我目前正在使用杰克逊2.1.4,并且在将对象转换为JSON字符串时忽略字段时遇到了一些麻烦。
这是我的类,它充当要转换的对象:
public class JsonOperation { public static class Request { @JsonInclude(Include.NON_EMPTY) String requestType; Data data = new Data(); public static class Data { @JsonInclude(Include.NON_EMPTY) String username; String email; String password; String birthday; String coinsPackage; String coins; String transactionId; boolean isLoggedIn; } } public static class Response { @JsonInclude(Include.NON_EMPTY) String requestType = null; Data data = new Data(); public static class Data { @JsonInclude(Include.NON_EMPTY) enum ErrorCode { ERROR_INVALID_LOGIN, ERROR_USERNAME_ALREADY_TAKEN, ERROR_EMAIL_ALREADY_TAKEN }; enum Status { ok, error }; Status status; ErrorCode errorCode; String expiry; int coins; String email; String birthday; String pictureUrl; ArrayList <Performer> performer; } } }
这是我如何转换它:
ObjectMapper mapper = new ObjectMapper(); mapper.setVisibility(PropertyAccessor.FIELD, Visibility.ANY); JsonOperation subscribe = new JsonOperation(); subscribe.request.requestType = "login"; subscribe.request.data.username = "Vincent"; subscribe.request.data.password = "test"; Writer strWriter = new StringWriter(); try { mapper.writeValue(strWriter, subscribe.request); } catch (JsonGenerationException e) { // TODO Auto-generated catch block e.printStackTrace(); } catch (JsonMappingException e) { // TODO Auto-generated catch block e.printStackTrace(); } catch (IOException e) { // TODO Auto-generated catch block e.printStackTrace(); } Log.d("JSON", strWriter.toString())
这是输出:
{"data":{"birthday":null,"coins":null,"coinsPackage":null,"email":null,"username":"Vincent","password":"test","transactionId":null,"isLoggedIn":false},"requestType":"login"}
如何避免这些空值?我只想获取“订阅”目的所需的信息!
这正是我要查找的输出:
{"data":{"username":"Vincent","password":"test"},"requestType":"login"}
我还尝试了@JsonInclude(Include.NON_NULL)并将所有变量都设置为null,但是它也不起作用!感谢您的帮助!
您将注解放置在错误的位置-注解必须在类上,而不是在字段上。即:
@JsonInclude(Include.NON_NULL) //or Include.NON_EMPTY, if that fits your use case public static class Request { // ... }
如注释中所述,在2.x以下的版本中,此注释的语法为:
@JsonSerialize(include = JsonSerialize.Inclusion.NON_NULL) // or JsonSerialize.Inclusion.NON_EMPTY
另一种选择是ObjectMapper直接配置,只需调用 mapper.setSerializationInclusion(Include.NON_NULL);
ObjectMapper
mapper.setSerializationInclusion(Include.NON_NULL);
(为了便于记录,我认为此答案的流行程度表明该注释 应 在逐个字段的基础上应用@fasterxml)