java - 改进了使用 Jackson 将嵌套 JSON 对象的 boolean 值转换为 Map 的方法

Question

我有以下 JSON 对象

{
  "donor": "Y",
  "bloodType": null,
  "eligibility": {
    "categoryEligible": false,
    "suspensionEligible": false,
    "paidFinesEligible": false,
    "pointSystemEligible": false,
    "failedDocuments": [
      {
        "type": "SOMETHING",
        "reason": "SOMETHING_ELSE"
      }
    ],
    "eligible": false,
  }
}

我正在使用 Jackson 将其转换为我的域对象。以下是我正在使用的字段:

    private String donor;

    @JsonProperty("eligibility")
    private Eligibility eligibility;

Eligibility 类包含所有这些字段，我不想为所有 boolean 值设置单独的字段，而是拥有一个 Map< String, Boolean > 其中 String 是属性名称和 boolean 值是值。

    @JsonProperty("failedDocuments")
    private List<FailedDocumentsItem> failedDocuments;

    @JsonProperty("eligible")
    private boolean eligible;

    @JsonProperty("donor")
    private boolean donor;

Answer 1

添加 @JsonAnySetter字段(Jackson 2.8+)或方法:

Marker annotation that can be used to define a logical "any setter" mutator -- either using non-static two-argument method (first argument name of property, second value to set) or a field (of type Map or POJO) - to be used as a "fallback" handler for all otherwise unrecognized properties found from JSON content.

为简洁起见，使用公共(public)字段的示例。

public class Test {
    public static void main(String[] args) throws Exception {
        ObjectMapper mapper = new ObjectMapper();
        Root root = mapper.readValue(new File("test.json"), Root.class);
        System.out.println("donor = " + root.donor);
        System.out.println("flags = " + root.eligibility.flags);
        System.out.println("failedDocuments = " + root.eligibility.failedDocuments);
    }
}
class Root {
    public Boolean realId;
    public String donor;
    public Boolean bloodType;
    public Boolean selectiveServiceCandidate;
    public Eligibility eligibility;
}
class Eligibility {
    @JsonAnySetter
    public Map<String, Boolean> flags = new HashMap<>();
    public List<FailedDocument> failedDocuments;
}
class FailedDocument {
    public String type;
    public String reason;
    @Override
    public String toString() {
        return "FailedDocument[type=" + this.type + ", reason=" + this.reason + "]";
    }
}

输出

donor = Y
flags = {paidFinesEligible=false, hasRealId=false, suspensionEligible=false, acaaEligible=false, eligibleIgnoreRenewalDate=false, eligibleDocuments=false, cardStatusEligible=false, expirationDateEligible=false, eligible=false, citizenEligible=false, pointSystemEligible=false, ageEligible=false, gravamenesEligible=false, categoryEligible=false, eligibleMedical=false}
failedDocuments = [FailedDocument[type=CERTIFICATE_CITIZENSHIP, reason=MISSING]]