java - Jackson 具有抽象类的多态行为

Question

有一个包含各种字段的类DocumentMapping。这些字段之一是抽象类 BinaryDocumentMapping。 BinaryDocumentMapping 由其他 3 个类 ExcelDocumentMapping、XMLDocumentMapping 和 CSVDocumentMapping 扩展。

所以我有:

public class DocumentMapping{

    @JsonSubTypes({ @JsonSubTypes.Type(value = ExcelDocumentMapping.class, name = "EXCEL"),
            @JsonSubTypes.Type(value = CsvDocumentMapping.class, name = "CSV"), @JsonSubTypes.Type(value = XmlDocumentMapping.class, name = "XML") })
    private BinaryDocumentMapping binary = null;

哪里

public abstract class BinaryDocumentMapping
    implements Serializable {

和

@JsonTypeName("CSV")
public class CsvDocumentMapping

序列化工作正常，但在将 json 读入对象时遇到问题:

mapper.reader().withType(DocumentMapping.class).readValue(jsonData);

抛出

com.fasterxml.jackson.databind.JsonMappingException: Can not construct instance of com.documentmapping.BinaryDocumentMapping, problem: abstract types either need to be mapped to concrete types, have custom deserializer, or be instantiated with additional type information

有没有办法根据类型反序列化为具体类？

Answer 1

您需要指定@JsonTypeInfo看stackoverflow.com/a/11798485/1976843