在Spring中有一个类CachingUserDetailsService实现了UserDetailsService接口，该类使用静态代理模式为UserDetailsService提供缓存功能。该类源码如下：
CachingUserDetailsService.java
public class CachingUserDetailsService implements UserDetailsService { private UserCache userCache = new NullUserCache(); private final UserDetailsService delegate; CachingUserDetailsService(UserDetailsService delegate) { this.delegate = delegate; } public UserCache getUserCache() { return this.userCache; } public void setUserCache(UserCache userCache) { this.userCache = userCache; } public UserDetails loadUserByUsername(String username) { UserDetails user = this.userCache.getUserFromCache(username); if (user == null) { user = this.delegate.loadUserByUsername(username); } Assert.notNull(user, "UserDetailsService " + this.delegate + " returned null for username " + username + ". This is an interface contract violation"); this.userCache.putUserInCache(user); return user; }} CachingUserDetailsService默认的userCache属性值为new NullUserCache()，该对象并未实现缓存。因为我打算使用EhCache来缓存UserDetails，所以需要使用Spring的EhCacheBasedUserCache类，该类是UserCache接口的实现类，主要是缓存操作。
缓存UserDetails到Ehcache的具体实现如下：
ehcache.xml
<?xml version="1.0" encoding="UTF-8"?><ehcache xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:noNamespaceSchemaLocation="http://ehcache.org/ehcache.xsd"> <!-- 磁盘缓存位置 --> <diskStore path="java.io.tmpdir" /> <cache name="userCache" maxElementsInMemory="0" eternal="true" overflowToDisk="true" diskPersistent="true" memoryStoreEvictionPolicy="LRU"> </cache></ehcache>
UserDetailsCacheConfig.java
@Slf4j@Configurationpublic class UserDetailsCacheConfig { @Autowired private CustomUserDetailsService customUserDetailsService; @Bean public UserCache userCache(){ try { EhCacheBasedUserCache userCache = new EhCacheBasedUserCache(); val cacheManager = CacheManager.getInstance(); val cache = cacheManager.getCache("userCache"); userCache.setCache(cache); return userCache; } catch (Exception e) { e.printStackTrace(); log.error(e.getMessage()); } return null; } @Bean public UserDetailsService userDetailsService(){ Constructor<CachingUserDetailsService> ctor = null; try { ctor = CachingUserDetailsService.class.getDeclaredConstructor(UserDetailsService.class); } catch (NoSuchMethodException e) { e.printStackTrace(); } Assert.notNull(ctor, "CachingUserDetailsService constructor is null"); ctor.setAccessible(true); CachingUserDetailsService cachingUserDetailsService = BeanUtils.instantiateClass(ctor, customUserDetailsService); cachingUserDetailsService.setUserCache(userCache()); return cachingUserDetailsService; }} 使用
@Autowiredprivate UserDetailsService userDetailsService;
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