杰克逊enum序列化和DeSerializer

问题描述

我使用的是JAVA 1.6和Jackson 1.9.9我有一个枚举

I'm using JAVA 1.6 and Jackson 1.9.9 I've got an 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;
    }
}

我添加了一个@JsonValue，做这个工作，将对象序列化为：

I've added a @JsonValue, this seems to do the job it serializes the object into:

{"event":"forgot password"}

但是当我尝试反序列化我得到一个

but when I try to deserialize I get a

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

我在这里缺少什么？

推荐答案

如果您希望将yor枚举类与其JSON表示完全解耦，则xbakesx指出的serializer / deserializer解决方案是一个很好的解决方案。

The serializer / deserializer solution pointed out by xbakesx is an excellent one if you wish to completely decouple yor enum class from its JSON representation.

或者，如果你喜欢自包含的解决方案，基于@JsonCreator和@JsonValue注释的实现将会更加方便。

Alternatively, if you prefer a self-contained solution, an implementation based on @JsonCreator and @JsonValue annotations would be more convenient.

所以利用S的例子以下是一个完整的独立解决方案（Java 6，Jackson 1.9）：

So leveraging on the example by Stanley the following is a complete self-contained solution (Java 6, Jackson 1.9):

public enum DeviceScheduleFormat {
    Weekday,
    EvenOdd,
    Interval;

    private static Map<String, DeviceScheduleFormat> namesMap = new HashMap<String, DeviceScheduleFormat>(3);

    static {
        namesMap.put("weekday", Weekday);
        namesMap.put("even-odd", EvenOdd);
        namesMap.put("interval", Interval);
    }

    @JsonCreator
    public static DeviceScheduleFormat forValue(String value) {
        return namesMap.get(StringUtils.lowerCase(value));
    }

    @JsonValue
    public String toValue() {
        for (Entry<String, DeviceScheduleFormat> entry : namesMap.entrySet()) {
            if (entry.getValue() == this)
                return entry.getKey();
        }

        return null; // or fail
    }
}

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