带有参数的 Scala 2.11 反射和注释(Java) [英] Scala 2.11 reflection and annotations (Java) with parameters

问题描述

我有一个用 Java 编写的简单类级注释:

I have a simple class-level annotation written in Java:

@Target({ElementType.TYPE})
@Retention(RetentionPolicy.RUNTIME)
public @interface Collection {
    String name();
}

用于:

@Collection(name="mytable")
case class Foo(...)

我需要内省 Scala 2.11 中的类以获取 name 参数的值.我怎样才能得到这些信息?我到此为止:

I need to introspect classes in Scala 2.11 to obtain the value of the name parameter. How can I get this info? I'm up to here:

val sym = currentMirror.classSymbol(Class.forName(fullName))
val anno = sym.annotations.head
val annoType = anno.tree.tpe  // I can get this...works
println(anno.tree.children.tail)  // prints List(name = "mytable")

我很接近！我可以看到我的 name 参数及其值，但这似乎不像 Map 或任何友好的东西那样可以访问.如何获取注释参数的值?

I'm close! I can see my name parameter and its value but this doesn't seem to be accessible like a Map or anything friendly. How can I get the value of my annotation's parameter?

推荐答案

tree api 实现了 product 来获取元素，所以这有点像hacky 演示，但是你可以获取你的元素:

The tree api implements product to get elements out, so this is kind of a hacky demonstration, but you can get out your element:

  println(anno.tree.children.last.productElement(1))  // prints "mytable"

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