java - Jackson-反序列化嵌套的JSON

我有一个JSON字符串，其格式如下:

{
  "response": {
    "execution_status": "ready",
    "report": {
      "cache_hit": true,
      "created_on": "2013-07-29 08:42:42",
      "fact_cache_error": null,
      "fact_cache_hit": true,
      "header_info": null,
      "name": null,
      "report_size": "5871",
      "row_count": "33",
      "url": "report-download?id=278641c223bc4e4d63df9e83d8fcb4e6"
     },
  "status": "OK"
  }
}

JSON的响应部分对于一堆响应类型很常见。 JSON的报告部分仅对此响应有用。因此，我创建了一个如下所示的Response类，其中包含getter和setter(为简洁起见，此处未包括getter和setter):

@JsonRootName(value = "response")
public class Response implements Serializable {

    private static final long serialVersionUID = -2597493920293381637L;

    @JsonProperty(value = "error")
    private String error;
    @JsonProperty(value = "error_code")
    private String errorCode;
    @JsonProperty(value = "error_id")
    private String errorId;
    @JsonProperty(value = "error_description")
    private String errorDescription;
    @JsonProperty(value = "method")
    private String method;
    @JsonProperty(value = "service")
    private String service;
    @JsonProperty(value = "status")
    private String status;
    @JsonProperty(value = "execution_status")
    private String executionStatus;
}

然后，我创建了一个Report类，其中带有report元素中的字段，如下所示。 ReportResponse类将从Response类扩展(同样，为简洁起见，不包括getter和setter):

public class ReportResponse extends Response {

    private static final long serialVersionUID = 4950819240030644407L;

    @JsonProperty(value = "cache_hit")
    private Boolean cacheHit;
    @JsonProperty(value = "created_on")
    private Timestamp createdOn;
    @JsonProperty(value = "fact_cache_error")
    private String factCacheError;
    @JsonProperty(value = "fact_cache_hit")
    private Boolean factCacheHit;
    @JsonProperty(value = "header_info")
    private String headerInfo;
    @JsonProperty(value = "json_request")
    private String jsonRequest;
    @JsonProperty(value = "name")
    private String name;
    @JsonProperty(value = "report_size")
    private Integer reportSize;
    @JsonProperty(value = "row_count")
    private Integer rowCount;
    @JsonProperty(value = "url")
    private String url;
}

现在，当我使用ObjectMapper映射到ReportResponse对象时，出现以下错误:

String jsonString = "{\"response\": {\"execution_status\": \"ready\", \"report\":   {\"cache_hit\": true, \"created_on\": \"2013-07-29 09:53:44\", \"fact_cache_error\": null, \"fact_cache_hit\": false, \"header_info\": null, \"name\": null, \"report_size\": \"5871\", \"row_count\": \"33\", \"url\": \"report-download?id=2ff62c07fc3653b68f2073e7c1aa0517\"}, \"status\": \"OK\"}}";
ObjectMapper mapper = new ObjectMapper();
ReportResponse reportResponse = mapper.readValue(jsonString, ReportResponse.class);

Caused by: com.fasterxml.jackson.databind.exc.UnrecognizedPropertyException: Unrecognized field "report"

我知道我可以创建一个单独的Report类，然后使用@JsonProperty批注将其嵌入到ReportResponse中。有没有一种方法可以避免这种情况，并使用注释将ReportResponse类标记为可将其映射到JSON中的“report”元素的方法？

最佳答案

还没有注释可以处理这种情况。 There is a ticket requesting this feature.

Here is a brief statement from one of the owners regarding this topic.

引用上述陈述的话:

塔图·萨洛兰塔(Tatu Saloranta):“…@JsonProperty不支持转换，因为数据绑定基于增量解析，并且无法访问完整的树表示形式。支持@JsonUnwrapped是很简单的，但是可行；因此相反(“@JsonWrapped” )从理论上讲是可行的。只需大量工作即可……”