java - 返回带有键值对的 JSON

Question

我使用此代码从 REST 端点生成响应:

if (result.hasErrors()) {
            List<String> errorsList = new ArrayList<>();
            List<FieldError> errors = result.getFieldErrors();
            for (FieldError error : errors ) {
                System.out.println("Validation error in field: " + error.getObjectName() 
                               + "! Validation error message: " + error.getDefaultMessage() 
                               + "! Rejected value:" + error.getRejectedValue());
                errorsList.add(error.getField() + ": " + error.getDefaultMessage());
            }

            return ResponseEntity.ok(new StringResponseDTO(errorsList));
        }

对象:

@JsonTypeInfo(include = JsonTypeInfo.As.WRAPPER_OBJECT, use = JsonTypeInfo.Id.NAME)
@JsonTypeName("response")
public class StringResponseDTO {

    private String redirect;

    private List<String> errors;

    public StringResponseDTO(String redirect) {
        super();
        this.redirect = redirect;
    }

    public StringResponseDTO(List<String> errors) {
        this.errors = errors;
    }

    ......
}

现在我得到这样的回复:

{
  "response" : {
    "errors" : [ "expiration_year: must not be null", "default_transaction_type: must not be null"]
  }
}

我需要像这样更改它:

{
      "response" : {
        "errors" : [ "expiration_year": "must not be null", "default_transaction_type": "must not be null"]
      }
    }

有没有办法在不添加大量“”符号的情况下存档他的内容？

Answer 1

您在“想要的”结果中表达的格式无效。
例如，您可以使用 Jackson(或 GSON，具体取决于您使用的库)类

(注意， objectMapper 是 ObjectMapper 的实例)

public class StringResponseDTO {
    private String redirect;
    private TreeNode errors;

    public StringResponseDTO(final String redirect) {
        this.redirect = redirect;
    }

    public StringResponseDTO(final Collection<? extends FieldError> errors) {
        this.errors =
                errors.stream()
                      .collect(Collector.of(
                              objectMapper::createObjectNode,
                              (json, e) -> json.put(e.getField(), e.getDefaultMessage()),
                              (json, toMerge) -> {
                                  json.setAll(toMerge);
                                  return json;
                              }
                      ));
    }

    public String getRedirect() {
        return redirect;
    }

    public TreeNode getErrors() {
        return errors;
    }
}

这将被序列化为

{
    "redirect": "...",
    "errors": {
        "field1": "err field1",
        "field2": "err field2",
        "field3": "err field3"
    }
}

<小时/>

或者，如果您愿意，也可以使用通常的 Map<String, String>解决方案。

public class StringResponseDTO {
    private String redirect;
    private Map<String, String> errors;

    public StringResponseDTO(final String redirect) {
        this.redirect = redirect;
    }

    public StringResponseDTO(final Collection<? extends FieldError> errors) {
        this.errors =
                errors.stream()
                      .collect(Collectors.toMap(
                              FieldError::getField,
                              FieldError::getDefaultMessage
                      ));
    }

    public String getRedirect() {
        return redirect;
    }

    public Map<String, String> getErrors() {
        return errors;
    }
}

这会输出相同的内容

{
    "redirect": "...",
    "errors": {
        "field1": "err field1",
        "field2": "err field2",
        "field3": "err field3"
    }
}

<小时/>

这取决于你。