java - jackson 无法将空字符串值转换为枚举

Question

我正在寻找 Jackson (2.8) 的便捷解决方案，以在反序列化之前/期间过滤掉指向空字符串值的字段:

@JsonInclude(JsonInclude.Include.NON_EMPTY)
public class Guis {

public enum Context {
    SDS,
    NAVIGATION
}

public enum Layer {
    Library,
    Status,
    Drivingdata
}

// client code

 String s = "{\"context\":\"\",\"layer\":\"Drivingdata\"}";
 ObjectMapper mapper = new ObjectMapper();
 Guis o = mapper.readValue(s, Guis.class);

错误

 Exception in thread "main" com.fasterxml.jackson.databind.exc.InvalidFormatException: Can not deserialize value of type cq.speech.rsi.api.Guis$Context from String "": value not one of declared Enum instance names: [SDS NAVIGATION] at [Source: {"context":"","layer":"Drivingdata"}; line: 1, column: 12] (through reference chain: cq.speech.rsi.api.Guis["context"])

我还尝试了什么... 啊这个

mapper.getDeserializationConfig().with(DeserializationFeature.ACCEPT_EMPTY_STRING_AS_NULL_OBJECT);

错误仍然存​​在，显然甚至谷歌搜索也无济于事......

编辑

set DeserializationFeature 不像上面举例的那样工作。对我来说，解决方案最终是添加这个片段:

 mapper.configure(DeserializationFeature.READ_UNKNOWN_ENUM_VALUES_AS_NULL, true)

Answer 1

您可以为映射器启用 DeserializationFeature.READ_UNKNOWN_ENUM_VALUES_AS_NULL，默认情况下禁用。唯一需要注意的是使用它，它将把所有未知的包括空字符串都视为枚举的 null。