scala reflection miss inherit class java annotation

Question

model code(partly):

@Documented
@Retention(RetentionPolicy.RUNTIME)
@Target(ElementType.FIELD)
public @interface CoreField {

  String mongoTag() default "";

  boolean needIndex() default false;
}


trait PackItemTrait {

  @BeanProperty
  @CoreField(mongoTag = "num")
  var number: Int = _
}


class UserResourceFragmentT_1 {

  @BeanProperty
  @CoreField(mongoTag = "num")
  var number: Int = _
}


class UserResourceFragmentT_2 extends PackItemTrait {

}

reflection code(partly):

val className = "xxx.xxxx.UserResourceFragmentT_1" // or UserResourceFragmentT_2 fullNme
val clzSymbol = mirror.staticClass(className)
val clzType = clzSymbol.toType
clzType.members.foreach { each =>
  if (each.isTerm) {
    val eachTerm = each.asTerm
    println("eachTerm:" + eachTerm.name.decoded)
    println("isAccessor:" + eachTerm.isAccessor)
    println("isGetter:" + eachTerm.isGetter)
    println("isSetter:" + eachTerm.isSetter)
    println("isVar:" + eachTerm.isVar)
    println("isVal:" + eachTerm.isVal)
    println("annotation size:" + eachTerm.annotations.size)
    println("")
    if (eachTerm.isVar || eachTerm.isVal) {

I test class UserResourceFragmentT_1 and UserResourceFragmentT_2. When reflect UserResourceFragmentT_1, the outprint annotation size is 2, that's right, on the other hand, when reflect UserResourceFragmentT_2 which is inherit trait class PackItemTrait, the field number could be parse, but print is not like to previous model.

println:

UserResourceFragmentT_1

[info] eachTerm:number
[info] isAccessor:false
[info] isGetter:false
[info] isSetter:false
[info] isVar:true
[info] isVal:false
[info] annotation size:2

[info] eachTerm:number_=
[info] isAccessor:true
[info] isGetter:false
[info] isSetter:true
[info] isVar:false
[info] isVal:false
[info] annotation size:0

UserResourceFragmentT_2

[info] eachTerm:number_=
[info] isAccessor:true
[info] isGetter:false
[info] isSetter:true
[info] isVar:false
[info] isVal:false
[info] annotation size:0

[info] eachTerm:number
[info] isAccessor:true
[info] isGetter:true
[info] isSetter:false
[info] isVar:false
[info] isVal:false
[info] annotation size:0

I don't really konw about scala inherit mechanism... I also test PackItemTrait as abstract class, normal class, case class, the result are same: scala reflection api can not parse java annotation with field which inherit from super class, Any one can help me???

Could you upload the entire project to github? I'll be glad to take a look. — Eugene Burmako
There is too much code for entire project, i am not sure you can compile them in sbt easily, it cannot done easily. my problem is easy to reporduce. — Mars
@EugeneBurmako it is simple to reproduce, runtimeMirror(clazz.getClassLoader).classSymbol(clazz).selfType.members returns all members including the inherited ones. The problem is that calling m.annotations on those inherited members return empty List even though they are annotated... — lisak

Mars Mars · Accepted Answer · 2014-04-13T05:51:59

After some research, I find a way to go:

val mirror = ru.runtimeMirror(Thread.currentThread.getContextClassLoader)
  val clzSymbol = mirror.staticClass("xxx.XXX.UserEquipmentT")
  clzSymbol.baseClasses.filter(
    each => (each.name.decoded != "Any" && each.name.decoded != "Object")
  ).foreach { each =>
    each.asType.toType.members.foreach { each =>
      if (each.isTerm) {
        val eachTerm = each.asTerm
        if (eachTerm.isVal || eachTerm.isVar) {
          println("name:" + eachTerm.name.decoded)
          println("annotation size:" + eachTerm.annotations.size)
        }
      }
    }
  }

scala reflection miss inherit class java annotation

2 Answers