杰克逊注解不与 Spring Boot 一起使用

【问题标题】：Jackson annotations not used with Spring boot杰克逊注解不与 Spring Boot 一起使用
【发布时间】：2014-05-28 03:49:53
【问题描述】：

我正在使用 Spring boot 1.0.1.RELEASE 并试图让它获取一些 Jackson 注释。更具体地说，我正在尝试使用 @JsonManagedReference 和 @JsonBackReference 注释。知道为什么这可能会被忽略吗？我也尝试了@JsonIgnore，但似乎也没有被采纳。

我已经尝试了in this SO question 中提到的两件事（将 Jackson 注释移到第一位并使用 List 而不是 Set）。我还查看了this question on the Spring forums，但这也对我没有帮助。

更新：

这是我的ComponentType 班级：

@Entity
public class ComponentType
{
// ------------------------------ FIELDS ------------------------------

    @Id
    @GeneratedValue()
    private long m_id;

    private String m_name;

    @JsonManagedReference
    @OneToMany(cascade = CascadeType.ALL)
    @JoinColumn(name = "parent_id")
    private List<ComponentSubtype> m_subtypes;

// --------------------------- CONSTRUCTORS ---------------------------

    public ComponentType()
    {
    }

    public ComponentType( String name, Iterable<ComponentSubtype> subtypes )
    {
        m_name = name;
        m_subtypes = Lists.newArrayList(subtypes);
    }

    // -------------------------- PUBLIC METHODS --------------------------

    public long getId()
    {
        return m_id;
    }

    public void setId( long id )
    {
        m_id = id;
    }

    public String getName()
    {
        return m_name;
    }

    public void setName( String name )
    {
        m_name = name;
    }

    public List<ComponentSubtype> getSubtypes()
    {
        return m_subtypes;
    }

    public void setSubtypes( List<ComponentSubtype> subtypes )
    {
        m_subtypes = subtypes;
    }

    public ComponentSubtype getSubtype( final long subtypeId )
    {
        return Iterables.find( getSubtypes(), new Predicate<ComponentSubtype>()
        {
            @Override
            public boolean apply( ComponentSubtype input )
            {
                return input.getId() == subtypeId;
            }
        } );
    }

这是ComponentSubtype：

@Entity
public class ComponentSubtype
{
    @Id
    @GeneratedValue()
    private long m_id;

    private String m_name;

    @JsonBackReference
    @ManyToOne(fetch = FetchType.LAZY)
    @JoinColumn(name = "parent_id",insertable=false,updatable=false)
    private ComponentType m_componentType;

    public ComponentSubtype()
    {
    }

    public ComponentSubtype( String name )
    {
        m_name = name;
    }

    public long getId()
    {
        return m_id;
    }

    public void setId( long id )
    {
        m_id = id;
    }

    public String getName()
    {
        return m_name;
    }

    public void setName( String name )
    {
        m_name = name;
    }

    public ComponentType getComponentType()
    {
        return m_componentType;
    }

    public void setComponentType( ComponentType componentType )
    {
        m_componentType = componentType;
    }
}

控制器：

@RestController
@RequestMapping("/api/components")
public class ComponentTypeController
{
    @Autowired
    private ComponentTypeRepository m_repository;

    @RequestMapping("/list")
    public Iterable<ComponentType> listComponents()
    {
        return m_repository.findAll();
    }
}

还有存储库：

public interface ComponentTypeRepository extends CrudRepository<ComponentType, Long>
{
}

