java - Jackson JSON 不包装嵌套对象的属性

Question

我有以下类(class):

public class Container {
    private String name;
    private Data data;
}

public class Data {
    private Long id;
}

当我序列化 Container我得到的使用 Jackson 的类(class)

{"name":"Some name","data":{"id":1}}

但我需要的结果是:

{"name":"Some name","id":1}

有可能吗(不添加Container.getDataId() 方法)？如果有，该怎么做？

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更新

我尝试创建自定义 JsonSerializer<Data>但结果和以前一样

public class JsonDataSerializer extends JsonSerializer<Data> {

    private static Logger logger = Logger.getLogger(JsonDataSerializer.class);

    @Override
    public void serialize(Data value, JsonGenerator jgen, 
            SerializerProvider provider)
            throws IOException,JsonProcessingException {

        Long id = (value.getId() == null) ? 0l : value.getId();
        jgen.writeStartObject();
        jgen.writeNumberField("id", id);
        jgen.writeEndObject();
        logger.debug("Data id " + id + " serialized to JSON.");       
    }
}

我也尝试添加 @JsonSerialize上面的注释Data类，然后在 Container 中高于 getter类(class)。正如我之前提到的，没有任何成功。使用了我的序列化程序，logger 记录消息。

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更新 2

当我删除 writeStartObject()和 writeEndObject()则不返回 JSON，仅返回 HTTP Status 500错误，除了我在调试输出中发现的内容之外没有抛出异常。

DEBUG: org.springframework.web.servlet.mvc.annotation.AnnotationMethodHandlerExceptionResolver - Resolving exception from handler [com.example.DataController@16be8a0]: org.springframework.http.converter.HttpMessageNotWritableException: Could not write JSON: Can not write a field name, expecting a value; nested exception is org.codehaus.jackson.JsonGenerationException: Can not write a field name, expecting a value
DEBUG: org.springframework.web.servlet.mvc.annotation.ResponseStatusExceptionResolver - Resolving exception from handler [com.example.DataController@16be8a0]: org.springframework.http.converter.HttpMessageNotWritableException: Could not write JSON: Can not write a field name, expecting a value; nested exception is org.codehaus.jackson.JsonGenerationException: Can not write a field name, expecting a value
DEBUG: org.springframework.web.servlet.mvc.support.DefaultHandlerExceptionResolver - Resolving exception from handler [com.example.DataController@16be8a0]: org.springframework.http.converter.HttpMessageNotWritableException: Could not write JSON: Can not write a field name, expecting a value; nested exception is org.codehaus.jackson.JsonGenerationException: Can not write a field name, expecting a value

Answer 1

Jackson 1.9 引入了 JsonUnwrapped注释可以满足您的需求。