JSON杰克逊注释被忽略了

Question

I am using @JsonIgnore and still getting StackoverflowError.

There's a cycle and the annotation is ignored.

@Entity
@NamedQuery(name="Buch.findAll", query="SELECT b FROM Buch v")
public class Buch implements Serializable {
    private static final long serialVersionUID = 1L;

    ...

    //bi-directional many-to-one association to Titel
    @OneToOne(mappedBy="buch")
    @JsonIgnore
    private Titel Titel;

    ...

    @JsonIgnore
    public Titel getTitel() {
        return this.verein;
    }

    @JsonIgnore
    public void setTitel(Titel titel) {
        this.titel= titel;
    }
}

Answer 1

Well there are several problems in your code:

• You are using @JsonIgnore annotation with both field and its accessors(getter and setter), you should't do that, mapping only one of them is sufficient. I suggest you map only the getter method with @JsonIgnore .
• Another thing is that your Titel 's getter method is not correctly implemented, it should return Titel field but you are returning this.verein , this is totally wrong and will mess up the logic of your code, you need to correct it.

What I suggest here is to use @JsonIgnore only with the getter method which you need to correct:

@JsonIgnore
public Titel getTitel() {
    return this.Titel;
}

Answer 2

I think that this code will not work the title will not set by (jackson ex) because you're making a @JsonIgnore on a setter change it with @JsonSetter and on your getters add @JsonIgnore :

@JsonIgnore
public Titel getTitel() {
    return this.verein;
}

@JsonSetter
public void setTitel(Titel titel) {
    this.titel= titel;
}