我主要创建了一些用于测试的实体：

    ConfigurableApplicationContext context = SpringApplication.run( Main.class, args );
ComponentTypeRepository componentTypeRepository = context.getBean( ComponentTypeRepository.class );
componentTypeRepository.save( new ComponentType( "Component A", Sets.newHashSet( new ComponentSubtype( "Sub A - 1" ), new ComponentSubtype( "Sub A - 2" ) ) ) );
componentTypeRepository.save( new ComponentType( "Component B", Sets.newHashSet( new ComponentSubtype( "Sub B - 1" ), new ComponentSubtype( "Sub B - 2" ) ) ) );
componentTypeRepository.save( new ComponentType( "Component C", Sets.newHashSet( new ComponentSubtype( "Sub C - 1" ), new ComponentSubtype( "Sub C - 2" ) ) ) );
componentTypeRepository.save( new ComponentType( "Component D", Sets.newHashSet( new ComponentSubtype( "Sub D - 1" ),
                                                                                 new ComponentSubtype( "Sub D - 2" ),
                                                                                 new ComponentSubtype( "Sub D - 3" )
) ) );

如果我将浏览器指向http://localhost:8080/api/components/list，则会收到 stackoverflow 异常。

这是我得到的堆栈跟踪的一部分：

java.lang.StackOverflowError: null
    at java.lang.ClassLoader.defineClass1(Native Method)
    at java.lang.ClassLoader.defineClass(ClassLoader.java:800)
    at java.security.SecureClassLoader.defineClass(SecureClassLoader.java:142)
    at java.net.URLClassLoader.defineClass(URLClassLoader.java:449)
    at java.net.URLClassLoader.access$100(URLClassLoader.java:71)
    at java.net.URLClassLoader$1.run(URLClassLoader.java:361)
    at java.net.URLClassLoader$1.run(URLClassLoader.java:355)
    at java.security.AccessController.doPrivileged(Native Method)
    at java.net.URLClassLoader.findClass(URLClassLoader.java:354)
    at java.lang.ClassLoader.loadClass(ClassLoader.java:425)
    at sun.misc.Launcher$AppClassLoader.loadClass(Launcher.java:308)
    at java.lang.ClassLoader.loadClass(ClassLoader.java:358)
    at com.fasterxml.jackson.databind.ser.std.BeanSerializerBase.serializeFields(BeanSerializerBase.java:660)
    at com.fasterxml.jackson.databind.ser.BeanSerializer.serialize(BeanSerializer.java:152)
    at com.fasterxml.jackson.databind.ser.BeanPropertyWriter.serializeAsField(BeanPropertyWriter.java:541)
    at com.fasterxml.jackson.databind.ser.std.BeanSerializerBase.serializeFields(BeanSerializerBase.java:644)
    at com.fasterxml.jackson.databind.ser.BeanSerializer.serialize(BeanSerializer.java:152)
    at com.fasterxml.jackson.databind.ser.std.CollectionSerializer.serializeContents(CollectionSerializer.java:117)
    at com.fasterxml.jackson.databind.ser.std.CollectionSerializer.serializeContents(CollectionSerializer.java:23)
    at com.fasterxml.jackson.databind.ser.std.AsArraySerializerBase.serialize(AsArraySerializerBase.java:183)
    at com.fasterxml.jackson.databind.ser.BeanPropertyWriter.serializeAsField(BeanPropertyWriter.java:541)
    at com.fasterxml.jackson.databind.ser.std.BeanSerializerBase.serializeFields(BeanSerializerBase.java:644)
    at com.fasterxml.jackson.databind.ser.BeanSerializer.serialize(BeanSerializer.java:152)
    at com.fasterxml.jackson.databind.ser.BeanPropertyWriter.serializeAsField(BeanPropertyWriter.java:541)
    at com.fasterxml.jackson.databind.ser.std.BeanSerializerBase.serializeFields(BeanSerializerBase.java:644)
    at com.fasterxml.jackson.databind.ser.BeanSerializer.serialize(BeanSerializer.java:152)
    at com.fasterxml.jackson.databind.ser.std.CollectionSerializer.serializeContents(CollectionSerializer.java:117)
    at com.fasterxml.jackson.databind.ser.std.CollectionSerializer.serializeContents(CollectionSerializer.java:23)
    at com.fasterxml.jackson.databind.ser.std.AsArraySerializerBase.serialize(AsArraySerializerBase.java:183)
    at com.fasterxml.jackson.databind.ser.BeanPropertyWriter.serializeAsField(BeanPropertyWriter.java:541)
    at com.fasterxml.jackson.databind.ser.std.BeanSerializerBase.serializeFields(BeanSerializerBase.java:644)
    at com.fasterxml.jackson.databind.ser.BeanSerializer.serialize(BeanSerializer.java:152)
