Question

我正在尝试在注释属性上放置注释。我的理解是，我应该可以通过代码访问它-但我不能。我想念什么？

package com.example.annotations

import org.junit.jupiter.api.Assertions
import org.junit.jupiter.api.Test
import kotlin.reflect.full.findAnnotation

class AnnotationIssueTest {
    @Test
    fun testAnnotations() {
        Assertions.assertNotNull(MyTestAnnotation::value.findAnnotation<PropertyMarker>())
    }

    @Test
    fun testRegularClass() {
        Assertions.assertNotNull(MyTestClass::value.findAnnotation<PropertyMarker>())
    }
}


@Retention(AnnotationRetention.RUNTIME)
@Target(AnnotationTarget.PROPERTY)
annotation class PropertyMarker

annotation class MyTestAnnotation(
        @PropertyMarker val value: String
)

class MyTestClass(
        @PropertyMarker val value: String
)

运行给定测试时，testAnnotations失败，而testRegularClass通过。这是错误还是我做错了什么？

Answer 1

由于某些原因，注释属性的注释未进入字节码。但是，您可以改为注释属性获取器：

class AnnotationIssueTest {
    @Test
    fun testAnnotations() {
        Assertions.assertNotNull(MyTestAnnotation::value.getter.findAnnotation<PropertyMarker>())
    }

    @Test
    fun testRegularClass() {
        Assertions.assertNotNull(MyTestClass::value.getter.findAnnotation<PropertyMarker>())
    }
}


@Retention(AnnotationRetention.RUNTIME)
@Target(AnnotationTarget.PROPERTY_GETTER)
annotation class PropertyMarker

annotation class MyTestAnnotation(
        @get:PropertyMarker val value: String
)

class MyTestClass(
        @get:PropertyMarker val value: String
)

如何在Kotlin中注释注释属性？

1 个答案: