java8 开始支持，对某个字段或者类上面的多个Anno，会自动转换成Annos
example@PropertySource("a")
@PropertySource("b")
class A {}
等价于
@PropertySources(["a"])
class A {}
支持重复注解的annotation
必须说明自己支持重复注解并且指明重复注解类
@Target(ElementType.TYPE)
@Retention(RetentionPolicy.RUNTIME)
@documented
@Repeatable(PropertySources.class)
public @interface PropertySource {
String name() default "";
String[] value();
boolean ignoreResourceNotFound() default false;
String encoding() default "";
Class factory() default PropertySourceFactory.class;
}
@Target(ElementType.TYPE)
@Retention(RetentionPolicy.RUNTIME)
@documented
public @interface PropertySources {
PropertySource[] value();
}