    at com.fasterxml.jackson.databind.ser.BeanPropertyWriter.serializeAsField(BeanPropertyWriter.java:541)
    at com.fasterxml.jackson.databind.ser.std.BeanSerializerBase.serializeFields(BeanSerializerBase.java:644)
    at com.fasterxml.jackson.databind.ser.BeanSerializer.serialize(BeanSerializer.java:152)
    at com.fasterxml.jackson.databind.ser.std.CollectionSerializer.serializeContents(CollectionSerializer.java:117)
    at com.fasterxml.jackson.databind.ser.std.CollectionSerializer.serializeContents(CollectionSerializer.java:23)
    at com.fasterxml.jackson.databind.ser.std.AsArraySerializerBase.serialize(AsArraySerializerBase.java:183)
    at com.fasterxml.jackson.databind.ser.BeanPropertyWriter.serializeAsField(BeanPropertyWriter.java:541)
    at com.fasterxml.jackson.databind.ser.std.BeanSerializerBase.serializeFields(BeanSerializerBase.java:644)
    at com.fasterxml.jackson.databind.ser.BeanSerializer.serialize(BeanSerializer.java:152)
    at com.fasterxml.jackson.databind.ser.BeanPropertyWriter.serializeAsField(BeanPropertyWriter.java:541)
    at com.fasterxml.jackson.databind.ser.std.BeanSerializerBase.serializeFields(BeanSerializerBase.java:644)
    at com.fasterxml.jackson.databind.ser.BeanSerializer.serialize(BeanSerializer.java:152)
    at com.fasterxml.jackson.databind.ser.std.CollectionSerializer.serializeContents(CollectionSerializer.java:117)
    at com.fasterxml.jackson.databind.ser.std.CollectionSerializer.serializeContents(CollectionSerializer.java:23)
    at com.fasterxml.jackson.databind.ser.std.AsArraySerializerBase.serialize(AsArraySerializerBase.java:183)
    at com.fasterxml.jackson.databind.ser.BeanPropertyWriter.serializeAsField(BeanPropertyWriter.java:541)
    at com.fasterxml.jackson.databind.ser.std.BeanSerializerBase.serializeFields(BeanSerializerBase.java:644)
    at com.fasterxml.jackson.databind.ser.BeanSerializer.serialize(BeanSerializer.java:152)
    at com.fasterxml.jackson.databind.ser.BeanPropertyWriter.serializeAsField(BeanPropertyWriter.java:541)
    at com.fasterxml.jackson.databind.ser.std.BeanSerializerBase.serializeFields(BeanSerializerBase.java:644)
    at com.fasterxml.jackson.databind.ser.BeanSerializer.serialize(BeanSerializer.java:152)
    at com.fasterxml.jackson.databind.ser.std.CollectionSerializer.serializeContents(CollectionSerializer.java:117)
    at com.fasterxml.jackson.databind.ser.std.CollectionSerializer.serializeContents(CollectionSerializer.java:23)
    at com.fasterxml.jackson.databind.ser.std.AsArraySerializerBase.serialize(AsArraySerializerBase.java:183)
    at com.fasterxml.jackson.databind.ser.BeanPropertyWriter.serializeAsField(BeanPropertyWriter.java:541)
    at com.fasterxml.jackson.databind.ser.std.BeanSerializerBase.serializeFields(BeanSerializerBase.java:644)
    at com.fasterxml.jackson.databind.ser.BeanSerializer.serialize(BeanSerializer.java:152)
    at com.fasterxml.jackson.databind.ser.BeanPropertyWriter.serializeAsField(BeanPropertyWriter.java:541)
    at com.fasterxml.jackson.databind.ser.std.BeanSerializerBase.serializeFields(BeanSerializerBase.java:644)
    at com.fasterxml.jackson.databind.ser.BeanSerializer.serialize(BeanSerializer.java:152)
    at com.fasterxml.jackson.databind.ser.std.CollectionSerializer.serializeContents(CollectionSerializer.java:117)
    at com.fasterxml.jackson.databind.ser.std.CollectionSerializer.serializeContents(CollectionSerializer.java:23)
    at com.fasterxml.jackson.databind.ser.std.AsArraySerializerBase.serialize(AsArraySerializerBase.java:183)
    at com.fasterxml.jackson.databind.ser.BeanPropertyWriter.serializeAsField(BeanPropertyWriter.java:541)
    at com.fasterxml.jackson.databind.ser.std.BeanSerializerBase.serializeFields(BeanSerializerBase.java:644)
    at com.fasterxml.jackson.databind.ser.BeanSerializer.serialize(BeanSerializer.java:152)
    at com.fasterxml.jackson.databind.ser.BeanPropertyWriter.serializeAsField(BeanPropertyWriter.java:541)
    at com.fasterxml.jackson.databind.ser.std.BeanSerializerBase.serializeFields(BeanSerializerBase.java:644)
    at com.fasterxml.jackson.databind.ser.BeanSerializer.serialize(BeanSerializer.java:152)
