Question

问题： 创建Include.NON_NULL时是否可以覆盖POJO中定义的ObjectMapper？

说明：

假设我有一个POJO如下：

@JsonInclude(Include.NON_NULL)
class POJO {
  String name;
  String description;
  //Constructors, Getters & Setters, etc
}

如下所示的测试课程：

class Main {
  public static void main(String args[]) {
    POJO p = new POJO();
    ObjectMapper mapper = new ObjectMapper();
     String jsonString = mapper.setSerializationInclusion(Include.ALWAYS)
                               .writerWithDefaultPrettyPrinter()
                               .writeValueAsString(p);
    //jsonString should contain empty name & description fields, but they doesn't
  }
}

Answer 1

您可以使用混合，因为它优先于注释。

@JsonInclude(JsonInclude.Include.ALWAYS)
public class MixIn {
}

并将其添加到映射器

ObjectMapper mapper = new ObjectMapper();
mapper.addMixIn(POJO.class, MixIn.class);

结果将是

{"name":null,"description":null}

在ObjectMapper中覆盖POJO中的@JsonInclude（Include.NON_NULL）

1 个答案: