54]
    at org.apache.tomcat.websocket.server.WsFilter.doFilter(WsFilter.java:52) [tomcat7-websocket.jar:7.0.54]
    at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:241) [catalina.jar:7.0.54]
    at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:208) [catalina.jar:7.0.54]
    at org.springframework.orm.hibernate4.support.OpenSessionInViewFilter.doFilterInternal(OpenSessionInViewFilter.java:150) [spring-orm-4.1.4.RELEASE.jar:4.1.4.RELEASE]
    at org.springframework.web.filter.OncePerRequestFilter.doFilter(OncePerRequestFilter.java:107) [spring-web-4.1.4.RELEASE.jar:4.1.4.RELEASE]
    at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:241) [catalina.jar:7.0.54]
    at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:208) [catalina.jar:7.0.54]
    at org.springframework.security.web.FilterChainProxy.doFilterInternal(FilterChainProxy.java:186) [spring-security-web-3.2.5.RELEASE.jar:3.2.5.RELEASE]
    at org.springframework.security.web.FilterChainProxy.doFilter(FilterChainProxy.java:160) [spring-security-web-3.2.5.RELEASE.jar:3.2.5.RELEASE]
    at org.springframework.web.filter.DelegatingFilterProxy.invokeDelegate(DelegatingFilterProxy.java:344) [spring-web-4.1.4.RELEASE.jar:4.1.4.RELEASE]
    at org.springframework.web.filter.DelegatingFilterProxy.doFilter(DelegatingFilterProxy.java:261) [spring-web-4.1.4.RELEASE.jar:4.1.4.RELEASE]
    at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:241) [catalina.jar:7.0.54]
    at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:208) [catalina.jar:7.0.54]
    at org.springframework.web.multipart.support.MultipartFilter.doFilterInternal(MultipartFilter.java:118) [spring-web-4.1.4.RELEASE.jar:4.1.4.RELEASE]
    at org.springframework.web.filter.OncePerRequestFilter.doFilter(OncePerRequestFilter.java:107) [spring-web-4.1.4.RELEASE.jar:4.1.4.RELEASE]
    at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:241) [catalina.jar:7.0.54]
    at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:208) [catalina.jar:7.0.54]
    at org.apache.catalina.core.StandardWrapperValve.invoke(StandardWrapperValve.java:220) [catalina.jar:7.0.54]
    at org.apache.catalina.core.StandardContextValve.invoke(StandardContextValve.java:122) [catalina.jar:7.0.54]
    at org.apache.catalina.authenticator.AuthenticatorBase.invoke(AuthenticatorBase.java:501) [catalina.jar:7.0.54]
    at org.apache.catalina.core.StandardHostValve.invoke(StandardHostValve.java:171) [catalina.jar:7.0.54]
    at org.apache.catalina.valves.ErrorReportValve.invoke(ErrorReportValve.java:102) [catalina.jar:7.0.54]
    at org.apache.catalina.valves.AccessLogValve.invoke(AccessLogValve.java:950) [catalina.jar:7.0.54]
    at org.apache.catalina.core.StandardEngineValve.invoke(StandardEngineValve.java:116) [catalina.jar:7.0.54]
    at org.apache.catalina.connector.CoyoteAdapter.service(CoyoteAdapter.java:408) [catalina.jar:7.0.54]
    at org.apache.coyote.http11.AbstractHttp11Processor.process(AbstractHttp11Processor.java:1040) [tomcat-coyote.jar:7.0.54]
    at org.apache.coyote.AbstractProtocol$AbstractConnectionHandler.process(AbstractProtocol.java:607) [tomcat-coyote.jar:7.0.54]
    at org.apache.tomcat.util.net.JIoEndpoint$SocketProcessor.run(JIoEndpoint.java:316) [tomcat-coyote.jar:7.0.54]
    at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1145) [na:1.7.0_40]
    at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:615) [na:1.7.0_40]
    at org.apache.tomcat.util.threads.TaskThread$WrappingRunnable.run(TaskThread.java:61) [tomcat-coyote.jar:7.0.54]
    at java.lang.Thread.run(Thread.java:724) [na:1.7.0_40]
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: com.test.domain.dao.CompanyVO_$$_jvstb99_6["handler"])
    at com.fasterxml.jackson.databind.ser.impl.UnknownSerializer.failForEmpty(UnknownSerializer.java:59) ~[jackson-databind-2.4.3.jar:2.4.3]
    at com.fasterxml.jackson.databind.ser.impl.UnknownSerializer.serialize(UnknownSerializer.java:26) ~[jackson-databind-2.4.3.jar:2.4.3]
    at com.fasterxml.jackson.databind.ser.BeanPropertyWriter.serializeAsField(BeanPropertyWriter.java:505) ~[jackson-databind-2.4.3.jar:2.4.3]
    at com.fasterxml.jackson.databind.ser.std.BeanSerializerBase.serializeFields(BeanSerializerBase.java:639) ~[jackson-databind-2.4.3.jar:2.4.3]
    at com.fasterxml.jackson.databind.ser.BeanSerializer.serialize(BeanSerializer.java:152) ~[jackson-databind-2.4.3.jar:2.4.3]
    at com.fasterxml.jackson.databind.ser.DefaultSerializerProvider.serializeValue(DefaultSerializerProvider.java:114) ~[jackson-databind-2.4.3.jar:2.4.3]
    at com.fasterxml.jackson.databind.ObjectMapper.writeValue(ObjectMapper.java:1887) ~[jackson-databind-2.4.3.jar:2.4.3]
    at org.springframework.http.converter.json.AbstractJackson2HttpMessageConverter.writeInternal(AbstractJackson2HttpMessageConverter.java:231) ~[spring-web-4.1.4.RELEASE.jar:4.1.4.RELEASE]
    ... 50 common frames omitted

