我正在使用jdk.compiler模块和启用了预览功能的Java15编写一个java编译器插件。根据oracle的说法，java9中引入的jdk.compiler模块包含了java8的tools.jar中的所有api，除了com.sun.tools.javac.tree包。我要做的是找到所有用注解注解的类，并获得value（）属性，在这里是class<？>类型。
插件代码：

public class ExtensionMethodPlugin implements Plugin{
  @Override
  public String getName() {
    return "ExtensionMethodPlugin";
  }

  @Override
  public void init(JavacTask task, String... args) {
    task.addTaskListener(new TaskListener() {
      @Override
      public void started(TaskEvent event) {

      }

      @Override
      public void finished(TaskEvent event) {
        if (event.getKind() != TaskEvent.Kind.PARSE) {
          return;
        }

        event.getCompilationUnit().accept(new TreeScanner<Void, Void>() {
          @Override
          public Void visitClass(ClassTree node, Void aVoid) {
            var trees = Trees.instance(task);
            var targetClass = InstrumentationUtils.findExtensionTargetForClass(node, trees, event.getCompilationUnit());
            if (targetClass.isEmpty()) {
              return super.visitClass(node, aVoid);
            }

            var methods = node
              .getMembers()
              .stream()
              .filter(e -> e instanceof MethodTree)
              .map(e -> (MethodTree) e)
              .filter(tree -> tree.getReturnType() != null)
              .filter(e -> InstrumentationUtils.shouldInstrumentMethod(e, targetClass.get()))
              .collect(Collectors.toList());

            throw new RuntimeException("Not implemented");
          }
        }, null);
      }
    });
  }
}

Jmeter 实用程序代码：

@UtilityClass
public class InstrumentationUtils {
  public Optional<Class<?>> findExtensionTargetForClass(ClassTree node, Trees trees, CompilationUnitTree tree) {
    return node
      .getModifiers()
      .getAnnotations()
      .stream()
      .filter(a -> Extension.class.getSimpleName().equals(a.getAnnotationType().toString()))
      .findFirst()
      .map(e -> InstrumentationUtils.findConstantTargetClassInAnnotationTree(e, trees, tree));
  }

  private Class<?> findConstantTargetClassInAnnotationTree(AnnotationTree tree, Trees trees, CompilationUnitTree compilationUnitTree) {
    return tree
      .getArguments()
      .stream()
      .filter(entry -> entry.getKind() == Tree.Kind.ASSIGNMENT)
      .findFirst()
      .map(e -> (AssignmentTree) e)
      .map(e -> classForName(e, trees, compilationUnitTree))
      .orElseThrow(() -> new RuntimeException("Cannot compile: Missing constant class target in annotation!"));
  }

  private Class<?> classForName(AssignmentTree tree, Trees trees, CompilationUnitTree compilationUnitTree){
    //Don't know how to move from here
  }
}

注解代码：

@Target({ElementType.TYPE})
@Retention(RetentionPolicy.SOURCE)
public @interface Extension {
  Class<?> value();
}

我发现的唯一解决方案涉及到使用jctree类，但正如我前面所说的，这些类不再可用。我知道我可以很容易地在jdk.compiler模块中强制导出该包，但我更愿意找到更好的方法。我试过用树形扫描仪，但结果一无所获：

tree.accept(new TreeScanner<Class<?>, Void>() {
      // b.class
      @Override
      public Class<?> visitAssignment(AssignmentTree node, Void unused) {
        return node.getExpression().accept(new TreeScanner<Class<?>, Void>(){
          //.class
          @Override
          public Class<?> visitMemberSelect(MemberSelectTree node, Void unused) {
            return node.getExpression().accept(new TreeScanner<Class<?>, Void>(){
              // class ???
              @Override
              public Class<?> visitIdentifier(IdentifierTree node, Void unused) {
                trees.printMessage(Diagnostic.Kind.WARNING, node.getName(),  tree, compilationUnitTree);
                return super.visitIdentifier(node, unused);
              }
            }, null);
          }
        }, null);
      }
    }, null);

提前谢谢！