    at com.fasterxml.jackson.databind.ser.std.CollectionSerializer.serializeContents(CollectionSerializer.java:117)
    at com.fasterxml.jackson.databind.ser.std.CollectionSerializer.serializeContents(CollectionSerializer.java:23)
    at com.fasterxml.jackson.databind.ser.std.AsArraySerializerBase.serialize(AsArraySerializerBase.java:183)
    at com.fasterxml.jackson.databind.ser.BeanPropertyWriter.serializeAsField(BeanPropertyWriter.java:541)
    at com.fasterxml.jackson.databind.ser.std.BeanSerializerBase.serializeFields(BeanSerializerBase.java:644)
    at com.fasterxml.jackson.databind.ser.BeanSerializer.serialize(BeanSerializer.java:152)
    at com.fasterxml.jackson.databind.ser.BeanPropertyWriter.serializeAsField(BeanPropertyWriter.java:541)
    at com.fasterxml.jackson.databind.ser.std.BeanSerializerBase.serializeFields(BeanSerializerBase.java:644)
    at com.fasterxml.jackson.databind.ser.BeanSerializer.serialize(BeanSerializer.java:152)
    at com.fasterxml.jackson.databind.ser.std.CollectionSerializer.serializeContents(CollectionSerializer.java:117)
    at com.fasterxml.jackson.databind.ser.std.CollectionSerializer.serializeContents(CollectionSerializer.java:23)
    at com.fasterxml.jackson.databind.ser.std.AsArraySerializerBase.serialize(AsArraySerializerBase.java:183)
    at com.fasterxml.jackson.databind.ser.BeanPropertyWriter.serializeAsField(BeanPropertyWriter.java:541)
    at com.fasterxml.jackson.databind.ser.std.BeanSerializerBase.serializeFields(BeanSerializerBase.java:644)
    at com.fasterxml.jackson.databind.ser.BeanSerializer.serialize(BeanSerializer.java:152)
    at com.fasterxml.jackson.databind.ser.BeanPropertyWriter.serializeAsField(BeanPropertyWriter.java:541)
    at com.fasterxml.jackson.databind.ser.std.BeanSerializerBase.serializeFields(BeanSerializerBase.java:644)
    at com.fasterxml.jackson.databind.ser.BeanSerializer.serialize(BeanSerializer.java:152)
    at com.fasterxml.jackson.databind.ser.std.CollectionSerializer.serializeContents(CollectionSerializer.java:117)
    at com.fasterxml.jackson.databind.ser.std.CollectionSerializer.serializeContents(CollectionSerializer.java:23)
    at com.fasterxml.jackson.databind.ser.std.AsArraySerializerBase.serialize(AsArraySerializerBase.java:183)
    at com.fasterxml.jackson.databind.ser.BeanPropertyWriter.serializeAsField(BeanPropertyWriter.java:541)
    at com.fasterxml.jackson.databind.ser.std.BeanSerializerBase.serializeFields(BeanSerializerBase.java:644)
    at com.fasterxml.jackson.databind.ser.BeanSerializer.serialize(BeanSerializer.java:152)
    at com.fasterxml.jackson.databind.ser.BeanPropertyWriter.serializeAsField(BeanPropertyWriter.java:541)
    at com.fasterxml.jackson.databind.ser.std.BeanSerializerBase.serializeFields(BeanSerializerBase.java:644)
    at com.fasterxml.jackson.databind.ser.BeanSerializer.serialize(BeanSerializer.java:152)
    at com.fasterxml.jackson.databind.ser.std.CollectionSerializer.serializeContents(CollectionSerializer.java:117)
    at com.fasterxml.jackson.databind.ser.std.CollectionSerializer.serializeContents(CollectionSerializer.java:23)
    at com.fasterxml.jackson.databind.ser.std.AsArraySerializerBase.serialize(AsArraySerializerBase.java:183)
    at com.fasterxml.jackson.databind.ser.BeanPropertyWriter.serializeAsField(BeanPropertyWriter.java:541)
    at com.fasterxml.jackson.databind.ser.std.BeanSerializerBase.serializeFields(BeanSerializerBase.java:644)
    at com.fasterxml.jackson.databind.ser.BeanSerializer.serialize(BeanSerializer.java:152)
    at com.fasterxml.jackson.databind.ser.BeanPropertyWriter.serializeAsField(BeanPropertyWriter.java:541)
    at com.fasterxml.jackson.databind.ser.std.BeanSerializerBase.serializeFields(BeanSerializerBase.java:644)
    at com.fasterxml.jackson.databind.ser.BeanSerializer.serialize(BeanSerializer.java:152)
    at com.fasterxml.jackson.databind.ser.std.CollectionSerializer.serializeContents(CollectionSerializer.java:117)
    at com.fasterxml.jackson.databind.ser.std.CollectionSerializer.serializeContents(CollectionSerializer.java:23)

演示问题的示例项目：

从https://dl.dropboxusercontent.com/u/6373261/jackson-problem.zip下载

【问题讨论】：

  • 您使用的是什么版本的 Jackson？确保它是 Spring Boot 支持的（例如，通过使用 starter pom 作为依赖项 - Jackson 包含在 web starter 中）。
  • 我正在使用 spring-boot-starter-web 依赖，这似乎给了我 Jackson 2.3.2
  • 好的，那么它应该可以工作了。你想更准确地做什么？也许在问题中添加一些代码？
  • 我已经添加了我的代码。谢谢你看。有什么方法可以让 Jackson 进行更多调试？
  • 谢谢，这有帮助。那么你的端点会产生什么？如果是 JSON，我猜 Jackson 正在工作，但您的字段级注释不是？ Mayeb，您也可以将异常中的一小部分循环放在问题中吗？

标签： java spring jackson spring-boot


【解决方案1】：

这是字段（“m_*”）的（老式 IMO）命名约定。 Jackson 没有将它们与 getter 和 setter 关联起来。所以你必须要么@JsonIgnore getter 和 setter，要么改变你的命名，要么注释 getter。或者@JsonBackReference(...) 中可能有一个功能？例如，@JsonBackReference("componentType") 可能会起作用。

【讨论】：

  • 我最终将注释从字段移动到 getter 以修复它。
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