Java 中注解可以添加在方法的参数上

Run.java

public class Run {
    @Target(ElementType.PARAMETER)
    @Retention(RetentionPolicy.RUNTIME)
    static @interface QueryParam {
        String value();
    }

    public void testAnnotation(@QueryParam("action") String action) {
        System.out.printf("action is %s\n", action);
    }

    public static void exec() throws NoSuchMethodException {
        Class<?> cls = Run.class;
        Method method = cls.getMethod("testAnnotation", String.class);
        Annotation[][] annotations = method.getParameterAnnotations();
        for (int i = 0; i < annotations.length; i++) {
                Annotation[] annotations1 = annotations[i];
                for (Annotation annotation: annotations1) {
                    if (annotation instanceof QueryParam) {
                        QueryParam param = (QueryParam) annotation;
                        System.out.printf("annotation simple name is %s and value is %s\n",
                                param.annotationType().getSimpleName(),
                                param.value());
                        String action = param.value() + "=======";
                        try {
                            method.invoke(new Run(), action);
                        } catch (IllegalAccessException | InvocationTargetException e) {
                            e.printStackTrace();
                        }
                    }

                }
        }
    }
}