不包括对杰克逊的空对象

Question

public class Person {
    private String name;
    private PersonDetails details;

//     getters and setters...
}

Person person = new Person();
person.setName("Apple");
person.setDetails(new PersonDetails());

因此，有一个Person的实例，其中Details为空，这正是Jackson返回的内容：

"person": {
    "name": "Apple",
    "details": {}
}

我希望json没有空括号{}:

"person": {
    "name": "Apple"
}

这个问题对我没有帮助：

null

Answer 1

如果没有自定义序列化程序，jackson将包含您的对象。

解决方案1：用null替换新对象

person.setDetails(new PersonDetails());

与

person.setDetails(null);

@JsonInclude(Include.NON_NULL)
public class Person {

public class PersonDetailsSerializer extends StdSerializer<PersonDetails> {

    public PersonDetailsSerializer() {
        this(null);
    }

    public PersonDetailsSerializer(Class<PersonDetails> t) {
        super(t);
    }

    @Override
    public void serialize(
            PersonDetails personDetails, JsonGenerator jgen, SerializerProvider provider)
            throws IOException, JsonProcessingException {
        // custom behavior if you implement equals and hashCode in your code
        if(personDetails.equals(new PersonDetails()){
           return;
        }
        super.serialize(personDetails,jgen,provider);
    }
}

public class Person {
    private String name;
    @JsonSerialize(using = PersonDetailsSerializer.class)
    private PersonDetails details;
}