如何在 JAVA 中忽略 NullNode for deserialization JSON

Question

所以问题是下一个：我有POJO，比如：

@Data

@Accessors(chain = true)

@JsonInclude(Include.NON_NULL)

public class TestPOJO {

  private Long id;

  private String name;

  private JsonNode jsonNode;

我也有json喜欢

{

   "id":1

   "name": "foo"

   "jsonNode":null

}

当我尝试反序列化最后一个

ObjectMapper objectMapper = new ObjectMapper();

TestPOJO testPojo = objectMapper.readValue(<json String>, TestPOJO.class);

我在字段所在的位置获取对象，但我需要在如何修复它？testPojojsonNodeNullNodetestPojo == null

Answer 1

添加一个扩展的类，如果为 null，则返回 null：JsonDeserializer<JsonNode>parser.getText()import com.fasterxml.jackson.core.JsonParser;import com.fasterxml.jackson.databind.DeserializationContext;import com.fasterxml.jackson.databind.JsonDeserializer;import com.fasterxml.jackson.databind.JsonNode;import java.io.IOException;public class JsonNodeDeserializer extends JsonDeserializer<JsonNode> {&nbsp; &nbsp; @Override&nbsp; &nbsp; public JsonNode deserialize(JsonParser parser, DeserializationContext context)&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; throws IOException {&nbsp; &nbsp; &nbsp; &nbsp; String value = parser.getText();&nbsp; &nbsp; &nbsp; &nbsp; if(value == null) {&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; return null;&nbsp; &nbsp; &nbsp; &nbsp; }&nbsp; &nbsp; &nbsp; &nbsp; return (JsonNode) context.findRootValueDeserializer(context.constructType(JsonNode.class)).deserialize(parser, context);&nbsp; &nbsp; }}然后对属性进行注释，以告诉 Jackson 使用您的自定义反序列化程序：jsonNode@JsonDeserialize(using = JsonNodeDeserializer.class)@Data@Accessors(chain = true)@JsonInclude(Include.NON_NULL)public class TestPOJO {&nbsp; private Long id;&nbsp; private String name;&nbsp; @JsonDeserialize(using = JsonNodeDeserializer.class)&nbsp; private JsonNode jsonNode;&nbsp; // getters and setters}