如何在Kotlin中使用Jackson JsonSubTypes批注 [英] How to use Jackson JsonSubTypes annotation in Kotlin

问题描述

我正在尝试转换一些使用Jackson的@JsonSubTypes批注来管理多态性的Java代码.

I'm trying to convert some Java code that uses Jackson's @JsonSubTypes annotation to manage polymorphism.

这是有效的Java代码:

Here is the working Java code:

@JsonTypeInfo(
    use = JsonTypeInfo.Id.NAME,
    include = JsonTypeInfo.As.PROPERTY,
    property = "type")
@JsonSubTypes({
    @JsonSubTypes.Type(value = Comment.class, name = "CommentNote"),
    @JsonSubTypes.Type(value = Photo.class, name = "PhotoNote"),
    @JsonSubTypes.Type(value = Document.class, name = "DocumentNote")
})
public abstract class Note implements Identifiable {
    [...]

以下是我认为等同的Kotlin代码:

Here is the Kotlin code I think would be equivalent:

JsonTypeInfo(
    use = JsonTypeInfo.Id.NAME,
    include = JsonTypeInfo.As.PROPERTY,
    property = "type")
JsonSubTypes(
    JsonSubTypes.Type(value = javaClass<Comment>(), name = "CommentNote"),
    JsonSubTypes.Type(value = javaClass<Photo>(), name = "PhotoNote"),
    JsonSubTypes.Type(value = javaClass<Document>(), name = "DocumentNote")
)
abstract class Note : Identifiable {
    [...]

但是在三条"JsonSubTypes.Type"行中的每行上都出现以下错误:

But I get the following errors on each of the three "JsonSubTypes.Type" lines :

Kotlin: An annotation parameter must be a compile-time constant
Kotlin: Annotation class cannot be instantiated

有什么主意吗?

推荐答案

原来是 bug 在编译器中，感谢您对其进行举报.要变通解决此问题，您可以导入JsonSubTypes.Type并不加限制地使用它:

Turns out it's a bug in the compiler, thanks for reporting it. To work around this issue, you can import JsonSubTypes.Type and use it without qualification:

import org.codehaus.jackson.annotate.JsonSubTypes.Type

JsonTypeInfo(
    use = JsonTypeInfo.Id.NAME,
    include = JsonTypeInfo.As.PROPERTY,
    property = "type")
JsonSubTypes(
    Type(value = javaClass<Comment>(), name = "CommentNote"),
    Type(value = javaClass<Photo>(), name = "PhotoNote"),
    Type(value = javaClass<Document>(), name = "DocumentNote")
)
abstract class Note : Identifiable {
    [...]

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