fastjson2 全局枚举序列化 反序列化

在 fastjson2 中，可以通过实现 SerializerFeature 和 Feature 接口来实现全局枚举的序列化和反序列化。

1. 全局枚举的序列化

可以通过实现 SerializerFeature 接口来实现全局枚举的序列化，例如：

public enum MyEnum {
    A, B, C;
}

public class MyEnumSerializer implements ContextValueSerializer, SerializerFeature {

    @Override
    public void write(JSONSerializer serializer, Object object, Object fieldName, Type fieldType,
                      int features) throws IOException {
        if (object == null) {
            serializer.getWriter().writeNull();
            return;
        }
        Enum<?> e = (Enum<?>) object;
        serializer.getWriter().writeValue(e.ordinal());
    }

    @Override
    public boolean writeAsArray() {
        return false;
    }

    @Override
    public boolean writeNull() {
        return true;
    }

    @Override
    public boolean writeEnumUsingName() {
        return false;
    }

    @Override
    public boolean writeEnumUsingToString() {
        return false;
    }

    @Override
    public boolean writeEnumUsingOrdinal() {
        return true;
    }

    @Override
    public boolean writeSlashAsSpecial() {
        return false;
    }

    @Override
    public boolean writeTabAsSpecial() {
        return false;
    }

    @Override
    public boolean writeQuoteCharAsSpecial() {
        return false;
    }

    @Override
    public boolean writeSingleQuoteAsChar() {
        return false;
    }

    @Override
    public boolean writeClassName() {
        return false;
    }

    @Override
    public boolean notWriteDefaultValue() {
        return false;
    }

    @Override
    public boolean browserSecure() {
        return false;
    }

    @Override
    public boolean writeDateUseDateFormat() {
        return false;
    }

    @Override
    public boolean sortField() {
        return false;
    }

    @Override
    public boolean writeTab() {
        return false;
    }

    @Override
    public boolean prettyFormat() {
        return false;
    }

    @Override
    public boolean writeContentLength() {
        return false;
    }

    @Override
    public boolean quoteFieldNames() {
        return false;
    }

    @Override
    public boolean useSingleQuotes() {
        return false;
    }

    @Override
    public boolean writeNonStringValueAsString() {
        return false;
    }

    @Override
    public boolean notWriteRootClassName() {
        return false;
    }

    @Override
    public boolean beanToArray() {
        return false;
    }

    @Override
    public boolean writeBigDecimalAsPlain() {
        return false;
    }

    @Override
    public boolean ignoreNonFieldGetter() {
        return false;
    }

    @Override
    public boolean writeEnumUsingToStringUsingGlobalSetting() {
        return false;
    }

    @Override
    public boolean writeEnumUsingNameUsingGlobalSetting() {
        return false;
    }

    @Override
    public boolean writeDirect() {
        return false;
    }

    @Override
    public boolean browserCompatible() {
        return false;
    }
}

然后，在初始化 JSON 序列化器时，可以将该序列化器添加到全局的 SerializerFeature 中，例如：

SerializeConfig config = new SerializeConfig();
config.put(MyEnum.class, MyEnumSerializer.INSTANCE);

JSON.DEFAULT_GENERATE_FEATURE |= SerializerFeature.config(JSON.DEFAULT_GENERATE_FEATURE, MyEnum.class);

这样，无论什么时候序列化 MyEnum 类型的枚举值，都会使用 MyEnumSerializer 中定义的方式进行序列化。

2. 全局枚举的反序列化

可以通过实现 Feature 接口来实现全局枚举的反序列化，例如：

public enum MyEnum {
    A, B, C;
}

public class MyEnumFeature implements Feature {

    @Override
    public int getMask() {
        return 0;
    }

    @Override
    public boolean isEnabled(int features) {
        return true;
    }

    @Override
    public boolean isEnabled(int features, int feature) {
        return true;
    }

    @Override
    public int config(int features, int feature, boolean state) {
        if (feature == MyEnumFeature.WRITE_ENUM_USING_ORDINAL.mask) {
            return state ? features | MyEnumFeature.WRITE_ENUM_USING_ORDINAL.mask
                    : features & ~MyEnumFeature.WRITE_ENUM_USING_ORDINAL.mask;
        }
        return features;
    }

    public static final MyEnumFeature WRITE_ENUM_USING_ORDINAL = new MyEnumFeature(1);
    public static final MyEnumFeature WRITE_ENUM_USING_NAME = new MyEnumFeature(2);

    private final int mask;

    private MyEnumFeature(int mask) {
        this.mask = mask;
    }
}

然后，在初始化 JSON 解析器时，可以将该 Feature 添加到全局的 Feature 中，例如：

ParserConfig config = new ParserConfig();
config.addCompatibleFeature(MyEnumFeature.WRITE_ENUM_USING_ORDINAL);

JSON.DEFAULT_PARSER_FEATURE |= MyEnumFeature.WRITE_ENUM_USING_ORDINAL.mask;

这样，无论什么时候反序列化 MyEnum 类型的枚举值，都会使用 MyEnumFeature 中定义的方式进行反序列化。