非常感谢任何对此进行排序的帮助

Answer 1

除了您已经找到的解决方案之外，您还可以考虑另外两种解决方案。一个注册Hibernate4Module的 ObjectMapper ，它将注册HibernateProxySerializer，已经配备了处理代理的智能，你可以检查代码不难理解。注册也很简单，形成他们的文档：

public class HibernateAwareObjectMapper extends ObjectMapper {

    public HibernateAwareObjectMapper() {
        registerModule(new Hibernate4Module());
    }
}

而不是注册

 <mvc:annotation-driven>
        <mvc:message-converters>
            <!-- Use the HibernateAware mapper instead of the default -->
            <bean class="org.springframework.http.converter.json.MappingJackson2HttpMessageConverter">
                <property name="objectMapper">
                    <bean class="path.to.your.HibernateAwareObjectMapper" />
                </property>
            </bean>
        </mvc:message-converters>
    </mvc:annotation-driven>

另一种解决方案是使用DTO对象，在复制实体中的值时添加一些样板代码，但为您提供更多控制并将表示与实际实体分离

Answer 2

根据masterSlave提供的链接和解决方案，我将它采用到Spring Boot。我在Spring Boot项目中遇到问题并解决它以创建HibernateAwareObjectMapper并定义如下所示的自定义新MappingJackson2HttpMessageConverter。

首先将hibernate4的dependecy添加到pom.xml

<dependency>
            <groupId>com.fasterxml.jackson.datatype</groupId>
            <artifactId>jackson-datatype-hibernate4</artifactId>
            <version>2.5.3</version>
        </dependency>

创建HibernateAwareObjectMapper类

/**
 * https://github.com/FasterXML/jackson-datatype-hibernate
 *
 */
public class HibernateAwareObjectMapper extends ObjectMapper {

    /**
     * 
     */
    private static final long serialVersionUID = 1L;

    public HibernateAwareObjectMapper() {
        registerModule(new Hibernate4Module());
    }
}

将自定义MappingJackson2HttpMessageConverter类添加到Application.java

@Bean
    public MappingJackson2HttpMessageConverter customJackson2HttpMessageConverter() {
        MappingJackson2HttpMessageConverter jsonConverter = new MappingJackson2HttpMessageConverter();
        HibernateAwareObjectMapper hibernateAwareObjectMapper = new HibernateAwareObjectMapper();
        jsonConverter.setObjectMapper(hibernateAwareObjectMapper);
        return jsonConverter;
    }

    @Override
    public void configureMessageConverters(List<HttpMessageConverter<?>> converters) {
        converters.add(customJackson2HttpMessageConverter());
        super.addDefaultHttpMessageConverters(converters);
    }

Answer 3

感谢Evgeni提供包含答案的链接使用以下注释注释我的CompanyVO bean删除了错误 @JsonIgnoreProperties（{＆＃34; hibernateLazyInitializer＆＃34;，＆＃34; handler＆＃34;}）

Spring Rest - 生成Json数据的异常

3 个答案: