SpringShiro每次请求的权限校验，都会调用一次doGetAuthorizationInfo的问题

Posted 2022-01-26 逐知逐行

        公司项目里用到SpringShiro权限校验，采用Redis做为SecurityManager的缓存管理。在doGetAuthorizationInfo方法打了断点，发现每次的请求，都会调用一次doGetAuthorizationInfo方法获取当前用户的权限数据。

         查看源码AuthorizingRealm的getAuthorizationInfo方法如下：

protected AuthorizationInfo getAuthorizationInfo(PrincipalCollection principals) 
    if (principals == null) 
        return null;
    
    AuthorizationInfo info = null;
    if (log.isTraceEnabled()) 
        log.trace("Retrieving AuthorizationInfo for principals [" + principals + "]");
    
    Cache<Object, AuthorizationInfo> cache = getAvailableAuthorizationCache();
    if (cache != null) 
        if (log.isTraceEnabled()) 
            log.trace("Attempting to retrieve the AuthorizationInfo from cache.");
        
        Object key = getAuthorizationCacheKey(principals);
        info = cache.get(key);
        if (log.isTraceEnabled()) 
            if (info == null) 
                log.trace("No AuthorizationInfo found in cache for principals [" + principals + "]");
             else 
                log.trace("AuthorizationInfo found in cache for principals [" + principals + "]");
            
        
    

    if (info == null) 
        // Call template method if the info was not found in a cache
        info = doGetAuthorizationInfo(principals);
        // If the info is not null and the cache has been created, then cache the authorization info.
        if (info != null && cache != null) 
            if (log.isTraceEnabled()) 
                log.trace("Caching authorization info for principals: [" + principals + "].");
            
            Object key = getAuthorizationCacheKey(principals);
            cache.put(key, info);
        
    
    return info;

发现：

Object key = getAuthorizationCacheKey(principals);

获取的key是principals的toString方法返回值，而SecurityUtils.getSubject().getPrincipal()方法每次返回的都是新的对象，所以key每次都是动态变化的。所以只要在AuthorizingRealm的实现类中复写getAuthorizationCacheKey方法，将其返回当前的sessionId即可： 

protected Object getAuthorizationCacheKey(PrincipalCollection principals) 
    return WebUtil.REQUEST.get().getSession().getId();

WebUtil.REQUEST.get()，是获取当前的HttpServletRequest的，项目里封装的方法。

        复写getAuthorizationCacheKey方法后，在getAuthorizationInfo方法中，同一个session就可以获取已经缓存起来的权限，不需要每次请求都调用一次doGetAuthorizationInfo方法了。不知道是不是还有其他更好的解决方案。