与Jackson重复的JSON字段 [英] Duplicate JSON Field with Jackson

问题描述

我正在与Spring结合使用Jackson进行JSON(反)序列化.但是，在某些情况下，我遇到了一个字段为两次的问题.

I am using Jackson for JSON (de)serialization in conjunction with Spring. However I am having an issue with a field being twice in some cases.

我有一个抽象类:

@JsonTypeInfo(use = JsonTypeInfo.Id.NAME, include = JsonTypeInfo.As.PROPERTY, property = "mimeType")
@JsonSubTypes({
    @JsonSubTypes.Type(value = ImageBookmarkJsonModel.class, name = "image/jpeg"),
    @JsonSubTypes.Type(value = EpubBookmarkJsonModel.class, name = "application/epub+zip")
})
public abstract class AbstractBookmarkJsonModel extends AbstractJsonModel {
    protected String mimeType;
    // Removed other fields for brevity

    public String getMimeType() {
        return mimeType;
    }

    public void setMimeType(String mimeType) {
        this.mimeType = mimeType;
    }

    @Override
    public String toString() {
        ObjectMapper mapper = new ObjectMapper();

        try {
            return mapper.writeValueAsString(this);
        } catch (IOException e) {
            throw new IllegalStateException("Cannot convert object of type " + this.getClass().toString() + " to JSON", e);
        }
    }
}

一个具体的类扩展了抽象:

And a concrete class extend the abstract:

public class EpubBookmarkJsonModel extends AbstractBookmarkJsonModel {
    private static final long serialVersionUID = 1L;
    // Removed other fields for brevity

    public EpubBookmarkJsonModel() {
        this.mimeType = "application/epub+zip";
    }
}

问题是，当我序列化此JSON时，我得到一个重复的mimeType字段:

The problem is that when I serialize this JSON, I get a duplicate mimeType field:

{
  "mimeType": "application/epub+zip",
  "mimeType": "application/epub+zip",
  "userId": 24,
  "acid": "ACID-000000000029087",
  "added": "2013-08-14T12:02:17Z",
  "epubBookmarkId": 34,
  "cfi": "epubcfi(/6/4!/2/68)",
  "context": "CONTEXT"
}

我尝试使用答案使用@JsonAutoDetect批注指定仅使用类上的字段以及在ObjectMapper上设置相同的字段，但这不能解决问题.

I have tried using the recommendation of previous answers to use the @JsonAutoDetect annotation to specify that only fields on a class should be used as well as setting the same on the ObjectMapper, however this does not fix the problem.

注释:

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

ObjectMapper:

ObjectMapper:

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

推荐答案

我通过使用@JsonTypeInfo批注中的JsonTypeInfo.As.EXISTING_PROPERTY解决了这个问题.

I solved this by using the JsonTypeInfo.As.EXISTING_PROPERTY in the @JsonTypeInfo annotation.

该项目是开源的，请在此处查看:ANS.java

The project is open source, check it out here: ANS.java

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