使用Jackson：在json字符串中获取重复的字段

Question

I have a POJO with Jackson annotations:

public class Person {
    @JsonProperty("first_name")
    private String firstName;

    @JsonProperty("last_name")
    private String lastName;

    public String getFirstName() {
        return this.firstName;
    }

    public void setFirstName(String firstName) {
        this.firstName = firstName;
    }

    public String getLastName() {
        return this.lastName;
    }

    public void setLastName(String lastName) {
        this.lastName = lastName;
    }

}

Then I created a Person instance & parse it to json string:

Person p = new Person();
p.setFirstName("John");
p.setLastName("Smith");

//parse to json string
ObjectMapper mapper = new ObjectMapper();
String personJson = mapper.writeValueAsString(p);

But the json string ( personJson ) I got is the following:

{"first_name":"John","last_name":"Smith","firstName":"John","lastName":"Smith"}

Why I get duplicated fields " first_name " & " firstName ", so to " last_name " & " lastName " in JSON string?

===== UPDATE ===

I also tried :

Annotation:

@JsonAutoDetect(fieldVisibility = JsonAutoDetect.Visibility.ANY, getterVisibility = JsonAutoDetect.Visibility.NONE,
        setterVisibility = JsonAutoDetect.Visibility.NONE, creatorVisibility = JsonAutoDetect.Visibility.NONE,
        isGetterVisibility = JsonAutoDetect.Visibility.NONE)

ObjectMapper:

ObjectMapper mapper = new ObjectMapper();
    mapper.getSerializationConfig().getDefaultVisibilityChecker()
            .withFieldVisibility(JsonAutoDetect.Visibility.ANY)
            .withGetterVisibility(JsonAutoDetect.Visibility.NONE)
            .withSetterVisibility(JsonAutoDetect.Visibility.NONE)
            .withCreatorVisibility(JsonAutoDetect.Visibility.NONE);

But I still get the duplicated attributes in JSON in some other POJO...

Answer 1

I managed to solve the problem myself.

The reason why I still got duplicated fields in JSON after the UPDATE is that there are boolean properties in my other POJO which yields the accessor methods starting with " is " , eg:

public class Other {
   @JsonProperty("money_paid")
   private boolean moneyPaid;

   public boolean isMoneyPaid() {
    return moneyPaid;
   } 
   ... 
}

So, the generated json contained {money_paid:true, moneyPaid:true}. To get rid of it, I just added one more restriction on mapper when setVisibilityChecker , which is:

.withIsGetterVisibility(JsonAutoDetect.Visibility.NONE)