没有任何JsonIncludeconfiguration的字段。对，但是无论Java将其初始化为null还是我显式将其设置为null，它都会序列化null字段。我想我需要要么让可选值正常工作，要么拿出不为null的默认值（因为Jackson显然无法区分两者

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没有任何

JsonInclude

configuration的字段。对，但是无论Java将其初始化为null还是我显式将其设置为null，它都会序列化null字段。我想我需要要么让可选值正常工作，要么拿出不为null的默认值（因为Jackson显然无法区分两者之间的区别）。问题是对于原语，null、0和非零都是有效值，所以我不知道默认值应该使用什么。在这种情况下，请看答案。另外，我不建议在被反序列化的类中使用原语，因为它会抛出一个

NPE

is对应值，在json中为

null

。我实际上正在尝试进行部分更新。感谢您的回答，我将寻找一种不同的方法。使用2.9.6版本测试，仅使用jdk8模块，可选的工作方式与预期一致。不需要参数名模块

class Data {
  public String string;
  public String other;
}

Data data = new Data();
ObjectMapper mapper = new ObjectMapper();
System.out.println(mapper.writeValueAsString(data));

{"string":null,"other":null}

Data data = new Data("value", null);
ObjectMapper mapper = new ObjectMapper();
System.out.println(mapper.writeValueAsString(data));

{"string":"value"}

@JsonInclude(Include.NON_NULL)
class IgnoreNullFields
{
  String someString;
}

// object Mapper
ObjectMapper mapper = new ObjectMapper()
               .registerModule(new Jdk8Module())
               .registerModule(new ParameterNamesModule())
               .registerModule(new JavaTimeModule());


// DTO
@Data
@ToString
@JsonInclude(JsonInclude.Include.NON_NULL)
// employee object in producer
public class PEmployee {
    private Optional<String> name;
    private Optional<Integer> age;
    private Optional<BigDecimal> salary;
    private Optional<Boolean> active;
    private Optional<LocalDate> dateOfJoining;
}

// serialize before sending it
PEmployee emp = new PEmployee();
emp.setActive(Optional.ofNullable(Boolean.FALSE));
emp.setName(Optional.of("Johnson"));
emp.setDateOfJoining(Optional.empty());

// PEmployee(name=Optional[Johnson], age=null, 
//salary=null, active=Optional[false], dateOfJoining=Optional.empty)

String payload = mapper.writeValueAsString(emp);
// {"name":"Johnson","active":false,"dateOfJoining":null}

// DTO
@Data
@ToString
public class CEmployee {
    private Optional<String> name;
    private Optional<Integer> age;
    private Optional<BigDecimal> salary;
    private Optional<Boolean> active;
    private Optional<LocalDate> dateOfJoining;
}

// deserialize
CEmployee emp = mapper.readValue(payload, CEmployee.class);

// CEmployee(name=Optional[Johnson], age=null, 
// salary=null, active=Optional[false], dateOfJoining=Optional.empty)

    <dependency>
        <groupId>com.fasterxml.jackson.module</groupId>
        <artifactId>jackson-module-parameter-names</artifactId>
        <version>2.8.10</version>
    </dependency>
    <dependency>
        <groupId>com.fasterxml.jackson.datatype</groupId>
        <artifactId>jackson-datatype-jdk8</artifactId>
        <version>2.8.10</version>
    </dependency>
    <dependency>
        <groupId>com.fasterxml.jackson.datatype</groupId>
        <artifactId>jackson-datatype-jsr310</artifactId>
        <version>2.8.10</version>
    </dependency>