图解jdk1.8新特性（3）--- 注解与类型推测优化

public class AnnotationTest {
    
    @Target(ElementType.TYPE)
    @Retention(RetentionPolicy.RUNTIME)
    public @interface Filters {
        Filter[] value();
    }
    
    @Target(ElementType.TYPE)
    @Retention(RetentionPolicy.RUNTIME)
    @Repeatable(Filters.class)
    public @interface Filter {
        String value();
    }
    
    @Filter("filter1")
    @Filter("filter2")
    public interface Filterable {
        
    }
    
    @Filters({@Filter("filter1"), @Filter("filter2")})
    public interface Filterable2 {
        
    }
    
    public static void main(String[] args) {
        for (Filter filter : Filterable.class.getAnnotationsByType(Filter.class)) {
            System.out.println(filter.value());
        }
        for (Filters filter : Filterable.class.getAnnotationsByType(Filters.class)) {
            System.out.println(filter.value().length);
        }
        for (Filter filter : Filterable2.class.getAnnotationsByType(Filter.class)) {
            System.out.println(filter.value());
        }
        for (Filters filter : Filterable2.class.getAnnotationsByType(Filters.class)){
            System.out.println(filter.value().length);
        }
    }
}

输出如下：
filter1
filter2
2
filter1
filter2
2

value.getOrDefault("asas", Value.<String>defaultValue());