处理不同的注释具有相同的处理器实例

问题描述

我们已经在我们的项目中两个注解，我想基于类的两份名单，收集类中的注解，并创建一个合并输出。

We have two annotations in our project and I'd like to collect the annotated classes and create a merged output based on both lists of classes.

这是可能的只有一个处理器实例？我怎么知道，如果处理器实例与每一个注解类叫什么名字？

Is this possible with only one Processor instance? How do I know if the Processor instance was called with every annotated class?

推荐答案

框架调用 Processor.process 方法只一次（每个轮），并可以访问两个列表在通过传递 RoundEnvironment 参数同一时间。所以，你可以在同一个工艺处理两份名单方法调用。

The framework calls the Processor.process method only once (per round) and you can access both lists at the same time through the passed RoundEnvironment parameter. So you can process both lists in the same process method call.

要做到这个列表中的 SupportedAnnotationTypes 注释都标注：

To do this list both annotations in the SupportedAnnotationTypes annotation:

@SupportedAnnotationTypes({
    "hu.palacsint.annotation.MyAnnotation",
    "hu.palacsint.annotation.MyOtherAnnotation"
})
@SupportedSourceVersion(SourceVersion.RELEASE_6)
public class Processor extends AbstractProcessor { ... }

下面是一个样本过程方法：

@Override
public boolean process(final Set<? extends TypeElement> annotations,
        final RoundEnvironment roundEnv) {
    System.out.println("   > ---- process method starts " + hashCode());
    System.out.println("   > annotations: " + annotations);

    for (final TypeElement annotation: annotations) {
        System.out.println("   >  annotation: " + annotation.toString());
        final Set<? extends Element> annotateds =
            roundEnv.getElementsAnnotatedWith(annotation);
        for (final Element element: annotateds) {
            System.out.println("      > class: " + element);
        }
    }
    System.out.println("   > processingOver: " + roundEnv.processingOver());
    System.out.println("   > ---- process method ends " + hashCode());
    return false;
}

和它的输出：

   > ---- process method starts 21314930
   > annotations: [hu.palacsint.annotation.MyOtherAnnotation, hu.palacsint.annotation.MyAnnotation]
   >  annotation: hu.palacsint.annotation.MyOtherAnnotation
      > class: hu.palacsint.annotation.p2.OtherClassOne
   >  annotation: hu.palacsint.annotation.MyAnnotation
      > class: hu.palacsint.annotation.p2.ClassTwo
      > class: hu.palacsint.annotation.p3.ClassThree
      > class: hu.palacsint.annotation.p1.ClassOne
   > processingOver: false
   > ---- process method ends 21314930
   > ---- process method starts 21314930
   > roots: []
   > annotations: []
   > processingOver: true
   > ---- process method ends 21314930

它打印这些注释的所有类 MyAnnotation 或 MyOtherAnnotation 注释。

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