Chapter 11 Caching Mechanism

Shiro provides a Cache abstraction similar to Spring , that is, Shiro itself does not implement Cache , but abstracts Cache again, which is convenient to replace different underlying Cache implementations. For some concepts of Cache , please refer to my " Spring Cache Abstraction Detailed": http://jinnianshilongnian.iteye.com/blog/2001040 .

 

Cache interface provided by Shiro : 

Java code  

1. public  interface  Cache<K, V> {  
2.     / / Get the value in the cache according to the Key  
3.     public V get(K key) throws CacheException;  
4.     //Put the key-value into the cache and return the previous value in the cache  
5.     public V put(K key, V value) throws CacheException;   
6.     //Remove the value corresponding to the key in the cache and return the value  
7.     public V remove(K key) throws CacheException;  
8.     // clear the entire cache  
9.     public void clear() throws CacheException;  
10.     //return cache size  
11.     public int size();  
12.     //Get all the keys in the cache  
13.     public Set<K> keys();  
14.     //Get all the values ​​in the cache  
15.     public Collection<V> values();  
16. }  

  

The CacheManager interface provided by Shiro : 

Java code  

1. public  interface  CacheManager {  
2.     //Get a Cache based on the cache name  
3.     public <K, V> Cache<K, V> getCache(String name) throws CacheException;  
4. }  

  

Shiro also provides CacheManagerAware for injecting CacheManager : 

Java code  

1. public  interface  CacheManagerAware {  
2.     //Inject CacheManager  
3.     void  setCacheManager(CacheManager cacheManager);  
4. }  

 

The corresponding component ( DefaultSecurityManager ) in Shiro will automatically detect whether the corresponding object (such as Realm ) implements CacheManagerAware and automatically inject the corresponding CacheManager .

  

The use cases in this chapter use the same code from Chapter 6.

 

Realm cache

Shiro provides CachingRealm, which implements the CacheManagerAware interface and provides some basic implementations of caching; in addition, AuthenticatingRealm and AuthorizingRealm provide caching of AuthenticationInfo and AuthorizationInfo information respectively.

 

ini placement   

Java code  

1. userRealm=com.github.zhangkaitao.shiro.chapter11.realm.UserRealm  
2. userRealm.credentialsMatcher=$credentialsMatcher  
3. userRealm.cachingEnabled=true  
4. userRealm.authenticationCachingEnabled=true  
5. userRealm.authenticationCacheName=authenticationCache  
6. userRealm.authorizationCachingEnabled=true  
7. userRealm.authorizationCacheName=authorizationCache  
8. securityManager.realms=$userRealm  
9.   
10. cacheManager=org.apache.shiro.cache.ehcache.EhCacheManager  
11. cacheManager.cacheManagerConfigFile=classpath:shiro-ehcache.xml  
12. securityManager.cacheManager=$cacheManager   

userRealm.cachingEnabled: enable caching, default false;

userRealm.authenticationCachingEnabled : Enable authentication caching, that is, cache AuthenticationInfo information, the default is false ;

userRealm.authenticationCacheName : the cache name for caching AuthenticationInfo information;

userRealm. authorizationCachingEnabled : Enable authorization caching, that is, cache AuthorizationInfo information, default false ;

userRealm. authorizationCacheName : the cache name for caching AuthorizationInfo information;

cacheManager：缓存管理器，此处使用EhCacheManager，即Ehcache实现，需要导入相应的Ehcache依赖，请参考pom.xml；

 

因为测试用例的关系，需要将Ehcache的CacheManager改为使用VM单例模式：

this.manager = new net.sf.ehcache.CacheManager(getCacheManagerConfigFileInputStream());

改为

this.manager = net.sf.ehcache.CacheManager.create(getCacheManagerConfigFileInputStream());

 

测试用例 

Java代码  

1. @Test  
2. public void testClearCachedAuthenticationInfo() {  
3.     login(u1.getUsername(), password);  
4.     userService.changePassword(u1.getId(), password + "1");  
5.   
6.     RealmSecurityManager securityManager =  
7.      (RealmSecurityManager) SecurityUtils.getSecurityManager();  
8.     UserRealm userRealm = (UserRealm) securityManager.getRealms().iterator().next();  
9.     userRealm.clearCachedAuthenticationInfo(subject().getPrincipals());  
10.   
11.     login(u1.getUsername(), password + "1");  
12. }   

首先登录成功（此时会缓存相应的AuthenticationInfo），然后修改密码；此时密码就变了；接着需要调用Realm的clearCachedAuthenticationInfo方法清空之前缓存的AuthenticationInfo；否则下次登录时还会获取到修改密码之前的那个AuthenticationInfo；

 

Java代码  

1. @Test  
2. public void testClearCachedAuthorizationInfo() {  
3.     login(u1.getUsername(), password);  
4.     subject().checkRole(r1.getRole());  
5.     userService.correlationRoles(u1.getId(), r2.getId());  
6.   
7.     RealmSecurityManager securityManager =  
8.       (RealmSecurityManager) SecurityUtils.getSecurityManager();  
9.     UserRealm userRealm = (UserRealm)securityManager.getRealms().iterator().next();  
10.     userRealm.clearCachedAuthorizationInfo(subject().getPrincipals());  
11.   
12.     subject().checkRole(r2.getRole());  
13. }   

和之前的用例差不多；此处调用Realm的clearCachedAuthorizationInfo清空之前缓存的AuthorizationInfo；

 

另外还有clearCache，其同时调用clearCachedAuthenticationInfo和clearCachedAuthorizationInfo，清空AuthenticationInfo和AuthorizationInfo。

 

UserRealm还提供了clearAllCachedAuthorizationInfo、clearAllCachedAuthenticationInfo、clearAllCache，用于清空整个缓存。

 

在某些清空下这种方式可能不是最好的选择，可以考虑直接废弃Shiro的缓存，然后自己通过如AOP机制实现自己的缓存；可以参考：

https://github.com/zhangkaitao/es/tree/master/web/src/main/java/com/sishuok/es/extra/aop

 

另外如果和Spring集成时可以考虑直接使用Spring的Cache抽象，可以考虑使用SpringCacheManagerWrapper，其对Spring Cache进行了包装，转换为Shiro的CacheManager实现：

https://github.com/zhangkaitao/es/blob/master/web/src/main/java/org/apache/shiro/cache/spring/SpringCacheManagerWrapper.java 

 

Session缓存

当我们设置了SecurityManager的CacheManager时，如：

Java代码  

1. securityManager.cacheManager=$cacheManager  

 

当我们设置SessionManager时：

Java代码  

1. sessionManager=org.apache.shiro.session.mgt.DefaultSessionManager  
2. securityManager.sessionManager=$sessionManager   

如securityManager实现了SessionsSecurityManager，其会自动判断SessionManager是否实现了CacheManagerAware接口，如果实现了会把CacheManager设置给它。然后sessionManager会判断相应的sessionDAO（如继承自CachingSessionDAO）是否实现了CacheManagerAware，如果实现了会把CacheManager设置给它；如第九章的MySessionDAO就是带缓存的SessionDAO；其会先查缓存，如果找不到才查数据库。

 

对于CachingSessionDAO，可以通过如下配置设置缓存的名称：

Java代码  

1. sessionDAO=com.github.zhangkaitao.shiro.chapter11.session.dao.MySessionDAO  
2. sessionDAO.activeSessionsCacheName=shiro-activeSessionCache   

activeSessionsCacheName is shiro-activeSessionCache by default .