无字段名的Jackson JSON序列化

Question

{
  "isA" : "Human",
  "name" : "Batman",
  "age" : "2008",
  "others" : {
    "key1" : "value1",
    "key2" : {
      "key3" : "value3"
    },
    "key5" : {
      "key4" : "One",
      "key4" : "Two"
    }
  }
}

我希望获得以下输出：（我所要做的就是删除map 字段名，但保留其子字段名。）

{
  "isA" : "Human",
  "name" : "Batman",
  "age" : "2008",
  "key1" : "value1",
  "key2" : {
    "key3" : "value3"
  },
  "key5" : {
    "key4" : "One",
    "key4" : "Two"
  }
}

以下是我的human.classPOJO，由ObjectMapper使用：

@JsonTypeInfo(use = JsonTypeInfo.Id.NAME, include = JsonTypeInfo.As.PROPERTY, visible = true, property = "isA")
@JsonInclude(JsonInclude.Include.NON_NULL)
@JsonIgnoreProperties(ignoreUnknown = true)
@Getter
@Setter
@NoArgsConstructor
@ToString
class Human {
    private String isA;
    private String name;
    private String age;

    @JsonSerialize(using = MyCustomSearlize.class)
    private Map<String, Object> others = new HashMap<>();
}

下面是MAP在搜索过程中使用的我的自定义搜索器:

class MyCustomSearlize extends JsonSerializer<Map<String, Object>> {

    private static final ObjectMapper mapper = new ObjectMapper();

    @Override
    public void serialize(Map<String, Object> value, JsonGenerator gen, SerializerProvider serializers) throws IOException {
        gen.writeStartObject();
        recusiveSerializer(value, gen, serializers);
        gen.writeEndObject();
    }

    public void recusiveSerializer(Map<String, Object> value, JsonGenerator gen, SerializerProvider serializers) throws IOException {
        for (Map.Entry<String, Object> extension : value.entrySet()) {
            if (extension.getValue() instanceof Map) {
                //If instance is MAP then call the recursive method
                gen.writeFieldName(extension.getKey());
                gen.writeStartObject();
                recusiveSerializer((Map) extension.getValue(), gen, serializers);
                gen.writeEndObject();
            } else if (extension.getValue() instanceof String) {
                //If instance is String directly add it to the JSON
                gen.writeStringField(extension.getKey(), (String) extension.getValue());
            } else if (extension.getValue() instanceof ArrayList) {
                //If instance if ArrayList then loop over it and add it to the JSON after calling recursive method
                for (Object dupItems : (ArrayList<Object>) extension.getValue()) {
                    if (dupItems instanceof Map) {
                        gen.writeFieldName(extension.getKey());
                        gen.writeStartObject();
                        recusiveSerializer((Map) dupItems, gen, serializers);
                        gen.writeEndObject();
                    } else {
                        gen.writeStringField(extension.getKey(), (String) dupItems);
                    }
                }
            }
        }
    }
}

public class Main {
    public static void main(String[] args) throws JsonProcessingException {

        Human person = new Human();

        person.setName("Batman");
        person.setAge("2008");
        Map<String, Object> others = new HashMap<>();
        others.put("key1", "value1");
        Map<String, Object> complex = new HashMap<>();
        complex.put("key3", "value3");
        others.put("key2", complex);
        Map<String, Object> complex2 = new HashMap<>();
        List<String> dup = new ArrayList<>();
        dup.add("One");
        dup.add("Two");
        complex2.put("key4", dup);
        others.put("key5", complex2);
        person.setOthers(others);

        final ObjectMapper objectMapper = new ObjectMapper();
        SimpleModule simpleModule = new SimpleModule();
        objectMapper.registerModule(simpleModule);
        final String jsonEvent = objectMapper.writerWithDefaultPrettyPrinter().writeValueAsString(person);
        System.out.println(jsonEvent);
    }
}

null

是否有一种方法可以使它与@jsonSerialize和@jsonanygetter一起使用，因为我不能同时使用这两种方法。

有人能帮忙解决这个问题吗？请指导我适当的文档或变通方法，非常感谢。

Answer 1

从wiki页面上看，@jsonunwrapped注释应该做您想做的事情。

@jsonunwrapped:property注释用于定义该值在序列化时应该“解包装”（反序列化时再次包装），与POJO结构相比，导致数据结构扁平化。

类的Javadoc也有一个看起来合适的示例。