无法写入HTTP消息：org.SpringFramework.HTTP.Converter.HttpMessageNotWritableException：

Question

我是Spring MVC框架的新手。我试图在我的Spring项目中使用Hibernate返回object来检索用户详细信息。我得到以下错误：

警告：org.springframework.web.servlet.mvc.support.defaultHandlerExceptionResolver-无法写入HTTP消息：org.springframework.HTTP.converter.httpmessagenotwritableException：无法写入内容：未找到类org.hibernate.proxy.pojo.javassist.javassistlazyInitializer的序列化程序，也未发现创建BeanSerializer的属性（为避免出现异常，请禁用SerializationFeature.fail_on_empty_beans))（通过引用链s.mschef.model.user_$$_JVSTB3_6[“处理程序”])

有人能告诉这个错误的解决方法吗？？

Answer 1

This works for me : 
http://www.geekabyte.io/2013/09/fixing-converterhttpmessagenotwritablee.html


The fix is to get Jackson to be able to handle bi-directional references. And this is done by using two Annotations: @JsonManagedReference and @JsonBackReference.

@JsonManagedReference is used to annotate the inverse side while @JsonBackReference maps the owning side of the relationship.

Example :
@Entity
class Parent {

     @Id
     @Column(name="parent_id")
     @GeneratedValue(strategy = GenerationType.AUTO)
     private Long id;

     private String name;
     private Parent wife;

     @OneToMany(mappedBy="parent" cascade = CascadeType.ALL)
     @JsonManagedReference
     private Collection<Child> children = new ArrayList<>();
...
}


@Entity
class Child {
    private String name;

    @ManyToOne
    @JoinColumn(name="parent_id", referencedColumn="parent_id")
    @JsonBackReference
    private Parent parent;
...
}