java - 使用 @JsonTypeInfo 和 @JsonSubTypes 将 JSON 反序列化为多态对象模型不起作用？

Question

我试图让 REST 端点在 POST 时创建 Widget 的子类型，

这是所有Widget的基类

@JsonTypeInfo(use = JsonTypeInfo.Id.NAME, include = JsonTypeInfo.As.PROPERTY, property = "widgetType")
@JsonSubTypes({
        @JsonSubTypes.Type(value = TextWidget.class, name = WidgetType.Constants.TEXT),
        @JsonSubTypes.Type(value = ImageWidget.class, name = WidgetType.Constants.IMAGE),
        @JsonSubTypes.Type(value = IndicatorWidget.class, name = WidgetType.Constants.INDICATOR),
        @JsonSubTypes.Type(value = MapWidget.class, name = WidgetType.Constants.MAP),
        @JsonSubTypes.Type(value = ChartWidget.class, name = WidgetType.Constants.CHART)
})
@Data
@Slf4j
public abstract class Widget {
...
}

这是 WidgetType 枚举:

public enum WidgetType {
    TEXT(Constants.TEXT),
    IMAGE(Constants.IMAGE),
    INDICATOR(Constants.INDICATOR),
    MAP(Constants.MAP),
    CHART(Constants.CHART);
    private final String type;
    WidgetType(final String type) {
        this.type = type;
    }

    public static class Constants {
        public static final String TEXT = "TEXT";
        public static final String IMAGE = "IMAGE";
        public static final String INDICATOR = "INDICATOR";
        public static final String MAP = "MAP";
        public static final String CHART = "CHART";
    }
}

这是我的 Spring 端点:

@RequestMapping(method = RequestMethod.POST)
public Optional<Widget> createWidget(@Valid final Widget widget) {
    ...
    }

当到达该端点时，它会抛出此异常:

{
  "timestamp": 1493029336774,
  "status": 500,
  "error": "Internal Server Error",
  "exception": "org.springframework.beans.BeanInstantiationException",
  "message": "Failed to instantiate [....models.Widget]: Is it an abstract class?; nested exception is java.lang.InstantiationException",
  "path": "...."
}

浏览了我的问题的几个解决方案，我可能必须手动注册子类型，我可能是错的，但我认为必须有一种方法让它与注释一起工作，也许我错过了一些东西？

Answer 1

问题已解决，我用 Jackson 注释对我的类进行注释，却忘记了我正在发送多部分 POST 请求，这甚至不会发给 Jackson。解决方案很简单:

@RequestMapping(method = RequestMethod.POST)
public Optional<Widget> createWidget(@RequestBody final Widget widget) {
    ...
    }