Jackson枚举序列化和反序列化器

Question

我正在使用JAVA 1.6和Jackson 1.9.9我有一个枚举

public enum Event {

    FORGOT_PASSWORD("forgot password");

    private final String value;

    private Event(final String description) {

        this.value = description;

    }

    @JsonValue

    final String value() {

        return this.value;

    }

}

我添加了一个@JsonValue，这似乎可以将对象序列化为：

{"event":"forgot password"}

但是当我尝试反序列化时，我得到了

Caused by: org.codehaus.jackson.map.JsonMappingException: Can not construct instance of com.globalrelay.gas.appsjson.authportal.Event from String value 'forgot password': value not one of declared Enum instance names

我在这里想念什么？

Answer 1

请注意，自2015年6月提交此内容（杰克逊2.6.2及更高版本）起，您现在可以简单地编写：public enum Event {    @JsonProperty("forgot password")    FORGOT_PASSWORD;}

Answer 2

实际答案：枚举的默认反序列化器用于.name()反序列化，因此不使用@JsonValue。因此，正如@OldCurmudgeon指出的那样，您需要传递{"event": "FORGOT_PASSWORD"}以匹配该.name()值。另一个选项（假设您希望写入和读取json值相同）...更多信息：（还有）另一种使用Jackson来管理序列化和反序列化过程的方法。您可以指定以下批注以使用自己的自定义序列化器和反序列化器：@JsonSerialize(using = MySerializer.class)@JsonDeserialize(using = MyDeserializer.class)public final class MyClass {&nbsp; &nbsp; ...}然后，你必须编写MySerializer和MyDeserializer它看起来像这样：MySerializerpublic final class MySerializer extends JsonSerializer<MyClass>{&nbsp; &nbsp; @Override&nbsp; &nbsp; public void serialize(final MyClass yourClassHere, final JsonGenerator gen, final SerializerProvider serializer) throws IOException, JsonProcessingException&nbsp; &nbsp; {&nbsp; &nbsp; &nbsp; &nbsp; // here you'd write data to the stream with gen.write...() methods&nbsp; &nbsp; }}MyDeserializerpublic final class MyDeserializer extends org.codehaus.jackson.map.JsonDeserializer<MyClass>{&nbsp; &nbsp; @Override&nbsp; &nbsp; public MyClass deserialize(final JsonParser parser, final DeserializationContext context) throws IOException, JsonProcessingException&nbsp; &nbsp; {&nbsp; &nbsp; &nbsp; &nbsp; // then you'd do something like parser.getInt() or whatever to pull data off the parser&nbsp; &nbsp; &nbsp; &nbsp; return null;&nbsp; &nbsp; }}最后一点，特别是对于对JsonEnum使用该方法进行序列化的枚举执行此操作时getYourValue()，您的序列化器和反序列化器可能如下所示：public void serialize(final JsonEnum enumValue, final JsonGenerator gen, final SerializerProvider serializer) throws IOException, JsonProcessingException{&nbsp; &nbsp; gen.writeString(enumValue.getYourValue());}public JsonEnum deserialize(final JsonParser parser, final DeserializationContext context) throws IOException, JsonProcessingException{&nbsp; &nbsp; final String jsonValue = parser.getText();&nbsp; &nbsp; for (final JsonEnum enumValue : JsonEnum.values())&nbsp; &nbsp; {&nbsp; &nbsp; &nbsp; &nbsp; if (enumValue.getYourValue().equals(jsonValue))&nbsp; &nbsp; &nbsp; &nbsp; {&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; return enumValue;&nbsp; &nbsp; &nbsp; &nbsp; }&nbsp; &nbsp; }&nbsp; &nbsp; return null;}