zapp有一篇精彩的评论，回答了所有这些问题:

new Reflections("my.package").getTypesAnnotatedWith(MyAnnotation.class)

You can find classes with any given annotation with ClassGraph, as well as searching for other criteria of interest, e.g. classes that implement a given interface. (Disclaimer, I am the author of ClassGraph.) ClassGraph can build an abstract representation of the entire class graph (all classes, annotations, methods, method parameters, and fields) in memory, for all classes on the classpath, or for classes in whitelisted packages, and you can query that class graph however you want. ClassGraph supports more classpath specification mechanisms and classloaders than any other scanner, and also works seamlessly with the new JPMS module system, so if you base your code on ClassGraph, your code will be maximally portable. See the API here.

zapp有一篇精彩的评论，回答了所有这些问题:

new Reflections("my.package").getTypesAnnotatedWith(MyAnnotation.class)

Classloader API没有“枚举”方法，因为类加载是一个“按需”活动——在类路径中通常有数千个类，其中只有一小部分是需要的(目前仅rt.jar就有48MB !)

因此，即使您可以枚举所有的类，这也会非常耗费时间和内存。

简单的方法是在设置文件(xml或任何适合你的文件)中列出相关的类;如果您希望自动执行此操作，请将自己限制在一个JAR或一个类目录中。

使用org.springframework.context.annotation.ClassPathScanningCandidateComponentProvider

API

从基本包扫描类路径的组件提供程序。然后，它对结果类应用排除和包括过滤器来查找候选类。

ClassPathScanningCandidateComponentProvider scanner =
new ClassPathScanningCandidateComponentProvider(<DO_YOU_WANT_TO_USE_DEFALT_FILTER>);

scanner.addIncludeFilter(new AnnotationTypeFilter(<TYPE_YOUR_ANNOTATION_HERE>.class));

for (BeanDefinition bd : scanner.findCandidateComponents(<TYPE_YOUR_BASE_PACKAGE_HERE>))
    System.out.println(bd.getBeanClassName());

在Spring中，您还可以使用AnnotationUtils类编写以下代码。例如:

Class<?> clazz = AnnotationUtils.findAnnotationDeclaringClass(Target.class, null);

要了解更多细节和所有不同的方法，请查看官方文档: https://docs.spring.io/spring/docs/current/javadoc-api/org/springframework/core/annotation/AnnotationUtils.html