mapper.readValue() return null value (Jackson API)

Question

我有一个JSON对象，我正在尝试从Jackson API对象映射器读取。

{  
   "ddt_id":"605",
   "ddt_batch_code":"5769005b-e8f0-4ae8-8971-1c59ac1f02fd",
   "keyword":"ADP",
   "keyword_operation":"and",
   "keyword_extract_match":"F",
   "search_in":"name",
   "filter_type":"entity,others",
   "category":"2,3,5",
   "gender":"",
   "date_year":"",
   "date_month":"",
   "date_day":"",
   "country":"",
   "search_filter_uuid":"570bd722-315c-40b3-b2d6-4522ac1f02fd",
   "ddt_qsk_question":"0",
   "search_for":"all",
   "search_category":"2,3,5",
   "search_includes_name":"T",
   "search_includes_profile_notes":"F",
   "search_for_person":"F",
   "search_for_entity":"T",
   "search_for_others":"T",
   "search_from_module":"DDMT.V.2.20",
   "client_id":667,
   "ip_address":"52.23.94.13",
   "search_requester_id":false,
   "search_requester_name":false,
   "batch_id":"5769005b-e8f0-4ae8-8971-1c59ac1f02fd",
   "person_query_index":4,
   "company_query_index":4,
   "is_ongoing":1
}

我用来在对象中读取此 JSON 的类是：

import com.fasterxml.jackson.annotation.JsonIgnoreProperties;
import com.fasterxml.jackson.annotation.JsonInclude;
import com.fasterxml.jackson.annotation.JsonProperty;
import java.util.UUID;
@JsonInclude(JsonInclude.Include.NON_NULL)
@JsonIgnoreProperties(ignoreUnknown = true)
public class SswltSearchParams {
    @JsonProperty("batch_id")
    private UUID batchId;
    @JsonProperty("country")
    private String country;
    @JsonProperty("criteria_id")
    private String id;
    @JsonProperty("date_day")
    private Integer day;
    @JsonProperty("date_month")
    private Integer month;
    @JsonProperty("date_year")
    private Integer year;
    @JsonProperty("gender")
    private String gender;
    @JsonProperty("keyword")
    private String keyword;
    @JsonProperty("keyword_exact_match")
    private String keywordExactMatch;
    @JsonProperty("keyword_operation")
    private String keywordOperation;
    @JsonProperty("search_category")
    private String searchCategory;
    @JsonProperty("search_for")
    private String searchFor;
    @JsonProperty("search_for_anti_corruption")
    private String searchForAntiCorruption;
    @JsonProperty("search_for_entity")
    private String searchForEntity;
    @JsonProperty("search_for_others")
    private String searchForOthers;
    @JsonProperty("search_for_person")
    private String searchForPerson;
    @JsonProperty("search_for_watchlist")
    private String searchForWatchlist;
    @JsonProperty("search_includes_name")
    private String searchIncludesName;
    @JsonProperty("search_includes_profile_notes")
    private String searchIncludesProfileNotes;
    @JsonProperty("update_only")
    private String updateOnly;
   // getters and setters
}

当我尝试将此 JSON 放在 Onject 中时，我没有收到任何错误，但我得到了 NULL 值。

try {
            SswltMigrationCollection sswltSearchParams = mapper.readValue(searchCriteria.getScrCriteria(), SswltSearchParams.class);
        } catch (IOException e) {
            return null;
        }

为什么我把这个sswltSearchParams作为null？请帮忙。

Answer 1

您的 JSON 可以解析为SswltSearchParams实例，没有任何问题。以下代码工作正常：

String json = "{"ddt_id":"605","ddt_batch_code":"5769005b-e8f0-4ae8-8971-1c59ac1f02fd","keyword":"ADP","keyword_operation":"and","keyword_extract_match":"F","search_in":"name","filter_type":"entity,others","category":"2,3,5","gender":"","date_year":"","date_month":"","date_day":"","country":"","search_filter_uuid":"570bd722-315c-40b3-b2d6-4522ac1f02fd","ddt_qsk_question":"0","search_for":"all","search_category":"2,3,5","search_includes_name":"T","search_includes_profile_notes":"F","search_for_person":"F","search_for_entity":"T","search_for_others":"T","search_from_module":"DDMT.V.2.20","client_id":667,"ip_address":"52.23.94.13","search_requester_id":false,"search_requester_name":false,"batch_id":"5769005b-e8f0-4ae8-8971-1c59ac1f02fd","person_query_index":4,"company_query_index":4,"is_ongoing":1}";
ObjectMapper mapper = new ObjectMapper();
SswltSearchParams sswltSearchParams = mapper.readValue(json, SswltSearchParams.class);

不知道为什么SswltMigrationCollection课开始发挥作用。