Jackson序列化:忽略空值(或null)

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!

这正是我要寻找的输出:

{"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!

回答:

你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);

以上是 Jackson序列化:忽略空值(或null) 的全部内容, 来源链接: utcz.com/qa/432556.html

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