Spring REST：HttpMediaTypeNotSupportedException：内容类型'application / json; charset = UTF-8'

Question

I am getting the above error, due to a problem with Jackson attempting to deserialize my POJO.

I've debugged the code and it returns false within Jackson's ObjectMapper:

public boolean canRead(Type type, Class<?> contextClass, MediaType mediaType) {
    JavaType javaType = getJavaType(type, contextClass);
    return (this.objectMapper.canDeserialize(javaType) && canRead(mediaType));
}

this.objectMapper.canDeserialize(javaType) returns false which causes the error

My Controller is as follows:

@Controller
public class CancelController {
    @Autowired
    private CancelService cancelService;

    @RequestMapping( value="/thing/cancel", method=RequestMethod.POST, consumes="application/json" )
    public @ResponseBody CancelThingResponseDTO cancelThing(@RequestBody CancelRequestDTO cancelThingRequest) {
        return cancelService.cancelThing(cancelThingRequest);
    }

My CancelRequestDTO implements Serializable:

public class CancelRequestDTO implements Serializable{
  /**
   * Default serialization ID
   */
  private static final long serialVersionUID = 1L;
  /**
   * Reason code associated with the request
   */
  private final String reasonCode;
  /**
   * Identifier of the entity associated with the request
   */
  private final EntityIdentifier entityIdentifier;

  /**
   * Default constructor
   *
   * @param reasonCode Reason code associated with the request
   * @param entityIdentifier Identifier of the entity associated with the request
   */
  public CancelRequestDTO(String reasonCode, EntityIdentifier entityIdentifier) {
    super();
    this.reasonCode = reasonCode;
    this.entityIdentifier = entityIdentifier;
  }
  /**
   * @return Returns the reasonCode.
   */
  public String getReasonCode() {
    return reasonCode;
  }
  /**
   * @return Returns the entityIdentifier.
   */
  public EntityIdentifier getEntityIdentifier() {
    return entityIdentifier;
  }
}

My Spring configuration is as follow:

<!-- DispatcherServlet Context: defines this servlet's request-processing
    infrastructure -->

<!-- Enables the Spring MVC @Controller programming model -->
<mvc:annotation-driven />

<!-- Scan for stereotype annotations -->
<context:component-scan base-package="com.cancel.web.controller" />

<bean id="viewNameTranslator"
    class="org.springframework.web.servlet.view.DefaultRequestToViewNameTranslator" />

<bean class="org.springframework.web.servlet.view.BeanNameViewResolver" />





<bean id="jsonView"
    class="org.springframework.web.servlet.view.json.MappingJacksonJsonView" >
    <property name="contentType" value="application/json;charset=UTF-8"/>
    </bean>

<!-- Register JSON Converter for RESTful Web Service -->
<bean
    class="org.springframework.web.servlet.mvc.annotation.AnnotationMethodHandlerAdapter">
    <property name="messageConverters">
        <list>
            <bean
                class="org.springframework.http.converter.json.MappingJacksonHttpMessageConverter">
            </bean>
        </list>
    </property>
</bean>

Anyone know what might be causing this deserialization issue?

Thanks

Answer 1

Caused by my DTO not having a default constructor with setters! So looks like an inaccurate Exception from Jackson

Answer 2

对于仍然面临这个问题的人，你不能在一个类中有两个@JsonBackReference ，像这样添加一个引用@JsonBackReference(value = "secondParent")也将相同的值添加到@JsonManagedReference(value ="secondParent")在父类中。

Answer 3

I have always done this using the ContentNegotiatingViewResolver. It seems that it is not understanding the content type that you are passing it. This is the configuration that I typically use for doing what you are trying to do:

<bean class="org.springframework.web.servlet.view.ContentNegotiatingViewResolver">
    <property name="order" value="1" />
    <property name="contentNegotiationManager">
        <bean class="org.springframework.web.accept.ContentNegotiationManager">
            <constructor-arg>
                <bean class="org.springframework.web.accept.PathExtensionContentNegotiationStrategy">
                    <constructor-arg>
                        <map>
                            <entry key="json" value="application/json" />
                            <entry key="xml" value="application/xml" />
                        </map>
                    </constructor-arg>
                </bean>
            </constructor-arg>
        </bean>
    </property>

    <property name="defaultViews">
        <list>
            <bean class="org.springframework.web.servlet.view.json.MappingJacksonJsonView" />
            <bean class="org.springframework.web.servlet.view.xml.MarshallingView">
                <constructor-arg>
                    <bean class="org.springframework.oxm.xstream.XStreamMarshaller">
                        <property name="autodetectAnnotations" value="true" />
                    </bean>
                </constructor-arg>
            </bean>
        </list>
    </property>
</bean>

This video goes through doing exactly what you are trying to do with consuming the service through jQuery in the UI:

http://pluralsight.com/training/Courses/TableOfContents/springmvc-intro