Question

我正在和杰克逊一起玩多态。我有一个可行的示例，但对我来说有点奇怪。生成Json时，我得到一个重复的字段。

我有以下一棵树：花园->动物->狗或猫。

@Value
@NoArgsConstructor(force = true, access = AccessLevel.PRIVATE)
@AllArgsConstructor
public class Garden {
    public String location;
    public Animal animal;
}


@JsonIgnoreProperties(ignoreUnknown = true)
@JsonTypeInfo(use = JsonTypeInfo.Id.NAME, include = JsonTypeInfo.As.EXTERNAL_PROPERTY, property = "name", visible = true, defaultImpl = Dog.class)
@JsonSubTypes({
        @JsonSubTypes.Type(value = Dog.class, name = "Dog"),
        @JsonSubTypes.Type(value = Cat.class, name = "Cat")}
)
public interface Animal {
}

@Value
@NoArgsConstructor(force = true, access = AccessLevel.PRIVATE)
@AllArgsConstructor
public class Cat implements Animal {
    public String name;
    public String nickname;
}

@Value
@NoArgsConstructor(force = true, access = AccessLevel.PRIVATE)
@AllArgsConstructor
public class Dog implements Animal {
    public String name;
    public String command;
}

程序：

public class App {
    public static void main(String[] args) {
        ObjectMapper objectMapper = new ObjectMapper();

        Animal animal = new Dog("Dog", "Sit");
        Garden garden = new Garden("Utrecht", animal);

        try {
            String gardenJson = objectMapper.writeValueAsString(garden);

            System.out.println(gardenJson);

            Garden deserializedDog = objectMapper.readValue("{\"location\":\"Utrecht\",\"animal\":{\"name\":\"Dog\",\"command\":\"Sit\"}}", Garden.class);
            System.out.println("");
        } catch (Exception e) {
            e.printStackTrace();
        }
    }
}

当我从Json反序列化到Java时，一切都按预期运行（使用以下Json：{“ location”：“ Utrecht”，“ animal”：{“ name”：“ Dog”，“ command”：“ Sit” }}）。但是在生成Json时：

{"location":"Utrecht","animal":{"name":"Dog","name":"Dog","command":"Sit"}}

如何摆脱重复的name属性？

Answer 1

将EXTERNAL_PROPERTY替换为EXISTING_PROPERTY。所以您的示例行：

@JsonTypeInfo(use = JsonTypeInfo.Id.NAME, include = JsonTypeInfo.As.EXTERNAL_PROPERTY, property = "name", visible = true, defaultImpl = Dog.class)

需要替换为：

@JsonTypeInfo(use = JsonTypeInfo.Id.NAME, include = JsonTypeInfo.As.EXISTING_PROPERTY, property = "name", visible = true, defaultImpl = Dog.class)

Java Jackson Polymorphic-接口字段上的匹配导致字段名称重复

1 个答案: