Shiro AnnotationHandler注解处理器设计概念

顶端抽象类AnnotationHandler

该类是关乎注解的处理类，只涉及到注解的一些行为，符合面向对象的原则

承上启下抽象类AuthorizingAnnotationHandler

该类是权限注解处理器类，涉及到注解的行为所以继承了AnnotationHandler，又因为涉及到权限判断所以定义了判断权限的抽象方法，抽象化判断方法，使用子类具体实现判断方法

具体实现类RoleAnnotationHandler

提供权限注解的信息和权限判断的方法实现

public RoleAnnotationHandler() {
        super(RequiresRoles.class);
    }

具体实现

public void assertAuthorized(Annotation a) throws AuthorizationException {
    if (!(a instanceof RequiresRoles)) return;

    RequiresRoles rrAnnotation = (RequiresRoles) a;
    String[] roles = rrAnnotation.value();

    if (roles.length == 1) {
        getSubject().checkRole(roles[0]);
        return;
    }
    if (Logical.AND.equals(rrAnnotation.logical())) {
        getSubject().checkRoles(Arrays.asList(roles));
        return;
    }
    if (Logical.OR.equals(rrAnnotation.logical())) {
        // Avoid processing exceptions unnecessarily - "delay" throwing the exception by calling hasRole first
        boolean hasAtLeastOneRole = false;
        for (String role : roles) if (getSubject().hasRole(role)) hasAtLeastOneRole = true;
        // Cause the exception if none of the role match, note that the exception message will be a bit misleading
        if (!hasAtLeastOneRole) getSubject().checkRole(roles[0]);
    }
}