我使用JAVA 1.6和Jackson 1.9.9,我有一个enum

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;
    }
}

我已经添加了一个@JsonValue,这似乎做的工作,它序列化对象:

{"event":"forgot password"}

但当我尝试反序列化时,我得到

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

我错过了什么?


当前回答

我发现最简单的方法是使用@JsonFormat.Shape。枚举的OBJECT注释。

@JsonFormat(shape = JsonFormat.Shape.OBJECT)
public enum MyEnum{
    ....
}

其他回答

@JsonFormat(shape = JsonFormat.Shape.OBJECT)
public enum LoginOptionType {

 PHONE(1, "Phone"), MAIL(2, "mail"), PERSONAL_EMAIL(3, "Personal email");

private static List<LoginOptionType> all;

static {
    all = new ArrayList<LoginOptionType>() {
        {
            add(LoginOptionType.PHONE);
            add(LoginOptionType.MAIL);
            add(LoginOptionType.PERSONAL_EMAIL);
        }
    };
}

private final Integer viewValue;

private final String name;

LoginOptionType(Integer viewValue, String name) {
    this.viewValue = viewValue;
    this.name = name;
}

public Integer getViewValue() {
    return viewValue;
}

public String getName() {
    return name;
}

public static List<LoginOptionType> getAll() {
    return all;
}
}

响应

[
{
    "viewValue": 1,
    "name": "Phone"
},
{
    "viewValue": 2,
    "name": "mail"
},
{
    "viewValue": 3,
    "name": "Personal email"
}
]

我发现最简单的方法是使用@JsonFormat.Shape。枚举的OBJECT注释。

@JsonFormat(shape = JsonFormat.Shape.OBJECT)
public enum MyEnum{
    ....
}

我一直在寻找枚举序列化的解决方案,我终于做出了一个解决方案。

https://github.com/sirgilligan/EnumerationSerialization

https://digerati-illuminatus.blogspot.com/2022/10/java-enum-generic-serializer-and.html

它使用了一个新的注释和两个新类EnumerationSerializer和EnumerationDeserializer。您可以子类化EnumerationDeserializer,并创建一个设置枚举class的类(典型方法),或者您可以注释枚举,并且不必拥有EnumerationDeserializer的子类。

@JsonSerialize(using = EnumerationSerializer.class)
@JsonDeserialize(using = EnumerationDeserializer.class)
@EnumJson(serializeProjection = Projection.NAME, deserializationClass = RGB.class)
enum RGB {
    RED,
    GREEN,
    BLUE
}

注意ContextualDeserializer的实现如何从注释中提取类。

https://github.com/sirgilligan/EnumerationSerialization/blob/main/src/main/java/org/example/EnumerationDeserializer.java

这里有很多很好的代码,可以提供一些见解。

对于你的具体问题,你可以这样做:

@JsonSerialize(using = EnumerationSerializer.class)
@JsonDeserialize(using = EnumerationDeserializer.class)
@EnumJson(serializeProjection = Projection.NAME, deserializationClass = Event.class)
public enum Event {
    FORGOT_PASSWORD("forgot password");

    //This annotation is optional because the code looks for value or alias.
    @EnumJson(serializeProjection = Projection.VALUE)
    private final String value;

    private Event(final String description) {
        this.value = description;
    }

}

或者你可以这样做:

@JsonSerialize(using = EnumerationSerializer.class)
@JsonDeserialize(using = EnumerationDeserializer.class)
@EnumJson(serializeProjection = Projection.NAME, deserializationClass = Event.class)
public enum Event {
    FORGOT_PASSWORD("forgot password");

    private final String value;

    private Event(final String description) {
        this.value = description;
    }

}

这就是你要做的。

然后,如果您有一个“有”事件的类,您可以注释每个事件以您想要的方式序列化。

class EventHolder {
    @EnumJson(serializeProjection = Projection.NAME)
    Event someEvent;

    @EnumJson(serializeProjection = Projection.ORDINAL)
    Event someOtherEvent;

    @EnumJson(serializeProjection = Projection.VALUE)
    Event yetAnotherEvent;
}

您可以自定义任何属性的反序列化。

使用将要处理的属性的annotationJsonDeserialize (import com.fasterxml.jackson.databin .annotation. jsondeserialize)声明反序列化类。如果这是一个Enum:

@JsonDeserialize(using = MyEnumDeserialize.class)
private MyEnum myEnum;

通过这种方式,您的类将被用于反序列化属性。这是一个完整的例子:

public class MyEnumDeserialize extends JsonDeserializer<MyEnum> {

    @Override
    public MyEnum deserialize(JsonParser jsonParser, DeserializationContext deserializationContext) throws IOException {
        JsonNode node = jsonParser.getCodec().readTree(jsonParser);
        MyEnum type = null;
        try{
            if(node.get("attr") != null){
                type = MyEnum.get(Long.parseLong(node.get("attr").asText()));
                if (type != null) {
                    return type;
                }
            }
        }catch(Exception e){
            type = null;
        }
        return type;
    }
}

试试这个。

public enum Event {

    FORGOT_PASSWORD("forgot password");

    private final String value;

    private Event(final String description) {
        this.value = description;
    }

    private Event() {
        this.value = this.name();
    }

    @JsonValue
    final String value() {
        return this.value;
    }
}